Long-life wide-width double-layer steel truss girder bridge temperature gradient fatigue load spectrum and construction method

Abstract

The invention discloses a temperature gradient fatigue load spectrum of a long-service-life wide-width double-layer steel truss girder bridge and a construction method. The temperature gradient fatigue load spectrum is composed of an upper-layer bridge floor vertical temperature gradient fatigue load spectrum, a lower-layer bridge floor vertical temperature gradient fatigue load spectrum, a transverse temperature gradient fatigue load spectrum and a main truss vertical temperature gradient fatigue load spectrum. According to the method, temperature gradient fatigue load spectrums of the long-service-life wide-width double-layer steel truss bridge suitable for designed service lives of 100 years, 150 years and 200 years are respectively constructed by using long-term monitoring data of temperature fields of upper and lower bridge surfaces and main trusses of the wide-width double-layer steel truss bridge and adopting a mean value clustering method. The constructed temperature gradient fatigue load spectrum fully reflects the temperature fatigue load characteristics of the wide-width double-layer truss girder bridge in different seasons, and the temperature fatigue stress process of the wide-width double-layer truss girder bridge can be used for simulating and calculating the typical fatigue detail temperature fatigue damage of the double-layer truss girder bridge.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge engineering, and in particular relates to a temperature gradient fatigue load spectrum and a construction method of a long-life wide double-deck steel truss bridge. Background Art

[0002] A double-deck truss bridge consists of a main truss, an upper deck system, and a lower deck system. Its complex structural system leads to a large difference in the temperature field between the main truss and the upper and lower deck systems. The various structures of the wide double-deck steel truss will produce longitudinal temperature fatigue stress under the action of the vertical nonlinear temperature gradient. Double-deck steel trusses have overall and local frame effects, which will produce transverse fatigue stress under the action of the transverse temperature gradient. Previous studies have shown that the coupled cyclic action of temperature load and vehicle load will significantly increase the fatigue cumulative damage of the details of the steel truss bridge, and the fatigue damage under the action of temperature and vehicle alone cannot be simply superimposed. The temperature action of the wide double-deck truss bridge includes the cyclic action of daily temperature difference and seasonal temperature difference. It is possible to construct a temperature gradient fatigue load spectrum suitable for wide double-deck steel trusses with a design service life of 200 years, and conduct fatigue damage analysis of wide double-deck steel trusses. Summary of the invention

[0003] The technology to be solved by the present invention is to provide a temperature gradient fatigue load spectrum and a construction method for a long-life wide double-deck steel truss bridge.

[0004] The technical solution adopted to solve the above technical problems is:

[0005] A temperature gradient fatigue load spectrum for a long-life wide double-deck steel truss bridge, the model includes a vertical temperature gradient fatigue load spectrum for the upper deck, a vertical temperature gradient fatigue load spectrum for the lower deck, a transverse temperature gradient fatigue load spectrum, and a vertical temperature gradient fatigue load spectrum for the main truss;

[0006] The vertical temperature gradient fatigue load spectrum of the upper deck is composed of five vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically:

[0007]

[0008] Where, T TGi (y) is the temperature of the vertical temperature sub-gradient of the i-th upper deck at position y, h T is the height of the upper bridge deck, TGi is the vertical temperature sub-gradient of the i-th upper bridge deck, T TGi,1 、T TGi,2 、T TGi,3 They are the top of the upper deck in the vertical temperature sub-gradient of the i-th upper deck, the top of the upper deck 0.7h away from the bottom of the upper deck T The temperature representative value at the height position and the bottom of the upper bridge deck, T TG1,1is the representative value of the temperature at the top of the upper deck in the first upper deck vertical temperature sub-gradient, ranging from [12.6, 13.5], in °C, T TG1,2 The vertical temperature sub-gradient of the first upper deck is 0.7h away from the bottom of the upper deck. T The temperature at the position is representative, ranging from [5.8, 6.6], T TG1,3 is the representative value of the temperature at the bottom of the upper deck in the first upper deck vertical temperature sub-gradient, ranging from [0.9, 1.7], in °C, T TGi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the i-th upper deck, N d is the design service life, T TG1,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first upper deck, P(T TG1 (y))、P(T TG2 (y))、P(T TG3 (y))、P(T TG4 (y))、P(T TG5 (y)) are the occurrence probabilities of the five upper deck vertical temperature sub-gradients within the design service life, T TG1,1 、T TG2,1 、T TG3,1 、T TG4,1 、T TG5,1 are the representative values ​​of the temperature at the top of the upper bridge deck in the five upper bridge deck vertical temperature sub-gradients;

[0009] The vertical temperature gradient fatigue load spectrum of the lower deck is composed of five vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically:

[0010]

[0011] Where, T BGi (y) is the temperature of the vertical temperature sub-gradient of the ith lower deck at position y, h B is the height of the lower deck, BGi is the vertical temperature sub-gradient of the ith lower deck, T BGi,1 、T BGi,2 、T BGi,3 、T BGi,4 They are the top of the lower deck and the lower deck section 0.9h in the vertical temperature sub-gradient of the i-th lower deck. B At, lower deck section 0.8h B The representative temperature value of the bottom of the lower bridge deck is T BG1,1 is the representative value of the temperature of the top plate of the lower deck in the first lower deck vertical temperature sub-gradient, ranging from [10.2, 11.3], in °C, T BG1,2The vertical temperature sub-gradient of the first lower deck is 0.9h in the lower deck section. B The temperature at is the representative value, the value range is [6.6,7.6], the unit is ℃, T BG1,3 The vertical temperature sub-gradient of the first lower deck in the lower deck section at 0.8h B The temperature at is the representative value, the value range is [3.6,4.8], the unit is ℃, T BG1,4 is the representative value of the temperature at the bottom of the lower deck in the first lower deck vertical temperature sub-gradient, ranging from [0.8, 2.2], in °C, T BGi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the ith lower deck, T BG1,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first lower deck, P(T BG1 (y))、P(T BG2 (y))、P(T BG3 (y))、P(T BG4 (y))、P(T BG5 (y)) are the occurrence probabilities of the five lower deck vertical temperature sub-gradients within the design service life, T BG1,1 、T BG2,1 、T BG3,1 、T BG4,1 、T BG5,1 are the representative values ​​of the temperature at the top of the lower deck in the five vertical temperature sub-gradients of the lower deck;

[0012] The transverse temperature gradient fatigue load spectrum is composed of five transverse temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically:

[0013]

[0014] Where, T THi (x) is the temperature of the ith transverse temperature sub-gradient at position x, L is the width of the upper bridge deck, THi is the ith transverse temperature sub-gradient, T THi,1 、T THi,2 、T THi,3 、T THi,4 、T THi,5 are the temperature representative values ​​of the upper deck top plate at the edge of the sunny side, the upper deck top plate at a distance of L / 4 from the sunny side edge, the upper deck top plate at a distance of L / 2 from the sunny side edge, the upper deck top plate at a distance of 3L / 4 from the sunny side edge, and the upper deck top plate at a distance of the shady side edge in the i-th transverse temperature sub-gradient, T TH1,1 is the temperature representative value at the edge of the upper deck top plate in the first transverse temperature sub-gradient, ranging from [1.6, 3.2], in °C, T TH1,2is the representative temperature value of the upper bridge deck top plate at a distance of L / 4 from the edge of the sun side in the first transverse temperature sub-gradient, with a range of [1.9, 2.9], in °C, T TH1,3 is the representative temperature value of the upper bridge deck top plate at a distance of L / 2 from the edge of the sun side in the first transverse temperature sub-gradient, with a range of [2.8,3.9], in °C, T TH1,4 is the representative temperature value of the upper bridge deck top plate at a distance of 3L / 4 from the edge of the sun side in the first transverse temperature sub-gradient, with a range of [3.0,4.2], in °C, T TH1,5 is the representative temperature value of the upper bridge deck top plate at the distance from the edge of the shaded surface in the first transverse temperature sub-gradient, T THq,w is the temperature representative value at the wth typical height in the ith lateral temperature sub-gradient, T TH1,w is the representative temperature value at the jth typical height in the first transverse temperature sub-gradient, P(T TH1 (x))、P(T TH2 (x))、P(T TH3 (x))、P(T TH4 (x))、P(T TH5 (x)) are the occurrence probabilities of the five transverse temperature sub-gradients within the design service life, T TH1,1 、T TH2,1 、T TH3,1 、T TH4,1 、T TH5,1 They are the representative values ​​of the temperature at the top plate of the upper bridge deck at the distance from the edge of the sunny side in the five transverse temperature sub-gradients;

[0015] The temperature gradient fatigue load spectrum of the main truss includes the vertical temperature gradient fatigue load spectrum of the upper chord, the vertical temperature gradient fatigue load spectrum of the lower chord and the vertical temperature gradient fatigue load spectrum of the web.

[0016] The vertical temperature gradient fatigue load spectrum of the upper chord is composed of four vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically:

[0017]

[0018] Where, T TXi (y) is the temperature of the vertical temperature sub-gradient of the i-th upper chord at position y, H T is the height of the upper chord, TXi is the vertical temperature sub-gradient of the i-th upper chord, T TXi,1 、T TXi,2 are the representative values ​​of the temperature at the top plate of the upper chord and the bottom plate of the upper chord in the vertical temperature sub-gradient of the i-th upper chord, T TX1,1is the representative value of the temperature at the top plate of the upper chord in the first upper chord vertical temperature sub-gradient, ranging from [8.8, 10.2], in °C, T TX1,2 is the representative value of the temperature at the bottom plate of the upper chord in the first upper chord vertical temperature sub-gradient, ranging from [12.3, 13.6], in °C, T TXi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the i-th upper chord, T TX1,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first upper chord, P(T TX1 (y))、P(T TX2 (y))、P(T TX3 (y))、P(T TX4 (y)) are the occurrence probabilities of the vertical temperature sub-gradients of the four upper chords within the design service life, T TX1,1 、T TX2,1 、T TX3,1 、T TX4,1 are the representative values ​​of the temperature at the top plate of the upper chord in the four upper chord vertical temperature sub-gradients;

[0019] The vertical temperature gradient fatigue load spectrum of the lower chord is composed of four vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically:

[0020]

[0021] Where, T BXi (y) is the temperature of the vertical temperature sub-gradient of the ith lower chord at position y, H B is the height of the lower chord, BXi is the vertical temperature sub-gradient of the ith lower chord, T BXi,1 、T BXi,2 are the representative values ​​of the temperature at the top plate of the lower chord and the bottom plate of the lower chord in the vertical temperature sub-gradient of the i-th lower chord, T BX1,1 is the representative value of the temperature at the top plate of the lower chord in the vertical temperature sub-gradient of the first lower chord, T BX1,2 is the representative value of the temperature at the bottom plate of the lower chord in the first lower chord vertical temperature sub-gradient, ranging from [6.6, 8.3], in °C, T BXi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the i-th lower chord, ranging from [9.8, 11.2], in °C, T BX1,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first lower chord, P(T BX1 (y))、P(T BX2 (y))、P(T BX3 (y))、P(T BX4(y)) are the occurrence probabilities of the vertical temperature sub-gradients of the four lower chords within the design service life, T BX1,1 、T BX2,1 、T BX3,1 、T BX4,1 are the representative values ​​of the temperature at the top plate of the lower chord in the four vertical temperature sub-gradients of the lower chord;

[0022] The web vertical temperature gradient fatigue load spectrum is composed of four vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically:

[0023]

[0024] Where, T Wi (y) is the temperature of the vertical temperature sub-gradient of the i-th web member at position y, H w is the height of the web, Wi is the vertical temperature sub-gradient of the ith web, T Wi,1 、T Wi,2 are the representative values ​​of the temperature at the outer wing plate of the web bar and the inner wing plate of the web bar in the vertical temperature sub-gradient of the i-th web bar, T W1,1 is the representative value of the temperature at the outer wing plate of the web in the first web vertical temperature sub-gradient, with a value range of [6.3,7.6], in °C, T W1,2 is the representative value of the temperature at the inner wing plate of the web in the first web vertical temperature sub-gradient, with a value range of [4.6,5.8], in °C, T Wi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the i-th web member, T W1,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first web member, P(T W1 (y))、P(T W2 (y))、P(T W3 (y))、P(T W4 (y)) are the occurrence probabilities of the four web member vertical temperature sub-gradients within the design service life, T W1,1 、T W2,1 、T W3,1 、T W4,1 are the representative values ​​of the temperature at the wing plate outside the web in the four vertical temperature sub-gradients of the web;

[0025] The method for constructing the temperature fatigue load spectrum of a long-life wide double-deck steel truss bridge includes the following steps:

[0026] Step 1. Arrange temperature measuring points on a wide double-deck steel truss bridge, collect temperature values ​​of the measuring points at certain intervals, and obtain a measured temperature gradient time history curve;

[0027] Step 2. According to the temperature stress σ(z,t) obtained from the measured temperature gradient time history curve, the temperature stress amplitude data set [Δ(z)] is obtained;

[0028] [Δ(z)]=[(Δσ1(z),m1(z))L(Δσ i (z),m i (z))L(Δσ I (z),m I (z))]

[0029] In the formula, Δσ i (z) is the temperature stress amplitude of type i at the measuring point z, m i (z) is the number of loadings corresponding to the i-th type of temperature stress amplitude at the measuring point z, and I is the total number of types of temperature stress amplitudes;

[0030] Step 3. Fit the temperature stress amplitude data set [Δ(z)] with a probability density function to obtain a temperature stress amplitude probability density curve. Use the Latin hypercube sampling method to sample the temperature stress amplitude probability density curve to obtain a temperature stress amplitude sample. Extend the obtained temperature stress amplitude sample to the corresponding design service life to obtain the temperature stress amplitude and stress cycle number corresponding to the design service life at different locations, and form a new temperature stress amplitude data set [Δ Nfs (z)];

[0031]

[0032] Where N fs is the total number of temperature stress cycle loading, is the i-th type temperature stress amplitude corresponding to the design service life at the measuring point z, is the number of cycles of the i-th type of temperature stress corresponding to the design service life at the measuring point z;

[0033] Step 4. New temperature stress amplitude dataset obtained from step 3 The equivalent fatigue temperature data set of wide double-deck steel truss bridge at different positions corresponding to the design service life is determined according to the following formula [T Π (z)]:

[0034]

[0035] Step 5. Analyze the equivalent fatigue temperature data set of wide double-deck steel truss bridge [T Π (z)], determine the optimal cluster number k of the temperature fatigue load spectrum of the wide double-deck steel truss bridge, and use the K-means cluster analysis method to analyze the equivalent fatigue temperature data set [T Π(z)] are clustered to determine the k temperature sub-gradients applicable to the wide double-deck steel truss bridge with the corresponding design service life, as well as the occurrence probability of each temperature sub-gradient, so as to obtain the temperature gradient fatigue load spectrum of the long-life wide double-deck steel truss bridge.

[0036] Preferably, in step 1, the interval time for collecting the temperature of the measuring points is 60 to 1200 seconds.

[0037] Preferably, the temperature stress σ(z, t) in step 2 is obtained according to the following formula:

[0038]

[0039] Where γ is the structural system coefficient, γ = 1 + ρ, ρ is the temperature secondary bending moment influence coefficient, A is the cross section of the wide double-deck steel truss bridge, I is the moment of inertia of the cross section of the wide double-deck steel truss bridge, M is the upper deck height, lower deck height, chord height, top plate width or web member height of the wide double-deck steel truss bridge, b(z) is the chord section of the wide double-deck steel truss bridge, the width of the deck section or the height of the double-deck steel truss, z s It is the distance from the neutral axis of the chord section or bridge deck section to the bottom of the corresponding section of a wide double-deck steel truss bridge, or the lateral distance from the neutral axis of the section of a wide double-deck steel truss bridge to the specified origin of the section.

[0040] Preferably, the method for arranging temperature measuring points on the wide double-layer steel truss bridge in step 1 is: arranging a measuring point on the bottom plate of the upper deck of the wide double-layer steel truss bridge as the coordinate origin, and taking the measuring point as the coordinate origin, arranging measuring points on the web and the top plate along the vertical height direction, arranging a total of 8 measuring points, and the positions of the measuring points are expressed as 0.00m, h and 0.1m from the vertical distance from the lower surface of the bottom plate of the upper deck of the wide double-layer steel truss bridge. T -1.10m,h T -0.60m,h T -0.30m,h T -0.20m,h T -0.10m,h T -0.05m,h T ,This temperature measurement point method is used to construct the vertical temperature gradient fatigue load spectrum of the upper bridge deck.

[0041] Preferably, the method for arranging temperature measuring points on the wide double-layer steel truss bridge in step 1 is: arranging a measuring point on the bottom plate of the lower deck of the wide double-layer steel truss bridge as the coordinate origin, and taking the measuring point as the coordinate origin, arranging measuring points on the web and the top plate along the vertical height direction, arranging a total of 6 measuring points, and the positions of the measuring points are expressed as 0.00m, h and 0.1m from the vertical distance from the lower surface of the bottom plate of the lower deck of the wide double-layer steel truss bridge. B -0.85m,h B -0.45m,hB -0.20m,h B -0.05m,h B The arrangement method of temperature measuring points is used to construct the vertical temperature gradient fatigue load spectrum of the lower bridge deck.

[0042] Preferably, the method for arranging temperature measuring points on the wide double-deck steel truss bridge in step 1 is: arranging a measuring point on the edge of the positive side of the top plate of the upper bridge deck of the wide double-deck steel truss bridge, and taking the measuring point as the coordinate origin, arranging measuring points on the top plate along the width direction of the top plate, arranging a total of 7 measuring points, and the positions of the measuring points are expressed as horizontal distances from the edge of the positive side of the top plate as 0.00m, L-30.05m, L-26.65m, L-15.85m, L-5.05m, L-1.20m, and L. The method for arranging temperature measuring points is used to construct a transverse temperature gradient fatigue load spectrum of the upper bridge deck.

[0043] Preferably, the method for arranging temperature measuring points on the wide double-layer steel truss bridge in step 1 is: arranging one measuring point at the top plate of the upper chord and the bottom plate of the upper chord of the wide double-layer steel truss bridge, and the position of the measuring point is expressed by the distance from the bottom plate of the upper chord of the wide double-layer steel truss as 0.00m, H T The temperature measurement point method is used to construct the vertical temperature fatigue load spectrum of the upper chord. A measurement point is arranged at the top plate of the lower chord and the bottom plate of the lower chord of the wide double-layer steel truss bridge. The measurement point position is expressed by the distance from the bottom plate of the lower chord of the wide double-layer steel truss beam as 0.00m, H B The temperature measurement point method is used to construct the vertical temperature fatigue load spectrum of the lower chord. A measurement point is arranged on the outer side and inner side wing of the wide double-deck steel truss bridge, and the temperature measurement point method is used to construct the vertical temperature fatigue load spectrum of the web.

[0044] The beneficial effects of the present invention are as follows:

[0045] 1. The temperature gradient fatigue load spectrum of the long-life wide double-deck steel truss bridge proposed in the present invention can be used to construct the temperature stress history of the main truss and the upper and lower deck systems of the double-deck truss bridge, and calculate the fatigue damage at the details, which is of great significance to perfecting the anti-fatigue design system of the wide double-deck steel truss bridge.

[0046] 2. The method for constructing the temperature gradient fatigue load spectrum of a long-life wide double-deck steel truss bridge proposed in the present invention adopts a mean clustering algorithm, which can utilize the long-term monitoring data of the temperature field of the double-deck truss bridge to construct a temperature gradient fatigue load spectrum suitable for a design service life of 100, 150 and 200 years.

[0047] 3. The present invention measures the temperature gradient time-history curve and the temperature stress history, combines the probability density function fitting and the Latin hypercube sampling method, and can more accurately simulate and predict the temperature stress state of a wide double-deck steel truss bridge under different design service lives, providing a scientific basis for the long-term performance evaluation and maintenance of the bridge.

[0048] 4. The present invention clusters the measured data through the K-means cluster analysis method to determine the temperature sub-gradient and its occurrence probability, thereby constructing a more accurate temperature gradient fatigue load spectrum, which helps to improve the accuracy and reliability of bridge design and evaluation.

[0049] 5. The present invention provides data support for the maintenance, repair and reinforcement of wide double-deck steel truss bridges, which helps to extend the service life of the bridges, reduce the cost of the entire life cycle, and has significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a schematic diagram of the three-dimensional structure of a wide double-deck steel truss bridge.

[0051] Figure 2 It is the vertical temperature sub-gradient pattern of the upper deck of a wide double-layer steel truss girder.

[0052] Figure 3 is the probability of the gradient of the vertical temperature fatigue load spectrum of the upper deck of a wide double-layer steel truss girder.

[0053] Figure 4 This is a flow chart of Example 1 of the present invention.

[0054] Figure 5 This is the layout diagram of the vertical and transverse temperature measurement points for a wide double-deck steel truss bridge.

[0055] Figure 6 This is the temperature history curve at a typical measuring point of a wide double-deck steel truss bridge.

[0056] Figure 7 This is the vertical temperature sub-gradient pattern of the lower deck of a wide double-deck steel truss bridge.

[0057] Figure 8 is the probability of the gradient of the vertical temperature fatigue load spectrum of the lower deck of a wide double-deck steel truss girder.

[0058] Fig. 9 This is the transverse temperature sub-gradient pattern of the upper deck of a wide double-deck steel truss bridge.

[0059] Fig.10 Probability of gradient of transverse temperature fatigue load spectrum for upper deck of wide double-layer steel truss girder.

[0060] Fig.11 It is the vertical temperature sub-gradient model of the main truss of a wide double-layer steel truss girder.

[0061] Fig.12 is the probability of the vertical temperature fatigue spectrum gradient of the upper chord of a wide double-layer steel truss girder.

[0062] Fig.13 is the probability of the vertical temperature fatigue spectrum gradient of the lower chord of a wide double-layer steel truss girder.

[0063] Fig.14 The probability of the gradient of the thermal fatigue load spectrum of the web member of a wide double-layer steel truss girder. DETAILED DESCRIPTION

[0064] The present invention will be further described in detail below in conjunction with the accompanying drawings and examples, but the present invention is not limited to the following embodiments.

[0065] Example 1

[0066] Taking a wide double-deck steel truss bridge in the north as an example, the three-dimensional structure is shown in the figure below: Figure 1 The temperature fatigue load spectrum of the long-life wide double-deck steel truss bridge of this embodiment includes the vertical temperature gradient fatigue load spectrum of the upper bridge deck, the vertical temperature gradient fatigue load spectrum of the lower bridge deck, the transverse temperature gradient fatigue load spectrum of the upper bridge deck, and the vertical temperature gradient fatigue load spectrum of the main truss.

[0067] The vertical temperature gradient fatigue load spectrum of the upper deck is composed of five vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically:

[0068]

[0069] Where, T TGi (y) is the temperature of the vertical temperature sub-gradient of the i-th upper deck at position y, h T is the height of the upper bridge deck, TGi is the vertical temperature sub-gradient of the i-th upper bridge deck, T TGi,1 、T TGi,2 、T TGi,3 They are the top of the upper deck in the vertical temperature sub-gradient of the i-th upper deck, the top of the upper deck 0.7h away from the bottom of the upper deck T The temperature representative value at the height position and the bottom of the upper bridge deck, T TG1,1 is the representative value of the temperature at the top of the upper deck in the first upper deck vertical temperature sub-gradient, ranging from [12.6, 13.5], in °C, T TG1,2 The vertical temperature sub-gradient of the first upper deck is 0.7h away from the bottom of the upper deck. T The temperature at the position is representative, ranging from [5.8, 6.6], T TG1,3 is the representative value of the temperature at the bottom of the upper deck in the first upper deck vertical temperature sub-gradient, ranging from [0.9, 1.7], in °C, TTGi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the i-th upper deck, N d is the design service life, T TG1,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first upper deck, P(T TG1 (y))、P(T TG2 (y))、P(T TG3 (y))、P(T TG4 (y))、P(T TG5 (y)) are the occurrence probabilities of the five upper deck vertical temperature sub-gradients within the design service life, T TG1,1 、T TG2,1 、T TG3,1 、T TG4,1 、T TG5,1 are the representative values ​​of the temperature at the top of the upper bridge deck in the five upper bridge deck vertical temperature sub-gradients. In this embodiment, T TG1,1 The value is 13.3℃, ​​T TG1,2 The value is 6.4℃, T TG1,3 The value is 1.3℃;

[0070] According to the vertical temperature gradient fatigue load spectrum of the upper deck of the wide double-deck steel truss bridge, the representative temperature values ​​of each sub-gradient at different heights corresponding to the design service life of 100 years, 150 years and 200 years are shown in Table 1. The vertical temperature sub-gradient mode is as follows: Figure 2 As shown, the sub-gradient T TG1 ~T TG5 The probability of occurrence is 30.3%, 13.2%, 2.6%, 28.9%, 25%, see Figure 3 .

[0071] Table 1 Representative values ​​of vertical temperature fatigue load spectrum gradient temperature of upper deck of wide double-layer steel truss girder

[0072]

[0073] exist Figure 4 In the present embodiment, the method for constructing the vertical temperature gradient fatigue load spectrum of the upper deck of a wide double-deck steel truss bridge comprises the following steps:

[0074] Step 1. Arrange a measuring point on the upper deck bottom plate of the wide double-deck steel truss bridge as the coordinate origin, and arrange measuring points on the web and top plate along the vertical height direction with this measuring point as the coordinate origin. Arrange 8 measuring points in total, such as Figure 5The measuring point positions are expressed as 0.00m, 0.50m, 1.10m, 1.30m, 1.40m, 1.50m, 1.55m, 1.60m in vertical distance from the lower surface of the upper deck bottom plate of the wide double-layer steel truss girder. The temperature value of each measuring point is collected once every 600 seconds, once every 1 second, or once every 1800 seconds.

[0075] Step 2. Based on the temperature stress σ(z,t) obtained from the measured temperature gradient time history curve, the temperature stress history at different positions of the wide double-deck steel truss bridge is constructed. The temperature history curve is as follows: Figure 6 As shown, the rain flow counting method is used to obtain the number of times different stress amplitudes act in the temperature stress history, and the stress amplitudes are counted and summarized to obtain the temperature stress amplitude data set [Δ(z)];

[0076] [Δ(z)]=[(Δσ1(z),m1(z))L(Δσ i (z),m i (z))L(Δσ I (z),m I (z))]

[0077] In the formula, Δσ i (z) is the temperature stress amplitude of type i at the measuring point z, m i (z) is the number of loadings corresponding to the i-th type of temperature stress amplitude at the measuring point z, and I is the total number of types of temperature stress amplitudes;

[0078] Among them, the temperature stress σ(z,t) is obtained according to the following formula:

[0079]

[0080] Where, γ is the structural system coefficient, γ = 1 + ρ, ρ is the temperature secondary bending moment influence coefficient, A is the cross-sectional area of ​​the wide double-deck steel truss bridge, I is the moment of inertia of the cross-sectional area of ​​the wide double-deck steel truss bridge; M is the upper deck height, lower deck height, chord height, top plate width or web section height of the wide double-deck steel truss bridge, b(z) is the chord section width of the wide double-deck steel truss bridge or the upper deck section width or the lower deck section width or the truss height of the wide double-deck steel truss bridge, z s It is the distance from the neutral axis of the chord section or deck section to the bottom of the corresponding section of a wide double-layer steel truss bridge, or the transverse distance from the neutral axis of the section of a wide double-layer steel truss bridge to the specified origin of the section;

[0081] Step 3. Fit the temperature stress amplitude data set [Δ(z)] with a probability density function to obtain a temperature stress amplitude probability density curve. Use the Latin hypercube sampling method to sample the temperature stress amplitude probability density curve to obtain a temperature stress amplitude sample. Extend the obtained temperature stress amplitude sample to the corresponding design service life to obtain the temperature stress amplitude and stress cycle number corresponding to the design service life at different locations, and form a new temperature stress amplitude data set [Δ Nfs (z)];

[0082]

[0083] Where N fs is the total number of temperature stress cycle loading, is the i-th type temperature stress amplitude corresponding to the design service life at the measuring point z, is the number of cycles of the i-th type of temperature stress corresponding to the design service life at the measuring point z;

[0084] Step 4. New temperature stress amplitude dataset obtained from step 3 The equivalent fatigue temperature data set of wide double-deck steel truss bridge at different positions corresponding to the design service life is determined according to the following formula [T Π (z)]:

[0085]

[0086] Step 5. Analyze the equivalent fatigue temperature data set of wide double-deck steel truss bridge [T Π (z)], determine the optimal cluster number k of the temperature fatigue load spectrum of the wide double-deck steel truss bridge, and use the K-means cluster analysis method to analyze the equivalent fatigue temperature data set [T Π (z)] are clustered to determine the k temperature sub-gradients that are suitable for wide double-deck steel truss bridges with corresponding design service life; as well as the occurrence probability of each temperature sub-gradient, so as to obtain the temperature gradient fatigue load spectrum of long-life wide double-deck steel truss bridge.

[0087] The vertical temperature gradient fatigue load spectrum of the lower deck is composed of five vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically:

[0088]

[0089] Where, T BGi (y) is the temperature of the vertical temperature sub-gradient of the ith lower deck at position y, h B is the height of the lower deck, BGi is the vertical temperature sub-gradient of the ith lower deck, T BGi,1 、T BGi,2 、T BGi,3 、TBGi,4 They are the top of the lower deck and the lower deck section 0.9h in the vertical temperature sub-gradient of the i-th lower deck. B At, lower deck section 0.8h B The representative temperature value of the bottom of the lower bridge deck is T BG1,1 is the representative value of the temperature of the top plate of the lower deck in the first lower deck vertical temperature sub-gradient, ranging from [10.2, 11.3], in °C, T BG1,2 The vertical temperature sub-gradient of the first lower deck is 0.9h in the lower deck section. B The temperature at is the representative value, the value range is [6.6,7.6], the unit is ℃, T BG1,3 The vertical temperature sub-gradient of the first lower deck in the lower deck section at 0.8h B The temperature at is the representative value, the value range is [3.6,4.8], the unit is ℃, T BG1,4 is the representative value of the temperature at the bottom of the lower deck in the first lower deck vertical temperature sub-gradient, ranging from [0.8, 2.2], in °C, T BGi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the ith lower deck, T BG1,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first lower deck, P(T BG1 (y))、P(T BG2 (y))、P(T BG3 (y))、P(T BG4 (y))、P(T BG5 (y)) are the occurrence probabilities of the five lower deck vertical temperature sub-gradients within the design service life, T BG1,1 、T BG2,1 、T BG3,1 、T BG4,1 、T BG5,1 are the representative values ​​of the temperature at the top of the lower deck in the five lower deck vertical temperature sub-gradients. BG1,1 The value is 10.7℃, T BG1,2 The value is 6.8℃, T BG1,3 The value is 3.8℃, T BG1,4 The value is 1.6℃.

[0090] According to the vertical temperature gradient fatigue load spectrum of the lower deck of the wide double-deck steel truss bridge, the representative temperature values ​​of each sub-gradient at different heights corresponding to the design service life of 100 years, 150 years and 200 years are shown in Table 2. The vertical temperature sub-gradient mode is as follows: Figure 7 Sub-gradient T BG1 ~T BG5The probability of occurrence is 38.2%, 3.9%, 7.9%, 17.1%, 32.9%, see Figure 8 .

[0091] Table 2 Representative values ​​of vertical temperature fatigue load spectrum gradient temperature of the lower deck of wide double-layer steel truss beams

[0092]

[0093]

[0094] A method for constructing a vertical temperature gradient fatigue load spectrum model for the lower deck of a wide double-deck steel truss bridge includes the following steps:

[0095] Step 1: Arrange temperature measuring points on the top plate, bottom plate and web plate of the lower deck of the wide double-layer steel truss girder and collect the temperature. Arrange 6 measuring points in total, such as Figure 5 As shown, the measuring point positions are represented by vertical distances from the lower surface of the bottom plate of the lower deck of the wide double-layer steel truss girder as 0.00m, 0.05m, 0.20m, 0.45m, 0.85m, and 1.60m. The temperature value of each measuring point is collected once every 600 seconds, once every 1 second, or once every 1800 seconds to obtain the measured temperature gradient time history curve;

[0096] Steps 2 to 5 are the same as the method for constructing the vertical temperature fatigue load spectrum of the upper bridge deck.

[0097] The transverse temperature gradient fatigue load spectrum consists of five transverse temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically:

[0098]

[0099] Where, T THi (x) is the temperature of the ith transverse temperature sub-gradient at position x, L is the width of the upper bridge deck, THi is the ith transverse temperature sub-gradient, T THi,1 、T THi,2 、T THi,3 、T THi,4 、T THi,5 are the temperature representative values ​​of the upper deck top plate at the edge of the sunny side, the upper deck top plate at a distance of L / 4 from the sunny side edge, the upper deck top plate at a distance of L / 2 from the sunny side edge, the upper deck top plate at a distance of 3L / 4 from the sunny side edge, and the upper deck top plate at a distance of the shady side edge in the i-th transverse temperature sub-gradient, T TH1,1 is the temperature representative value at the edge of the upper deck top plate in the first transverse temperature sub-gradient, ranging from [1.6, 3.2], in °C, T TH1,2is the representative temperature value of the upper bridge deck top plate at a distance of L / 4 from the edge of the sun side in the first transverse temperature sub-gradient, with a range of [1.9, 2.9], in °C, T TH1,3 is the representative temperature value of the upper bridge deck top plate at a distance of L / 2 from the edge of the sun side in the first transverse temperature sub-gradient, with a range of [2.8,3.9], in °C, T TH1,4 is the representative temperature value of the upper bridge deck top plate at a distance of 3L / 4 from the edge of the sun side in the first transverse temperature sub-gradient, with a range of [3.0,4.2], in °C, T TH1,5 is the representative temperature value of the upper bridge deck top plate at the distance from the edge of the shaded surface in the first transverse temperature sub-gradient, T THq,w is the temperature representative value at the wth typical height in the ith lateral temperature sub-gradient, T TH1,w is the representative temperature value at the jth typical height in the first transverse temperature sub-gradient, P(T TH1 (x))、P(T TH2 (x))、P(T TH3 (x))、P(T TH4 (x))、P(T TH5 (x)) are the occurrence probabilities of the five transverse temperature sub-gradients within the design service life, T TH1,1 、T TH2,1 、T TH3,1 、T TH4,1 、T TH5,1 are the representative values ​​of the temperature at the top of the upper bridge deck away from the edge of the sunny side in the five transverse temperature sub-gradients. In this example, T TH1,1 The value is 2.8℃, T TH1,2 The value is 2.2℃, T TH1,3 The value is 3.2℃, T TH1,4 The value is 3.0℃, T TH1,5 The value is 2.0℃.

[0100] According to the above-mentioned transverse temperature gradient fatigue load spectrum of the wide double-deck steel truss bridge, the representative temperature values ​​of each sub-gradient at different heights corresponding to the design service life of 100 years, 150 years, and 200 years are shown in Table 3. The transverse temperature sub-gradient mode is as follows: Fig. 9 Sub-gradient T TH1 ~T TH5 The probability of occurrence is 43.8%, 31.3%, 3.1%, 12.5%, 9.4%, see Fig.10 .

[0101] Table 3 Representative values ​​of gradient temperature of transverse fatigue load spectrum of double-layer steel truss beams

[0102]

[0103] The method for constructing the transverse temperature gradient fatigue load spectrum of a wide double-deck steel truss bridge includes the following steps:

[0104] Step 1, arrange a measuring point on the edge of the positive side of the top plate of the upper deck of the wide double-deck steel truss bridge, and take the measuring point as the coordinate origin, arrange measuring points on the top plate along the width direction of the top plate, and arrange 7 measuring points in total. The positions of the measuring points are expressed as 0.00m, 0.05m, 0.20m, 0.45m, 0.85m, and 1.60m in horizontal distance from the edge of the positive side of the top plate. The temperature value of each measuring point is collected once every 600 seconds, once every 1 second, or once every 1800 seconds to obtain a measured temperature gradient time history curve;

[0105] Steps 2 to 5 are the same as the method for constructing the vertical temperature fatigue load spectrum model of the upper bridge deck.

[0106] The temperature gradient fatigue load spectrum of the main truss includes the vertical temperature gradient fatigue load spectrum of the upper chord, the vertical temperature gradient fatigue load spectrum of the lower chord, and the vertical temperature gradient fatigue load spectrum of the web.

[0107] The vertical temperature gradient fatigue load spectrum of the upper chord is composed of four vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically:

[0108]

[0109] Where, T TXi (y) is the temperature of the vertical temperature sub-gradient of the i-th upper chord at position y, H T is the height of the upper chord, TXi is the vertical temperature sub-gradient of the i-th upper chord, T TXi,1 、T TXi,2 are the representative values ​​of the temperature at the top plate of the upper chord and the bottom plate of the upper chord in the vertical temperature sub-gradient of the i-th upper chord, T TX1,1 is the representative value of the temperature at the top plate of the upper chord in the first upper chord vertical temperature sub-gradient, ranging from [8.8, 10.2], in °C, T TX1,2 is the representative value of the temperature at the bottom plate of the upper chord in the first upper chord vertical temperature sub-gradient, ranging from [12.3, 13.6], in °C, T TXi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the i-th upper chord, T TX1,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first upper chord, P(T TX1 (y))、P(T TX2 (y))、P(T TX3 (y))、P(T TX4(y)) are the occurrence probabilities of the vertical temperature sub-gradients of the four upper chords within the design service life, T TX1,1 、T TX2,1 、T TX3,1 、T TX4,1 They are the representative values ​​of the temperature at the top plate of the upper chord in the four upper chord vertical temperature sub-gradients.

[0110] Among them, T TX1,1 The value is 9.3℃, T TX1,2 The value is 12.7℃. According to the vertical temperature gradient fatigue load spectrum of the upper chord of the wide double-deck steel truss bridge, the temperature representative values ​​of each sub-gradient at different heights corresponding to the design service life of 100 years, 150 years, and 200 years are shown in Table 4. The vertical temperature sub-gradient mode is as follows: Fig.11 Sub-gradient T TX1 ~T TX4 The probability of occurrence is 9.2%, 35.5%, 48.7%, 6.6%, see Fig.12 .

[0111] Table 4 Representative values ​​of vertical temperature fatigue load spectrum gradient temperature of upper chord of wide double-layer steel truss girder

[0112]

[0113] The vertical temperature gradient fatigue load spectrum of the lower chord is composed of four vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically:

[0114]

[0115] Where, T BXi (y) is the temperature of the vertical temperature sub-gradient of the ith lower chord at position y, H B is the height of the lower chord, BXi is the vertical temperature sub-gradient of the ith lower chord, T BXi,1 、T BXi,2 are the representative values ​​of the temperature at the top plate of the lower chord and the bottom plate of the lower chord in the vertical temperature sub-gradient of the i-th lower chord, T BX1,1 is the representative value of the temperature at the top plate of the lower chord in the vertical temperature sub-gradient of the first lower chord, T BX1,2 is the representative value of the temperature at the bottom plate of the lower chord in the first lower chord vertical temperature sub-gradient, ranging from [6.6, 8.3], in °C, T BXi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the i-th lower chord, ranging from [9.8, 11.2], in °C, T BX1,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first lower chord, P(T BX1(y))、P(T BX2 (y))、P(T BX3 (y))、P(T BX4 (y)) are the occurrence probabilities of the vertical temperature sub-gradients of the four lower chords within the design service life, T BX1,1 、T BX2,1 、T BX3,1 、T BX4,1 are the representative values ​​of the temperature at the top plate of the lower chord in the four lower chord vertical temperature sub-gradients. BX1,1 The value is 7.7℃, T BX1,2 The value is 10.1℃.

[0116] According to the vertical temperature gradient fatigue load spectrum of the lower chord of the wide double-deck steel truss bridge, the representative temperature values ​​of each sub-gradient at different heights corresponding to the design service life of 100 years, 150 years, and 200 years are shown in Table 5. The vertical temperature sub-gradient mode is as follows: Fig.11 Sub-gradient T BX1 ~T BX4 The probability of occurrence is 6.6%, 39.5%, 21.1%, 32.9%, see Fig.13 .

[0117] Table 5 Representative values ​​of vertical temperature fatigue load spectrum gradient temperature of the lower chord of wide double-layer steel truss beam

[0118]

[0119] The web vertical temperature gradient fatigue load spectrum is composed of four vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically:

[0120]

[0121] Where, T Wi (y) is the temperature of the vertical temperature sub-gradient of the i-th web member at position y, H w is the height of the web, Wi is the vertical temperature sub-gradient of the ith web, T Wi,1 、T Wi,2 are the representative values ​​of the temperature at the outer wing plate of the web bar and the inner wing plate of the web bar in the vertical temperature sub-gradient of the i-th web bar, T W1,1 is the representative value of the temperature at the outer wing plate of the web in the first web vertical temperature sub-gradient, with a value range of [6.3,7.6], in °C, T W1,2 is the representative value of the temperature at the inner wing plate of the web in the first web vertical temperature sub-gradient, with a value range of [4.6,5.8], in °C, T Wi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the i-th web member, T W1,jis the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first web member, P(T W1 (y))、P(T W2 (y))、P(T W3 (y))、P(T W4 (y)) are the occurrence probabilities of the four web member vertical temperature sub-gradients within the design service life, T W1,1 、T W2,1 、T W3,1 、T W4,1 They are the representative values ​​of the temperature at the wing plate outside the web member in the four vertical temperature sub-gradients of the web member.

[0122] Among them, T W1,1 The value is 7.4℃, T W1,1 The value is 4.9℃. According to the vertical temperature fatigue load spectrum of the web member of the wide double-deck steel truss bridge, the representative temperature values ​​of each sub-gradient at different heights corresponding to the design service life of 100 years, 150 years, and 200 years are shown in Table 6. The vertical temperature gradient mode is as follows Fig.11 Sub-gradient T W1 ~T W4 The probability of occurrence is 30.4%, 15.2%, 23.9%, 30.4%, see Fig.14 .

[0123] Table 6 Representative values ​​of gradient temperature of vertical temperature fatigue load spectrum of wide double-layer steel truss web members

[0124]

[0125] The method for constructing a temperature gradient fatigue load spectrum model for a wide double-deck steel truss bridge main truss comprises the following steps:

[0126] Step 1: arrange a measuring point at the upper chord top plate, the upper chord bottom plate, the lower chord top plate, the lower chord bottom plate, and the inner and outer wing plates of the web member of the wide double-deck steel truss bridge, respectively, and collect the temperature value of each measuring point once every 600 seconds, once every 1 second, or once every 1800 seconds to obtain a measured temperature gradient time history curve;

[0127] Steps 2 to 5 are the same as the method for constructing the vertical temperature fatigue load spectrum model of the upper bridge deck.

Claims

1. A temperature gradient fatigue load spectrum for a long-life wide double-deck steel truss bridge, characterized by: The model includes the vertical temperature gradient fatigue load spectrum of the upper bridge deck, the vertical temperature gradient fatigue load spectrum of the lower bridge deck, the transverse temperature gradient fatigue load spectrum, and the vertical temperature gradient fatigue load spectrum of the main truss; The vertical temperature gradient fatigue load spectrum of the upper deck is composed of five vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically: Where, T TGi (y) is the temperature of the vertical temperature sub-gradient of the i-th upper deck at position y, h T is the height of the upper bridge deck, TGi is the vertical temperature sub-gradient of the i-th upper bridge deck, T TGi,1 、T TGi,2 、T TGi,3 They are the top of the upper deck in the vertical temperature sub-gradient of the i-th upper deck, the top of the upper deck 0.7h away from the bottom of the upper deck T The temperature representative value at the height position and the bottom of the upper bridge deck, T TG1,1 is the representative value of the temperature at the top of the upper deck in the first upper deck vertical temperature sub-gradient, ranging from [12.6, 13.5], in °C, T TG1,2 The vertical temperature sub-gradient of the first upper deck is 0.7h away from the bottom of the upper deck. T The temperature at the position is representative, ranging from [5.8, 6.6], T TG1,3 is the representative value of the temperature at the bottom of the upper deck in the first upper deck vertical temperature sub-gradient, ranging from [0.9, 1.7], in °C, T TGi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the i-th upper deck, N d is the design service life, T TG1,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first upper deck, P(T TG1 (y))、P(T TG2 (y))、P(T TG3 (y))、P(T TG4 (y))、P(T TG5 (y)) are the occurrence probabilities of the five upper deck vertical temperature sub-gradients within the design service life, T TG1,1 、T TG2,1 、T TG3,1 、T TG4,1 、T TG5,1 are the representative values ​​of the temperature at the top of the upper bridge deck in the five upper bridge deck vertical temperature sub-gradients; The vertical temperature gradient fatigue load spectrum of the lower deck is composed of five vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically: Where, T BGi (y) is the temperature of the vertical temperature sub-gradient of the ith lower deck at position y, h B is the height of the lower deck, BGi is the vertical temperature sub-gradient of the ith lower deck, T BGi,1 , T BGi,2 , T BGi,3 , T BGi,4 They are the top of the lower deck and the lower deck section 0.9h in the vertical temperature sub-gradient of the i-th lower deck. B At, lower deck section 0.8h B The representative temperature value of the bottom of the lower bridge deck is T BG1,1 is the representative value of the temperature of the top plate of the lower deck in the first lower deck vertical temperature sub-gradient, ranging from [10.2, 11.3], in °C, T BG1,2 The vertical temperature sub-gradient of the first lower deck is 0.9h in the lower deck section. B The temperature at is the representative value, the value range is [6.6,7.6], the unit is ℃, T BG1,3 The vertical temperature sub-gradient of the first lower deck in the lower deck section at 0.8h B The temperature at is the representative value, the value range is [3.6,4.8], the unit is ℃, T BG1,4 is the representative value of the temperature at the bottom of the lower deck in the first lower deck vertical temperature sub-gradient, ranging from [0.8, 2.2], in °C, T BGi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the ith lower deck, T BG1,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first lower deck, P(T BG1 (y))、P(T BG2 (y))、P(T BG3 (y))、P(T BG4 (y))、P(T BG5 (y)) are the occurrence probabilities of the five lower deck vertical temperature sub-gradients within the design service life, T BG1,1 , T BG2,1 , T BG3,1 , T BG4,1 , T BG5,1 are the representative values ​​of the temperature at the top of the lower deck in the five vertical temperature sub-gradients of the lower deck; The transverse temperature gradient fatigue load spectrum is composed of five transverse temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically: Where, T THi (x) is the temperature of the ith transverse temperature sub-gradient at position x, L is the width of the upper bridge deck, THi is the ith transverse temperature sub-gradient, T THi,1 , T THi,2 , T THi,3 , T THi,4 , T THi,5 are the temperature representative values ​​of the upper deck top plate at the edge of the sunny side, the upper deck top plate at a distance of L / 4 from the sunny side edge, the upper deck top plate at a distance of L / 2 from the sunny side edge, the upper deck top plate at a distance of 3L / 4 from the sunny side edge, and the upper deck top plate at a distance of the shady side edge in the i-th transverse temperature sub-gradient, T TH1,1 is the temperature representative value at the edge of the upper deck top plate in the first transverse temperature sub-gradient, ranging from [1.6, 3.2], in °C, T TH1,2 is the representative temperature value of the upper bridge deck top plate at a distance of L / 4 from the edge of the sun side in the first transverse temperature sub-gradient, with a range of [1.9, 2.9], in °C, T TH1,3 is the representative temperature value of the upper bridge deck top plate at a distance of L / 2 from the edge of the sun side in the first transverse temperature sub-gradient, with a range of [2.8,3.9], in °C, T TH1,4 is the representative temperature value of the upper bridge deck top plate at a distance of 3L / 4 from the edge of the sun side in the first transverse temperature sub-gradient, with a range of [3.0,4.2], in °C, T TH1,5 is the representative temperature value of the upper bridge deck top plate at the distance from the edge of the shaded surface in the first transverse temperature sub-gradient, T THq,w is the temperature representative value at the wth typical height in the ith lateral temperature sub-gradient, T TH1,w is the representative temperature value at the jth typical height in the first transverse temperature sub-gradient, P(T TH1 (x))、P(T TH2 (x))、P(T TH3 (x))、P(T TH4 (x))、P(T TH5 (x)) are the occurrence probabilities of the five transverse temperature sub-gradients within the design service life, T TH1,1 , T TH2,1 , T TH3,1 , T TH4,1 , T TH5,1 They are the representative values ​​of the temperature at the top plate of the upper bridge deck at the distance from the edge of the sunny side in the five transverse temperature sub-gradients; The temperature gradient fatigue load spectrum of the main truss includes the vertical temperature gradient fatigue load spectrum of the upper chord, the vertical temperature gradient fatigue load spectrum of the lower chord and the vertical temperature gradient fatigue load spectrum of the web. The vertical temperature gradient fatigue load spectrum of the upper chord is composed of four vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically: Where, T TXi (y) is the temperature of the vertical temperature sub-gradient of the i-th upper chord at position y, H T is the height of the upper chord, TXi is the vertical temperature sub-gradient of the i-th upper chord, T TXi,1 , T TXi,2 are the representative values ​​of the temperature at the top plate of the upper chord and the bottom plate of the upper chord in the vertical temperature sub-gradient of the i-th upper chord, T TX1,1 is the representative value of the temperature at the top plate of the upper chord in the first upper chord vertical temperature sub-gradient, ranging from [8.8, 10.2], in °C, T TX1,2 is the representative value of the temperature at the bottom plate of the upper chord in the first upper chord vertical temperature sub-gradient, ranging from [12.3, 13.6], in °C, T TXi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the i-th upper chord, T TX1,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first upper chord, P(T TX1 (y))、P(T TX2 (y))、P(T TX3 (y))、P(T TX4 (y)) are the occurrence probabilities of the vertical temperature sub-gradients of the four upper chords within the design service life, T TX1,1 , T TX2,1 , T TX3,1 , T TX4,1 are the representative values ​​of the temperature at the top plate of the upper chord in the four upper chord vertical temperature sub-gradients; The vertical temperature gradient fatigue load spectrum of the lower chord is composed of four vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically: Where, T BXi (y) is the temperature of the vertical temperature sub-gradient of the ith lower chord at position y, H B is the height of the lower chord, BXi is the vertical temperature sub-gradient of the ith lower chord, T BXi,1 , T BXi,2 are the representative values ​​of the temperature at the top plate of the lower chord and the bottom plate of the lower chord in the vertical temperature sub-gradient of the i-th lower chord, T BX1,1 is the representative value of the temperature at the top plate of the lower chord in the vertical temperature sub-gradient of the first lower chord, T BX1,2 is the representative value of the temperature at the bottom plate of the lower chord in the first lower chord vertical temperature sub-gradient, ranging from [6.6, 8.3], in °C, T BXi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the i-th lower chord, ranging from [9.8, 11.2], in °C, T BX1,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first lower chord, P(T BX1 (y))、P(T BX2 (y))、P(T BX3 (y))、P(T BX4 (y)) are the occurrence probabilities of the vertical temperature sub-gradients of the four lower chords within the design service life, T BX1,1 , T BX2,1 , T BX3,1 , T BX4,1 are the representative values ​​of the temperature at the top plate of the lower chord in the four vertical temperature sub-gradients of the lower chord; The web vertical temperature gradient fatigue load spectrum is composed of four vertical temperature sub-gradients and the probability of occurrence of the sub-gradients within the design service life, specifically: Where, T Wi (y) is the temperature of the vertical temperature sub-gradient of the i-th web member at position y, H w is the height of the web, Wi is the vertical temperature sub-gradient of the ith web, T Wi,1 、T Wi,2 are the representative values ​​of the temperature at the outer wing plate of the web bar and the inner wing plate of the web bar in the vertical temperature sub-gradient of the i-th web bar, T W1,1 is the representative value of the temperature at the outer wing plate of the web in the first web vertical temperature sub-gradient, with a value range of [6.3,7.6], in °C, T W1,2 is the representative value of the temperature at the inner wing plate of the web in the first web vertical temperature sub-gradient, with a value range of [4.6,5.8], in °C, T Wi,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the i-th web member, T W1,j is the temperature representative value at the jth typical height in the vertical temperature sub-gradient of the first web member, P(T W1 (y))、P(T W2 (y))、P(T W3 (y))、P(T W4 (y)) are the occurrence probabilities of the four web member vertical temperature sub-gradients within the design service life, T W1,1 , T W2,1 , T W3,1 、T W4,1 They are the representative values ​​of the temperature at the wing plate outside the web member in the four vertical temperature sub-gradients of the web member.

2. The method for constructing the temperature fatigue load spectrum of the long-life wide double-deck steel truss bridge according to claim 1 is characterized by: The following steps are involved: Step 1. Arrange temperature measuring points on a wide double-deck steel truss bridge, collect temperature values ​​of the measuring points at certain intervals, and obtain a measured temperature gradient time history curve; Step 2. According to the temperature stress σ(z,t) obtained from the measured temperature gradient time history curve, the temperature stress amplitude data set [Δ(z)] is obtained; [Δ(z)]=[(Δσ1(z),m1(z))…(Δσ i (z),m i (z))…(Δσ I (z),m I (z))] In the formula, Δσ i (z) is the temperature stress amplitude of type i at the measuring point z, m i (z) is the number of loadings corresponding to the i-th type of temperature stress amplitude at the measuring point z, and I is the total number of types of temperature stress amplitudes; Step 3. Fit the temperature stress amplitude data set [Δ(z)] with a probability density function to obtain a temperature stress amplitude probability density curve. Use the Latin hypercube sampling method to sample the temperature stress amplitude probability density curve to obtain a temperature stress amplitude sample. Extend the obtained temperature stress amplitude sample to the corresponding design service life to obtain the temperature stress amplitude and stress cycle number corresponding to the design service life at different locations, and form a new temperature stress amplitude data set [Δ Nfs (z)]; Where N fs is the total number of temperature stress cycle loading, is the i-th type temperature stress amplitude corresponding to the design service life at the measuring point z, is the number of cycles of the i-th type of temperature stress corresponding to the design service life at the measuring point z; Step 4. New temperature stress amplitude dataset obtained from step 3 The equivalent fatigue temperature data set of wide double-deck steel truss bridge at different positions corresponding to the design service life is determined according to the following formula [T Π (z)]: Step 5. Analyze the equivalent fatigue temperature data set of wide double-deck steel truss bridge [T Π (z)], determine the optimal cluster number k of the temperature fatigue load spectrum of the wide double-deck steel truss bridge, and use the K-means cluster analysis method to analyze the equivalent fatigue temperature data set [T Π (z)] are clustered to determine the k temperature sub-gradients applicable to the wide double-deck steel truss bridge with the corresponding design service life, as well as the occurrence probability of each temperature sub-gradient, so as to obtain the temperature gradient fatigue load spectrum of the long-life wide double-deck steel truss bridge.

3. The method for constructing transverse and vertical temperature fatigue load spectra of a long-life wide double-deck steel truss bridge according to claim 2 is characterized in that: In step 1, the temperature of the measuring points is collected at intervals of 60 to 1200 seconds.

4. The method for constructing a temperature fatigue load spectrum of a long-life wide double-deck steel truss bridge according to claim 2 is characterized in that: The temperature stress σ(z, t) in step 2 is obtained according to the following formula: Where γ is the structural system coefficient, γ = 1 + ρ, ρ is the temperature secondary bending moment influence coefficient, A is the cross section of the wide double-deck steel truss bridge, I is the moment of inertia of the cross section of the wide double-deck steel truss bridge, M is the upper deck height, lower deck height, chord height, top plate width or web member height of the wide double-deck steel truss bridge, b(z) is the chord section of the wide double-deck steel truss bridge, the width of the deck section or the height of the double-deck steel truss, z s It is the distance from the neutral axis of the chord section or bridge deck section to the bottom of the corresponding section of a wide double-deck steel truss bridge, or the lateral distance from the neutral axis of the section of a wide double-deck steel truss bridge to the specified origin of the section.

5. The method for constructing a temperature fatigue load spectrum of a long-life wide double-deck steel truss bridge according to claim 2 is characterized in that: The method for arranging temperature measuring points on the wide double-layer steel truss bridge in step 1 is as follows: a measuring point is arranged on the bottom plate of the upper deck of the wide double-layer steel truss bridge as the coordinate origin, and the measuring point is used as the coordinate origin to arrange measuring points on the web and the top plate along the vertical height direction, and a total of m=8 measuring points are arranged, and the position of the measuring point is expressed as 0.00m, h T -1.10m,h T -0.60m,h T -0.30m,h T -0.20m,h T -0.10m,h T -0.05m,h T ,This temperature measurement point method is used to construct the vertical temperature gradient fatigue load spectrum of the upper bridge deck.

6. The method for constructing a temperature fatigue load spectrum of a long-life wide double-deck steel truss bridge according to claim 2 is characterized in that: The method for arranging temperature measuring points on the wide double-layer steel truss bridge in step 1 is as follows: a measuring point is arranged on the bottom plate of the lower deck of the wide double-layer steel truss bridge as the coordinate origin, and the measuring point is used as the coordinate origin to arrange measuring points on the web and the top plate along the vertical height direction, and a total of 6 measuring points are arranged, and the position of the measuring point is expressed as 0.00m, h B -0.85m,h B -0.45m,h B -0.20m,h B -0.05m,h B The arrangement method of temperature measuring points is used to construct the vertical temperature gradient fatigue load spectrum of the lower bridge deck.

7. The method for constructing transverse and vertical temperature fatigue load spectra of a long-life wide double-deck steel truss bridge according to claim 2 is characterized in that: The method for arranging temperature measuring points on the wide double-deck steel truss bridge in step 1 is as follows: a measuring point is arranged on the edge of the positive side of the top plate of the upper bridge deck of the wide double-deck steel truss bridge, and the measuring point is used as the coordinate origin to arrange measuring points on the top plate along the width direction of the top plate, with a total of 7 measuring points arranged, and the positions of the measuring points are expressed as 0.00m, L-30.05m, L-26.65m, L-15.85m, L-5.05m, L-1.20m, and L in terms of the horizontal distance from the edge of the positive side of the top plate. The method for arranging temperature measuring points is used to construct a transverse temperature gradient fatigue load spectrum of the upper bridge deck.

8. The method for constructing a temperature fatigue load spectrum of a long-life wide double-deck steel truss bridge according to claim 2 is characterized in that: The method for arranging temperature measuring points on the wide double-layer steel truss bridge in step 1 is as follows: a measuring point is arranged at the top plate of the upper chord of the wide double-layer steel truss bridge and at the bottom plate of the upper chord, and the position of the measuring point is represented by the distance from the bottom plate of the upper chord of the wide double-layer steel truss as 0.00m, H T The temperature measurement point method is used to construct the vertical temperature fatigue load spectrum of the upper chord. A measurement point is arranged at the top plate of the lower chord and the bottom plate of the lower chord of the wide double-layer steel truss bridge. The measurement point position is expressed by the distance from the bottom plate of the lower chord of the wide double-layer steel truss beam as 0.00m, H B The temperature measurement point method is used to construct the vertical temperature fatigue load spectrum of the lower chord. A measurement point is arranged on the outer side and inner side wing of the wide double-deck steel truss bridge, and the temperature measurement point method is used to construct the vertical temperature fatigue load spectrum of the web.

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