A bridge earthquake risk cost assessment method considering construction and operation periods

Abstract

The present invention belongs to the field of building construction technology, and specifically discloses a bridge earthquake risk cost assessment method that takes into account the construction and operation periods. The method comprehensively considers factors such as the bridge construction method, construction period, atmospheric environment of the bridge location, and earthquake zoning. A multi-stage earthquake risk probability distribution model for bridges is established, and the cost data in the bridge earthquake damage budget list and the repair time data caused by earthquake damage are imported into the bridge full-stage damage probability distribution formula. The time-varying curves of the direct and indirect costs of bridge earthquake disasters are obtained through conditional probability calculations. This can not only estimate the earthquake risk cost of the bridge throughout its life cycle, but also provide more accurate earthquake risk cost assessments for bridge construction investors, providing a reference for investment decisions.

Description

Technical Field

[0001] The present invention belongs to the technical field of building construction risk assessment, and in particular relates to a bridge earthquake risk cost assessment method taking into account the construction and operation periods. Background Art

[0002] Earthquake disasters, a major risk faced by bridges and roads, are difficult to predict and control. my country's bridge design codes stipulate seismic fortification requirements for bridge construction. For investors, assessing the post-earthquake risk costs associated with bridges designed with different seismic resistance levels is a crucial consideration in bridge construction decisions.

[0003] Currently, bridge earthquake risk cost assessments are limited to the post-earthquake repair budget during the operational phase after bridge construction is completed. With the increasing diversification of bridge types and the continuous expansion of their overall scale, the earthquake risk of bridges during the construction phase is becoming an increasingly important factor that cannot be ignored. Different construction methods and different construction plans all introduce uncertainty into the overall earthquake risk cost of bridges. Furthermore, during the normal operation of bridges, the aging of internal materials and components over time, as well as the loss of functionality, also impacts the earthquake risk cost. In summary, current bridge earthquake risk cost assessment methods rely on a single set of assessment factors, making it difficult to accurately assess the earthquake risk cost of bridges based on local conditions, bridge-specific requirements, and multiple factors and schemes. Therefore, this issue urgently needs to be addressed. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a bridge earthquake risk cost assessment method that takes into account the construction and operation periods. This method comprehensively considers factors such as the bridge construction method, construction period, the atmospheric environment of the bridge location, and earthquake zoning. It can not only estimate the earthquake risk cost of the bridge throughout its life cycle, but also provide bridge construction investors with a more accurate earthquake risk cost assessment, providing a reference for investment decisions.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A bridge earthquake risk cost assessment method considering construction and operation periods is characterized by including

[0007] S1: Determine the basic elements of the bridge construction plan; the basic elements include bridge type, construction method, bridge atmospheric environment, bridge site intensity zoning and bridge service life;

[0008] S2: Establish a multi-stage finite element model based on the bridge type and the corresponding construction method;

[0009] S3: The bridge environment includes a seismic environment and an atmospheric environment; an earthquake hazard curve is established based on the seismic environment of the bridge; and a steel bar degradation model inside the bridge is established based on the atmospheric environment of the bridge;

[0010] S4: After calculating the nonlinear time history response of all models using the cloud diagram method, the multi-stage finite element model is fitted with the seismic wave logarithm of the earthquake hazard curve to establish a probabilistic earthquake demand model;

[0011] S5: The steel bar degradation model is combined with the service life of the bridge according to the material degradation model to calculate the component capacity degradation model;

[0012] S6: The probabilistic seismic demand model is combined with the component capacity degradation model, and the seismic responses of the degraded components are calculated in sequence. The demand model is updated, and the fragility curve is plotted and convolved with the seismic risk curve to obtain a multi-stage seismic risk probability distribution model for the bridge.

[0013] S7: Draw a time-varying curve for the earthquake risk of a bridge over its entire life cycle; import the cost data and repair time data from the bridge earthquake damage budget list into the probability distribution formula for bridge damage at all stages, and obtain the time-varying curves for the direct and indirect costs of bridge earthquake disasters through conditional probability calculations;

[0014] S8: Evaluate the earthquake risk warning value of construction factors; preset the completion time of the bridge through the construction schedule, and use the completion time when the integral of the bridge's earthquake disaster cost time-varying curve to the construction phase accounts for 5% of the entire life cycle as the warning value. If the construction time is greater than the warning value, it indicates that the earthquake risk in the construction process needs to be taken seriously, and relevant earthquake-resistant measures should be taken to reduce losses.

[0015] Preferably, the multi-stage bridge model division includes the construction period and operation period of the bridge; the construction period divides the bridge construction process into multiple stages according to the construction plan, and simulates the finite element model of the corresponding structure; the operation period divides and establishes bridge finite element models with different aging degrees according to the intensity of material aging in different years within the service life of the bridge.

[0016] Preferably, the multi-stage finite element model is numerically simulated using the Opensees formula; the earthquake hazard curve is obtained by linear fitting of local earthquake frequency records; based on the earthquake hazard curve, the seismic response of the bridge structure under each earthquake wave is calculated using the cloud diagram method, and a probabilistic seismic demand model is obtained through regression analysis; a nonlinear time history analysis is performed on the structural seismic probabilistic demand of the component at each stage and the key working conditions during the construction process to obtain a staged probabilistic seismic demand model (PSDM):

[0017] H IM (IM) = k0IM -k(3.1)

[0018] S D (i) = a(i)(IM) b(i) (3.2)

[0019] Among them, k0, k, a, b, c are fitting coefficients; IM represents the intensity of each seismic wave, and the maximum acceleration in each seismic wave is selected as the fitting data; i represents the calculation at different stages; among them, H IM represents the probability of an earthquake with an intensity of IM recorded locally; S D It represents the displacement, curvature deformation and other seismic responses of the structure generated by each seismic wave, which are calculated as the demand of the structure under earthquake action.

[0020] Preferably, the material degradation model includes a time-varying steel bar strength model;

[0021] The time-varying steel bar strength model introduces parameters for steel bar corrosion and a mathematical model for calculating the time-varying characteristics of bridge section loss rate:

[0022]

[0023] A0 is the cross-sectional area of ​​the steel bar before corrosion occurs; A(t) represents the cross-sectional area of ​​the steel bar after corrosion occurs;

[0024] A(t)=A0-r corr (tT i ) (4.2)

[0025] T i Represents the time when steel bar corrosion begins. Steel bar corrosion begins after the concrete cover fails. Under normal circumstances, T i Take 10 years, and 6 years for coastal environment;

[0026] r corr The calculation formula for steel corrosion rate is obtained by referring to Stewat:

[0027]

[0028] Where w / c is the water-cement ratio in concrete making, and C is the thickness of the concrete cover;

[0029] Preferably, the component capacity degradation model is obtained by calculating the section capacity based on the steel bar strength time-varying model data, and the capacity of the section after degradation over the years is calculated over a span of ten years as a capacity sample for multi-stage vulnerability analysis.

[0030] Preferably, a probabilistic earthquake demand model is obtained by performing nonlinear analysis on the multi-stage finite element model. The model is repeatedly calculated under different component capacity degradation states, and vulnerability curves of different stages are plotted. The vulnerability curves are then convolved with the earthquake hazard model to obtain the earthquake damage risk probability distribution. The calculation formula for the earthquake damage risk probability value at stage i is as follows:

[0031]

[0032] P i [S D ≥S C |IM] represents the probability distribution function of the structural earthquake response damage state D under a certain earthquake intensity IM; the specific expansion is as follows:

[0033]

[0034] i means that in stage i, β d is the standard deviation between the fitting result of the earthquake probability demand model and the actual value in this stage; dH IM (IM) represents the derivative of the earthquake hazard curve obtained by linear fitting of the local earthquake frequency record.

[0035] Preferably, the vulnerability curve of the bridge at each stage is convolved with the earthquake hazard curve to obtain the probability value of the earthquake risk of the bridge at that stage; then, nonlinear fitting is performed according to the change of the probability value of different stages over time in the following form to obtain the calculation formula of the bridge damage probability curve with time as the variable as follows:

[0036] P(t)=a*t 1.5 +b*t+c (7.1)

[0037] a, b, and c are all fitting parameters.

[0038] Preferably, the calculation method of the post-earthquake repair cost is based on the full bridge repair cost estimation method of the components, that is, it is obtained by summing the repair costs of each component, as shown in the following formula:

[0039]

[0040] Where: C d / id is the maintenance cost of the entire bridge; n c is the total number of component types; n cd is the total number of damage types of similar components; n cde is the total number of components of the same type with the same damage type; R[] is the cost calculation function of different strategies under a certain maintenance standard; λ cd (l) is the seismic risk probability value of the component under the damage type d and damage state l of the type C component, which is determined according to formula (8.1).cdk (l) is the probability of selecting repair method k for type c component under damage type d and damage state l;

[0041] Preferably, the time-varying distribution curves of the average annual cost risk at different stages are fitted according to the risk values ​​calculated at different stages according to the following formula, and the formulas for the time-varying distribution curves of the average annual cost risk at different stages are as follows:

[0042]

[0043] a1, a2, a3, b1, b2, c1, c2, and d are the fitting parameters of the risk costs of the construction and operation stages over time, respectively, and T represents the duration of the construction stage.

[0044] Preferably, the construction phase earthquake risk time-varying curve is integrated to obtain the construction phase risk value, and its risk value proportion in the entire life cycle is calculated; the construction earthquake risk value proportion under different construction times is simulated, and the construction time when the proportion value exceeds q% is the construction earthquake risk warning value, and the value of k is defined according to the investor's needs or relevant specifications;

[0045] The risk calculation formula is as follows:

[0046]

[0047] λ is the risk value, T0 is the duration;

[0048] The formula for the construction earthquake risk warning value is as follows:

[0049] T λq =T(λ s / λ>q%) (10.2)

[0050] T λq is the construction earthquake risk warning value, T(λ s / λ>q%) is the construction phase risk λ s The construction time corresponding to a total risk of q%.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) The technical solution provided by the present invention takes into account the construction stages and construction methods of the bridge, and more accurately evaluates the earthquake risk cost of the bridge for different bridges and different construction processes.

[0053] (2) The technical solution provided by the present invention takes into account the influence of the seismic zoning and atmospheric environment of the location of the bridge, and conducts bridge seismic risk assessment tailored to local conditions for bridges in different seismic zones and climates, and has wide regional applicability.

[0054] (3) The technical solution provided by the present invention clearly represents the changes in the damage probability distribution and risk distribution of the bridge at different stages throughout its life cycle using a fitting curve, which is concise and intuitive.

[0055] (4) The technical solution provided by the present invention is highly flexible in the budget assessment scheme for bridge earthquake damage. It can adjust the calculation according to the standards and construction schedules of different regions and compare the risk differences of different construction plans.

[0056] (5) The construction warning value provided by this technical solution provides a reference for the acceptable range of seismic risk during the construction phase. The construction time can be adjusted based on this warning value, thereby reducing the earthquake risk of the bridge to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 is a flow chart of the method of the present invention.

[0058] Figure 2 Schematic diagram of bridge construction using different construction methods of the present invention.

[0059] Figure 3 This is a graph showing changes in the steel bar corrosion area of ​​the present invention.

[0060] Figure 4 This is the bridge component capacity degradation model of the present invention.

[0061] Figure 5 The bridge component earthquake probability demand model of the present invention is

[0062] Figure 6 Vulnerability curves of key parts of piers at different stages.

[0063] Figure 7 Fitting curve for component seismic risk probability value.

[0064] Figure 8 It is the average annual distribution curve of bridge seismic risk throughout its life cycle.

[0065] Figure 9 Comparison of the average annual distribution of seismic risk for bridges with different construction methods.

[0066] Figure 10 This is a graph showing the proportion of seismic risk values ​​for bridges throughout their life cycle.

[0067] Figure 11 Comparison of seismic risk values ​​of bridges over their entire life cycle under different working conditions.

[0068] Figure 12 Simulation diagram of construction earthquake risk ratio under different construction plan times. DETAILED DESCRIPTION

[0069] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0070] Example 1

[0071] like Figure 1 A bridge earthquake risk cost assessment method considering the construction and operation periods is shown in

[0072] S1: Determine the basic elements of the bridge construction plan; the basic elements include bridge type, construction method, bridge atmospheric environment, bridge site intensity zoning and bridge service life;

[0073] S2: Establish a multi-stage finite element model based on the bridge type and the corresponding construction method;

[0074] S3: The bridge environment includes a seismic environment and an atmospheric environment; an earthquake hazard curve is established based on the seismic environment of the bridge; and a steel bar degradation model inside the bridge is established based on the atmospheric environment of the bridge;

[0075] S4: After calculating the nonlinear time history response of all models using the cloud diagram method, the multi-stage finite element model is fitted with the seismic wave logarithm of the earthquake hazard curve to establish a probabilistic earthquake demand model;

[0076] S5: The steel bar degradation model is combined with the service life of the bridge according to the material degradation model to calculate the component capacity degradation model;

[0077] S6: The probabilistic seismic demand model is combined with the component capacity degradation model, and the seismic responses of the degraded components are calculated in sequence. The demand model is updated, and the fragility curve is plotted and convolved with the seismic risk curve to obtain a multi-stage seismic risk probability distribution model for the bridge.

[0078] S7: Draw a time-varying curve for the earthquake risk of a bridge over its entire life cycle; import the cost data and repair time data from the bridge earthquake damage budget list into the probability distribution formula for bridge damage at all stages, and obtain the time-varying curves for the direct and indirect costs of bridge earthquake disasters through conditional probability calculations;

[0079] S8: Evaluate the earthquake risk warning value of construction factors; preset the completion time of the bridge through the construction schedule, and use the completion time of the bridge's earthquake disaster cost time-varying curve to a certain percentage of the entire life cycle as the warning value. If the construction time is greater than the warning value, it indicates that the earthquake risk in the construction process needs to be taken seriously, and relevant earthquake-resistant measures should be taken to reduce losses.

[0080] The multi-stage bridge model includes the construction period and operation period of the bridge; during the construction period, the bridge construction process is divided into multiple stages according to the construction plan, and the finite element model of the corresponding structure is simulated; during the operation period, the finite element model of the bridge with different aging degrees is established according to the intensity of material aging in different years within the bridge's service life.

[0081] The multi-stage finite element model was numerically simulated using the Opensees formula. The seismic hazard curve was obtained by linearly fitting local earthquake frequency records. Based on the seismic hazard curve, the seismic response of the bridge structure under each earthquake wave was calculated using the cloud diagram method, and a probabilistic seismic demand model was obtained through regression analysis. Nonlinear time history analysis was performed on the structural seismic probabilistic demand at each stage of the component and the key working conditions during the construction process to obtain a staged probabilistic seismic demand model (PSDM):

[0082] H IM (IM) = k0IM -k (3.1)

[0083] S D (i) = a(i)(IM) b(i) (3.2)

[0084] Among them, k0, k, a, b, c are fitting coefficients; IM represents the intensity of each seismic wave, and the maximum acceleration in each seismic wave is selected as the fitting data; i represents the calculation at different stages; among them, H IM represents the probability of an earthquake with an intensity of IM recorded locally; S D It represents the displacement, curvature deformation and other seismic responses of the structure generated by each seismic wave, which are calculated as the demand of the structure under earthquake action.

[0085] Material degradation models include time-varying reinforcement strength models;

[0086] The time-varying steel bar strength model introduces parameters for steel bar corrosion and a mathematical model for calculating the time-varying characteristics of bridge section loss rate:

[0087]

[0088] A0 is the cross-sectional area of ​​the steel bar before corrosion occurs; A(t) represents the cross-sectional area of ​​the steel bar after corrosion occurs;

[0089] A(t)=A0-r corr (tT i ) (4.2)

[0090] T iRepresents the time when steel bar corrosion begins. Steel bar corrosion begins after the concrete cover fails. Under normal circumstances, T i Take 10 years, and 6 years for coastal environment;

[0091] r corr The calculation formula for steel corrosion rate is obtained by referring to Stewat:

[0092]

[0093] Where w / c is the water-cement ratio in concrete making, and C is the thickness of the concrete cover;

[0094] The component capacity degradation model is obtained by calculating the section capacity based on the time-varying model data of steel bar strength. The capacity of the section after degradation over the years is calculated over a span of ten years and used as the capacity sample for multi-stage fragility analysis.

[0095] The fragility curves of the bridge at each stage are convolved with the earthquake hazard curve to obtain the probability value of the bridge earthquake risk at that stage. Based on the time-varying probability values ​​of different stages, nonlinear fitting is performed using the following formula to obtain the bridge damage probability curve with time as the variable:

[0096] P(t)=a*t 1.5 +b*t+c (7.1)

[0097] a, b, and c are all fitting parameters.

[0098] The calculation method for post-earthquake repair costs is based on the full-bridge repair cost estimation method for components, that is, it is obtained by summing the repair costs of each component, as shown in the following formula:

[0099]

[0100] Where: C d / id is the maintenance cost of the entire bridge; n c is the total number of component types; n cd is the total number of damage types of similar components; n cde is the total number of components of the same type with the same damage type; R[] is the cost calculation function of different strategies under a certain maintenance standard; λ cd (l) is the seismic risk probability value of the component under the damage type d and damage state l of the type C component, which is determined according to formula (8.1). cdk (l) is the probability of selecting repair method k for type c component under damage type d and damage state l;

[0101] The time-varying distribution curves of the average annual cost risk at different stages are fitted according to the risk values ​​calculated at different stages using the following formula. The formulas for the time-varying distribution curves of the average annual cost risk at different stages are as follows:

[0102]

[0103] a1, a2, a3, b1, b2, c1, c2, and d are the fitting parameters of the risk costs of the construction and operation stages over time, respectively, and T represents the duration of the construction stage.

[0104] A probabilistic seismic demand model was obtained by performing nonlinear analysis on the multi-stage finite element model. The model was repeatedly calculated under different component degradation states to plot vulnerability curves for different stages. The vulnerability curves were then convolved with the earthquake hazard model to obtain the earthquake damage risk probability distribution. The earthquake damage risk probability value at stage i was calculated as follows:

[0105]

[0106] P i [S D ≥S C |IM] represents the probability distribution function of the structural earthquake response damage state D under a certain earthquake intensity IM; the specific expansion is as follows:

[0107]

[0108] i means that in stage i, β d is the standard deviation between the fitting result of the earthquake probability demand model and the actual value in this stage; dH IM (IM) represents the derivative of the earthquake hazard curve obtained by linear fitting of the local earthquake frequency record.

[0109] The construction phase earthquake risk time-varying curve is integrated to obtain the construction phase risk value, and its risk value proportion in the entire life cycle is calculated; the construction earthquake risk value proportion under different construction times is simulated, and the construction time when the proportion value exceeds q% is the construction earthquake risk warning value. The value of k is defined according to the investor's needs or relevant specifications;

[0110] The risk calculation formula is as follows:

[0111]

[0112] λ is the risk value, T0 is the duration;

[0113] The formula for the construction earthquake risk warning value is as follows:

[0114] T λq =T(λ s / λ>q%) (10.2)

[0115] T λq is the construction earthquake risk warning value, T(λs / λ>q%) is the construction phase risk λ s The construction time corresponding to a total risk of q%.

[0116] Example 2

[0117] A widely constructed three-span concrete continuous beam bridge was selected. The span arrangement was (65m + 98m + 65m). The piers were 21.5m high, with Y-shaped rectangular columns measuring 6.4m x 2.5m at the base. The main beams were prestressed concrete composite box girders with corrugated steel webs. The concrete was C50, and the corrugated steel webs were Q345D. The piers were constructed with C40 concrete and HRB400 steel. The main pier supports were QZ series spherical bearings.

[0118] like Figure 2 Several optional construction methods are shown during the construction phase of the bridge: Figure 2 (a) is the full-house bracket method; Figure 2 (b) Prefabrication and hoisting method; Figure 2 (c) is the cantilever casting method.

[0119] Establish a finite element model and perform nonlinear time history analysis: Figure 3 shown.

[0120] Calculate the steel bar corrosion area change diagram for this application. The required data calculation method is as follows

[0121] Corrosion rate, w / c is the water-cement ratio in concrete production, which is 0.41, and C is the thickness of the concrete cover, which is 40 mm. Substitute it into formula (4.6) to calculate the corrosion rate. In addition, this value can be taken as 0.005 m in coastal areas and 0.001 m in inland dry areas as a reference.

[0122] The time for steel bar corrosion to begin is after the concrete cover fails, which is 10 years in general environment and 6 years in coastal environment;

[0123] Substitute the corrosion rate and the time when corrosion starts into formula (4.5) and formula (4.4) respectively, and jointly obtain the material strength degradation data, that is, the steel bar corrosion area change graph.

[0124] like Figure 4 As shown in the figure, the cross-section capacity time-varying model is calculated using the xtract software through the material time-varying model data.

[0125] like Figure 5 As shown in the figure, the models under different cross-sectional capacities use the nonlinear time history analysis results to establish the probabilistic seismic demand model of bridge components. The linear fitting values ​​of the time history analysis data and the seismic motion are obtained as shown in the following table:

[0126]

[0127] like Figure 6 As shown in Figure 2, the fragility curves of four types of damage states at the bottom of the pier under different working conditions and years are calculated by substituting the fitting results of each year into the fragility formula.

[0128] The earthquake risk probability values ​​P at different stages are obtained by convolution operation with the local earthquake probability distribution using formula (6.1). f

[0129] According to formula (7.1), the fitting distribution of component seismic risk probability value is obtained; the results are as follows Figure 7

[0130] Formula (6.1) is used to calculate the risk cost: Life cycle bridge earthquake risk cost = earthquake damage probability of the bridge at each stage * earthquake damage repair cost;

[0131] According to the above formula, the risk cost of the numerical value is converted into the fitting distribution of the earthquake risk cost of the bridge constructed by cantilever casting method throughout the whole life cycle. Figure 8 As shown;

[0132] Repeat the above steps, and the calculation results of different construction methods are as follows: Figure 9 .

[0133] The fitting result of risk cost is integrated over time using formula (7.1) at different stages to calculate the risk value, λ id is the indirect cost, the loss of time, λ d Is a direct cost such as Figure 10 .

[0134] The ratio of construction risk to total risk under different simulated construction times is as follows: Figure 11 , and conduct multi-condition simulation on the calculation results. Figure 12 , determine the construction earthquake risk warning time as follows:

[0135]

[0136]

[0137] As mentioned above, the results of bridge seismic risk analysis at different stages vary depending on a variety of factors. This study examines the sensitivity of bridge seismic risk costs to these factors. The primary factor influencing bridge seismic risk during the construction phase is the construction method, while the primary factor during the operation phase is the bridge's environment, including the local earthquake frequency, atmospheric conditions, and chloride ion content (in coastal areas).

[0138] Of course, it will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, but also encompasses the same or similar structures that can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and it is intended that all variations that fall within the meaning and range of equivalents of the claims be encompassed within the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0139] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0140] The technology, shape, and structure not described in detail in the present invention are all well-known technologies.

Claims

1. A bridge earthquake risk cost assessment method considering the construction and operation periods, characterized by: include S1: Determine the basic elements of the bridge construction plan; the basic elements include bridge type, construction method, bridge atmospheric environment, bridge site intensity zoning and bridge service life; S2: Establish a multi-stage finite element model based on the bridge type and the corresponding construction method; S3: The bridge environment includes a seismic environment and an atmospheric environment; an earthquake hazard curve is established based on the seismic environment of the bridge; and a steel bar degradation model inside the bridge is established based on the atmospheric environment of the bridge; S4: After calculating the nonlinear time history response of all models using the cloud diagram method, the multi-stage finite element model is fitted with the seismic wave logarithm of the earthquake hazard curve to establish a probabilistic earthquake demand model; S5: The steel bar degradation model is combined with the service life of the bridge according to the material degradation model to calculate the component capacity degradation model; S6: The probabilistic seismic demand model is combined with the component capacity degradation model, and the seismic responses of the degraded components are calculated in sequence. The demand model is updated, and the fragility curve is plotted and convolved with the seismic risk curve to obtain a multi-stage seismic risk probability distribution model for the bridge. S7: Draw a time-varying curve for the earthquake risk of a bridge over its entire life cycle; import the cost data and repair time data from the bridge earthquake damage budget list into the probability distribution formula for bridge damage at all stages, and obtain the time-varying curves for the direct and indirect costs of bridge earthquake disasters through conditional probability calculations; S8: Evaluate the earthquake risk warning value of construction factors; preset the completion time of the bridge through the construction schedule, and use the completion time of the bridge's earthquake disaster cost time-varying curve to a certain percentage of the entire life cycle as the warning value. If the construction time is greater than the warning value, it indicates that the earthquake risk in the construction process needs to be taken seriously, and relevant earthquake-resistant measures should be taken to reduce losses.

2. A bridge earthquake risk cost assessment method considering construction and operation periods according to claim 1, characterized in that: The multi-stage bridge model includes the construction period and operation period of the bridge; the construction period divides the bridge construction process into multiple stages according to the construction plan and simulates the finite element model of the corresponding structure; the operation period divides and establishes bridge finite element models with different aging degrees according to the intensity of material aging in different years within the bridge's service life.

3. A bridge earthquake risk cost assessment method considering construction and operation periods according to claim 2, characterized in that: The multi-stage finite element model was numerically simulated using the Opensees formula. The seismic hazard curve was obtained by linear fitting of local earthquake frequency records. Based on the seismic hazard curve, the seismic response of the bridge structure under each earthquake wave was calculated using the cloud diagram method, and a probabilistic seismic demand model was obtained through regression analysis. Nonlinear time history analysis was performed on the structural seismic probabilistic demand of the components at each stage and the key working conditions during the construction process to obtain a staged probabilistic seismic demand model (PSDM): H IM (IM)=k0IM -k (3.1) S D (i)=a(i)(IM) b(i) (3.2) Among them, k0, k, a, b, c are fitting coefficients; IM represents the intensity of each seismic wave, and the maximum acceleration in each seismic wave is selected as the fitting data; i represents the calculation at different stages; among them, H IM represents the probability of an earthquake with an intensity of IM recorded locally; S D It represents the displacement, curvature deformation and other seismic responses of the structure generated by each seismic wave, which are calculated as the demand of the structure under earthquake action.

4. A bridge earthquake risk cost assessment method considering construction and operation periods according to claim 3, characterized in that: The material degradation model includes a time-varying steel bar strength model; The time-varying steel bar strength model introduces parameters for steel bar corrosion and a mathematical model for calculating the time-varying characteristics of bridge section loss rate: A0 is the cross-sectional area of ​​the steel bar before corrosion occurs; A(t) represents the cross-sectional area of ​​the steel bar after corrosion occurs; A(t)=A0-r corr (t-T i ) (4.2) T i Represents the time when steel bar corrosion begins. Steel bar corrosion begins after the concrete cover fails. Under normal circumstances, T i Take 10 years, and 6 years for coastal environment; r corr The calculation formula for steel corrosion rate is obtained by referring to Stewat: Where w / c is the water-cement ratio in concrete making, and C is the thickness of the concrete cover.

5. A bridge earthquake risk cost assessment method considering construction and operation periods according to claim 4, characterized in that: The component capacity degradation model is obtained by calculating the section capacity based on the time-varying model data of the steel bar strength. The capacity of the section after degradation over the years is calculated with a span of ten years as a capacity sample for multi-stage fragility analysis.

6. A bridge earthquake risk cost assessment method considering construction and operation periods according to claim 5, characterized in that: A probabilistic seismic demand model was obtained by performing nonlinear analysis on the multi-stage finite element model. The model was repeatedly calculated under different component degradation states to plot vulnerability curves for different stages. The vulnerability curves were then convolved with the earthquake hazard model to obtain the earthquake damage risk probability distribution. The earthquake damage risk probability value at stage i was calculated as follows: P i [S D ≥S C |IM] represents the probability distribution function of the structural earthquake response damage state D under a certain earthquake intensity IM; the specific expansion is as follows: i means that in stage i, β d is the standard deviation between the fitting result of the earthquake probability demand model and the actual value in this stage; dH IM (IM) represents the derivative of the earthquake hazard curve obtained by linear fitting of the local earthquake frequency record.

7. The bridge earthquake risk cost assessment method considering the construction and operation periods according to claim 5 is characterized in that: The fragility curve of the bridge at each stage is convolved with the earthquake hazard curve to obtain the probability value of the bridge earthquake risk at that stage; then, according to the change of the probability value of different stages over time, a nonlinear fitting is performed in the following form to obtain the calculation formula of the bridge damage probability curve with time as the variable: P(t)=a*t 1.5 +b*t+c (7.1) a, b, and c are all fitting parameters.

8. The bridge earthquake risk cost assessment method considering the construction and operation periods according to claim 6 is characterized in that: The calculation method for post-earthquake repair costs is based on the full-bridge repair cost estimation method for components, that is, it is obtained by summing the repair costs of each component, as shown in the following formula: Where: C d / id is the maintenance cost of the entire bridge; n c is the total number of component types; n cd is the total number of damage types of similar components; n cde is the total number of components of the same type with the same damage type; R[] is the cost calculation function of different strategies under a certain maintenance standard; λ cd (l) is the seismic risk probability value of the component under the damage type d and damage state l of the type C component, which is determined according to formula (8.1). cdk (l) is the probability of selecting maintenance method k for type c component under damage type d and damage state l.

9. The bridge earthquake risk cost assessment method considering the construction and operation periods according to claim 7 is characterized in that: The time-varying distribution curves of the average annual cost risk at different stages are fitted according to the risk values ​​calculated at different stages according to the following formula, and the formulas for the time-varying distribution curves of the average annual cost risk at different stages are as follows: a1, a2, a3, b1, b2, c1, c2, and d are the fitting parameters of the risk costs of the construction and operation stages over time, respectively, and T represents the duration of the construction stage.

10. The bridge earthquake risk cost assessment method considering the construction and operation periods according to claim 6 is characterized in that: The construction phase earthquake risk time-varying curve is integrated to obtain the construction phase risk value, and its risk value proportion in the entire life cycle is calculated; the construction earthquake risk value proportion under different construction times is simulated, and the construction time when the proportion value exceeds q% is the construction earthquake risk warning value. The value of k is defined according to the investor's needs or relevant specifications; The risk calculation formula is as follows: λ is the risk value, T0 is the duration; The formula for the construction earthquake risk warning value is as follows: T λq =T(λ S / λ>q%) (10.2) T λq is the construction earthquake risk warning value, T(λ S / λ>q%) is the construction time corresponding to when the construction phase risk λs accounts for q% of the total risk.

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