Design method of simply supported steel structure aqueduct

Abstract

The invention relates to the technical field of water conservancy projects, in particular to a design method of a simply-supported steel structure aqueduct. The method comprises the following steps: determining the engineering grade and scale of the aqueduct; the flow velocity, the hydraulic slope and the wetted perimeter are set and designed, and the water-passing section area of the trough body is calculated; drawing up the depth-to-width ratio and clearance of the cross section of the trough body, and determining the size of the water-passing cross section; checking the head loss; drawing up the section size of a steel structure aqueduct, and determining the flexural capacity, the design load and the design bending moment of the steel structure; determining a suggested span of the structure; checking the section size of the steel structure aqueduct; stiffening ribs and diaphragm plates are arranged for the steel structure; checking the principal stress intensity of the steel structure aqueduct; checking the overall stability and the local stability of the steel structure; and the aqueduct body is subjected to anti-corrosion design and water stop design. The method has remarkable effects and effects in the aspects of improving design efficiency, enhancing design reliability, optimizing structural performance, adapting to complex working conditions, filling a standard blank, prolonging the engineering life and the like.

Description

Technical Field

[0001] The present application relates to the technical field of water conservancy engineering, and in particular to a design method for a simply supported steel structure aqueduct. Background Art

[0002] Aqueducts are hydraulic structures used to span lines, ditches, and canyons in water diversion projects, thereby achieving their purpose. In recent years, water conservancy projects have emerged and experienced continuous breakthroughs. Aqueduct structures have also continued to diversify.

[0003] Due to the restrictions of water conservancy industry regulations, the span range of prestressed aqueducts is 25m to 50m, and spans of 50m to 100m usually require the use of arch-type and other structural types. Aqueducts with special structural types do not have competitive advantages in construction and cost.

[0004] With the development of the water conservancy industry, aqueduct structures have transitioned from concrete materials to steel materials. However, for the design and verification of aqueducts, concrete aqueducts can refer to the "Design Code for Hydraulic Concrete Structures" (SL 191-2008), but there is no calculation basis for steel structure aqueducts.

[0005] While the construction and highway bridge industries both have comprehensive regulatory frameworks to guide the design of concrete and steel structures, the water conservancy industry lacks a basis for calculating steel aqueducts. This lack of a regulatory framework leaves the design of steel aqueducts without a theoretical basis. If a project requires a steel aqueduct, the design lacks guidance and theoretical calculation methods, resulting in unreliable and potentially unsafe structures. Summary of the Invention

[0006] The present application provides a design method for a simply supported steel structure aqueduct, aiming to solve at least one of the technical problems existing in the background technology.

[0007] This application is implemented through the following technical solutions:

[0008] A design method for a simply supported steel structure aqueduct includes the following contents:

[0009] Determine the engineering grade and scale of the aqueduct based on planning conditions and functional requirements;

[0010] Hydraulic design: Develop the design flow rate, hydraulic gradient, and wetted perimeter. Calculate the cross-sectional area of the flume body based on the design flow rate, hydraulic gradient, and wetted perimeter. Develop the depth-to-width ratio and clearance of the flume body section to determine the dimensions of the cross-sectional area. Verify that the head loss meets the design standards. If so, set the hydraulic gradient, depth-to-width ratio, and clearance to the corresponding design values. Otherwise, repeat the hydraulic design steps.

[0011] Structural design: Draft the cross-sectional dimensions of the steel structure aqueduct, and determine the steel structure's bending capacity, design load, and design bending moment based on the cross-sectional dimensions. Determine the recommended span of the structure based on the design bending moment and the steel structure's bending capacity. Verify that the proposed cross-sectional dimensions of the steel structure aqueduct meet construction space and structural requirements. If not, repeat the structural design steps.

[0012] According to the cross-sectional dimensions of the steel structure aqueduct, stiffening ribs and diaphragms are provided for the steel structure;

[0013] Structural verification: Verify the principal stress strength of the steel structure aqueduct; verify the overall stability and local stability of the steel structure respectively. The local stability verification includes the stiffening rib stiffness verification, stiffening rib spacing verification, stiffening rib inertia moment verification and diaphragm bearing strength verification; and perform anti-overturning verification on the aqueduct body.

[0014] After all calculations meet the specifications, the aqueduct body will be designed for corrosion protection and water stopping.

[0015] The design method of a simply supported steel structure aqueduct provided in this application comprehensively optimizes the design process of a simply supported steel structure aqueduct, significantly improves the design efficiency, can quickly determine the engineering grade, scale, hydraulic parameters and structural dimensions of the aqueduct, and avoids the blindness and repetitiveness in traditional design methods. At the same time, through the head loss verification in the hydraulic design and multiple verification steps in the structural design, the rationality of the design parameters and the safety of the structure are ensured, and the reliability of the design is further enhanced. In the structural design, the stiffening ribs and diaphragms are reasonably set, and the stiffness, arrangement spacing, moment of inertia, etc. of the stiffening ribs are verified in detail, which effectively improves the stability and bearing capacity of the steel structure and optimizes the structural performance. In addition, this method is applicable to aqueduct projects with different planning conditions and functional requirements. It can flexibly adjust the design parameters according to the specific engineering conditions and adapt to various complex working conditions. It has strong versatility and adaptability, fills the gap in the lack of normative basis for the design of steel structure aqueducts, and provides theoretical support and practical guidance for the design and construction of steel structure aqueducts. Through anti-corrosion and water-stopping designs, the durability and impermeability of the aqueduct body are enhanced, the service life of the aqueduct is extended, and the maintenance cost of the project is reduced. Therefore, this application has significant effects and effects in improving design efficiency, enhancing design reliability, optimizing structural performance, adapting to complex working conditions, filling gaps in specifications, and extending the life of the project, providing strong technical support for the design and construction of simply supported steel aqueducts.

[0016] In some optional embodiments, in water conservancy design, the calculation formula for the water flow section is as follows:

[0017]

[0018] In formulas (1) and (2), V is the design flow velocity, n is the roughness coefficient, R is the hydraulic radius, S is the hydraulic slope, A is the cross-sectional area of the water flow, and p ... w is the wetted perimeter, i.e. the length of the portion where the water flow contacts the solid boundary.

[0019] In some optional embodiments, the recommended span of the structure is determined by the following formula:

[0020] M x =γ x Wf(3)

[0021] q=γ1q1+γ2q2+γ3q3(4)

[0022]

[0023] In formulas (3), (4), and (5), Mx is the bending bearing capacity, W is the gross section modulus of the component, f is the design strength of the steel, and γ x is the plastic development coefficient of the aqueduct section, q is the design load, q1 is the deadweight of the steel structure, q2 is the weight of water, q2 = Aρ, where ρ is the density of water, A is the volume of water, q3 is the maintenance crowd load, γ0 is the structural importance coefficient, γ1 is the structural deadweight partial coefficient, γ2 is the structural water load partial coefficient, γ3 is the structural crowd load partial coefficient, l0 is the structural calculation span, and M is the design bending moment;

[0024] Let M≤M x The preliminary cross-sectional dimensions and the recommended span of the structure that meets the cross-sectional conditions can be solved.

[0025] In some optional embodiments, the principal stress strength of the steel structure aqueduct is calculated using the following formula:

[0026]

[0027] h0τ≤f vd (7)

[0028]

[0029] In formulas (6), (7), and (8), γ0 is the structural importance coefficient, σ x is the design value of normal stress, M y Design value of bending moment, W y,eff Effective section modulus, f d The design value of flexural strength, τ is the design value of shear stress, f vd is the design value of shear strength.

[0030] In some optional embodiments, if the conditions are met:

[0031] Among them, h is the height of the tank body, f y is the yield strength of steel, b0 is the center distance of web, L1 is the lateral support spacing of compression flange;

[0032] There is no need to verify the overall stability of the steel structure.

[0033] In some optional embodiments, the overall stability is verified using the following formula:

[0034]

[0035] M Rd,y =W y,eff f d (11)

[0036] M Rd,z =W z,eff f d (12)

[0037]

[0038] In formulas (9), (10), (11), (12), and (13), γ0 is the structural importance coefficient, which is 1.1, and M y 、M z is the maximum bending moment of the member around the y-axis and the z-axis, β m,y , γ m,z is the corresponding bending moment M y 、M z The equivalent bending moment coefficient, is the relative slenderness ratio of the member around the y-axis and the z-axis, X LT,z 、X LT,y M z and M y The overall stability reduction factor of the bending-torsional instability mode of the component around the y-axis and the z-axis under the action of the bending moment in the action plane alone, W y,eff 、W z,eff is the effective section modulus of the component around the y-axis and z-axis, M cr,y 、M cr,z M y and M z The overall flexural-torsional elastic buckling moment of the component about the y-axis and z-axis considering the influence of constraints under the action of the bending moment in the action plane alone, M Rd,y 、M Rd,z is the cross-sectional bending capacity of the member around the y-axis and the z-axis considering local buckling, f d is the design value of bending strength, f y is the yield strength of steel.

[0039] In some optional embodiments, the stiffening ribs include longitudinal stiffening ribs and transverse stiffening ribs, and the longitudinal stiffening ribs and transverse stiffening ribs satisfy a width-to-thickness ratio of:

[0040] Among them, h s is the width of the longitudinal stiffener or transverse stiffener, t s is the thickness of the longitudinal stiffener or transverse stiffener, f y is the yield strength of steel.

[0041] In some optional embodiments, the stiffness of the compression stiffener is calculated using the following formula:

[0042]

[0043] n=n l +1 (19)

[0044] In formulas (14), (15), (16), (17), (18), and (19), γ l is the relative stiffness of the longitudinal stiffener, Among them, I l is the bending inertia moment of a single longitudinal stiffener about the main axis of the stiffener plate, b is the calculated width of the longitudinal stiffener plate / transverse stiffener plate, and E is the elastic modulus of the steel;

[0045] γ t is the relative stiffness of the transverse stiffener, Among them, I t is the bending inertia moment of a single transverse stiffener about the main axis of the stiffener plate, a is the calculated length of the longitudinal stiffener plate / transverse stiffener plate;

[0046] t is the thickness of the motherboard, a t is the transverse stiffener spacing, α is the aspect ratio of the longitudinal stiffener plate / transverse stiffener plate;

[0047] δ l is the ratio of the cross-sectional area of a single longitudinal stiffener to the area of the base plate, Among them, A s,l is the cross-sectional area of a single longitudinal stiffener;

[0048] D is the width of the one-way slab, Among them, υ is Poisson's ratio, which is 0.3;

[0049] n l The number of longitudinal stiffeners is arranged at equal intervals.

[0050] In some optional embodiments, the stiffening rib arrangement spacing verification includes top plate compression stiffening rib arrangement spacing verification, bottom plate tension stiffening rib arrangement spacing verification, and transverse stiffening rib arrangement spacing verification;

[0051] The following formula is used to calculate the spacing of the top plate compression stiffeners:

[0052] l l ≤40t f (20)

[0053] In formula (20), l l is the stiffener spacing, t f is the flange thickness;

[0054] The spacing of the tensile stiffeners in the bottom plate is calculated using the following formula:

[0055] a≤80t f (twenty one)

[0056] In formula (21), a is the spacing between stiffeners, t f is the flange thickness;

[0057] The following formula is used to check the spacing of transverse stiffeners:

[0058] a≤1.5h w (twenty two)

[0059] In formula (22), h w is the net height of the web, and a is the spacing between stiffeners.

[0060] In some optional embodiments, the stiffener moment of inertia calculation includes the transverse stiffener moment of inertia calculation and the web longitudinal stiffener moment of inertia calculation;

[0061] The moment of inertia of the transverse stiffener is calculated using the following formula:

[0062]

[0063] In formula (23), t w is the web thickness, h w is the net height of the web, I t is the moment of inertia of the transverse stiffener;

[0064] The moment of inertia of the longitudinal stiffener of the web is calculated using the following formula:

[0065]

[0066] In formula (24), t w is the web thickness, I l Moment of inertia of the longitudinal web stiffener, h w is the net height of the web, Where a is the spacing between the transverse stiffeners of the web.

[0067] In some optional embodiments, the spacing between the diaphragms is no greater than 3m, and the diaphragms are provided with supporting stiffening ribs. The compressive strength of the diaphragms is calculated using the following formula:

[0068]

[0069] In formulas (25) and (26), γ0 is the structural importance coefficient, which is 1.1, and R V is the support reaction, A S is the sum of the supporting stiffener areas, B eb is the effective calculation width of the web under local pressure, t w is the web thickness, f cd is the design value of steel compressive strength, B ev is the effective width of the web, f d is the design value of steel strength.

[0070] In some optional embodiments, the anti-overturning calculation of the tank body adopts the following formula:

[0071]

[0072] In formula (27), k qf is the lateral anti-overturning stability coefficient, take k qf =2.5,∑S bk,i The design value of the effect of the basic combination of actions (the partial coefficient is 1) to stabilize the superstructure, ∑S sk,i The design value of the effect of the basic combination of actions (partial coefficient is 1) that causes the superstructure to become unstable.

[0073] Compared with the prior art, this application has the following advantages and beneficial effects:

[0074] The design method of a simply supported steel structure aqueduct provided in this application comprehensively optimizes the design process of a simply supported steel structure aqueduct, significantly improves the design efficiency, can quickly determine the engineering grade, scale, hydraulic parameters and structural dimensions of the aqueduct, and avoids the blindness and repetitiveness in traditional design methods. At the same time, through the head loss verification in the hydraulic design and multiple verification steps in the structural design, the rationality of the design parameters and the safety of the structure are ensured, and the reliability of the design is further enhanced. In the structural design, the stiffening ribs and diaphragms are reasonably set, and the stiffness, arrangement spacing, moment of inertia, etc. of the stiffening ribs are verified in detail, which effectively improves the stability and bearing capacity of the steel structure and optimizes the structural performance. In addition, this method is applicable to aqueduct projects with different planning conditions and functional requirements. It can flexibly adjust the design parameters according to the specific engineering conditions and adapt to various complex working conditions. It has strong versatility and adaptability, fills the gap in the lack of normative basis for the design of steel structure aqueducts, and provides theoretical support and practical guidance for the design and construction of steel structure aqueducts. Through anti-corrosion and water-stopping designs, the durability and impermeability of the aqueduct body are enhanced, the service life of the aqueduct is extended, and the maintenance cost of the project is reduced. Therefore, this application has significant effects and effects in improving design efficiency, enhancing design reliability, optimizing structural performance, adapting to complex working conditions, filling gaps in specifications, and extending the life of the project, providing strong technical support for the design and construction of simply supported steel aqueducts. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present application, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present application and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings:

[0076] Figure 1 A schematic diagram of a design method flow for a simply supported steel structure aqueduct provided in an embodiment of the present application;

[0077] Figure 2 A schematic diagram of the cross-sectional structure of the diaphragm provided in an embodiment of the present application;

[0078] Figure 3 A schematic diagram of the cross-sectional structure of the transverse stiffening rib provided in an embodiment of the present application;

[0079] Figure 4 This is a schematic diagram of the cross-sectional structure of the support provided in an embodiment of the present application. DETAILED DESCRIPTION

[0080] In order to make the objectives, technical solutions and advantages of this application more clear, the present application is further described in detail below in conjunction with examples and drawings. The schematic implementation methods of this application and their descriptions are only used to explain this application and are not intended to limit this application.

[0081] The present invention provides a method for designing a simply supported steel structure aqueduct. The method includes the following steps:

[0082] S1. Determine the engineering grade and scale of the aqueduct based on planning conditions and functional requirements.

[0083] During the initial design phase of a simply supported steel aqueduct, the engineering grade and scale must be determined based on specific planning conditions and functional requirements. This step forms the foundation of the entire design process, directly influencing subsequent hydraulic design, structural design, and structural verification. Planning conditions include geographic location, topography, geology, hydrology, and climate. These factors determine the aqueduct's site selection, layout, and construction plan. For example, if the aqueduct needs to span a valley or river, a longer span may be necessary; if the geological conditions are poor, a strengthened foundation may be required to ensure structural stability. Furthermore, climate conditions such as wind speed and temperature fluctuations will influence the aqueduct's structural design and material selection. Functional requirements encompass the aqueduct's primary purpose, such as water flow rate, water quality, and pressure. Water flow rate is a key parameter in determining aqueduct dimensions, directly influencing the aqueduct's cross-sectional area and structural dimensions. For example, large water flow requirements may necessitate a larger aqueduct cross-section and a more complex structural design. The water quality determines the aqueduct's corrosion protection design requirements, such as whether special anti-corrosion coatings or materials are required. The water pressure affects the structure's compressive strength and sealing design. Based on planning conditions and functional requirements, aqueducts can be classified according to national or industry standards. These engineering grades are generally categorized as Class I, Class II, and Class III, with varying design standards, construction requirements, and acceptance criteria. For example, Class I aqueducts are typically used for major water transfer projects and have higher design standards, strict construction requirements, and rigorous acceptance criteria. Class III aqueducts, on the other hand, are used for general water transfer projects and have relatively lower design standards and construction requirements. The scale of an aqueduct is determined by specific parameters such as its length, width, height, and span. These parameters not only affect the construction difficulty and cost of the aqueduct but also directly impact its operational efficiency and safety. For example, the length and span of the aqueduct need to be optimized based on the terrain and water transfer route to minimize material usage and construction costs while ensuring structural stability and water transfer efficiency. The detailed analysis and planning at this stage provide accurate input parameters for subsequent hydraulic and structural design, ensuring the scientific and rational nature of the entire design process. This not only helps improve design efficiency but also effectively reduces engineering risks, ensuring the safety and reliability of the aqueduct in long-term operation.

[0084] S2. Hydraulic Design: Determine the design flow rate, hydraulic gradient, and wetted perimeter. Calculate the cross-sectional area of the trough body based on the design flow rate, hydraulic gradient, and wetted perimeter. Determine the depth-to-width ratio and clearance of the trough body section and determine the dimensions of the cross-sectional area. Verify whether the head loss meets the design standards. If so, determine the hydraulic gradient, depth-to-width ratio, and clearance to the corresponding design values. Otherwise, repeat the hydraulic design steps.

[0085] In the embodiments of the present application, the determination of the design flow rate must comprehensively consider the water delivery efficiency and the prevention of scouring and damage to the trough body by the water flow, and is usually preliminarily estimated based on the water delivery flow and the size of the trough body. The hydraulic gradient reflects the drop of the water flow along the direction of the aqueduct, which directly affects the speed and energy loss of the water flow, and needs to be reasonably set according to the terrain conditions and water delivery requirements. The wetted perimeter refers to the length of the contact part between the water flow and the solid boundary. It is crucial to the calculation of the head loss and is generally determined based on the geometric shape and size of the trough body. After the design flow rate, hydraulic gradient and wetted perimeter are determined, the cross-sectional area of the water flow can be calculated, specifically using the following formula:

[0086]

[0087] In formulas (1) and (2), V is the design flow velocity, n is the roughness coefficient, R is the hydraulic radius, S is the hydraulic slope, A is the cross-sectional area of the water flow, and p ... w is the wetted perimeter, i.e. the length of the portion where the water flow contacts the solid boundary.

[0088] The depth-to-width ratio and clearance of the trough section not only affect the structural stability of the trough but also the smoothness of water flow. The depth-to-width ratio is typically determined based on optimal hydraulic cross-sectional conditions and structural load requirements, while clearance ensures sufficient space for water flow to avoid safety issues caused by excessively high water levels.

[0089] After determining the dimensions of the water-passing section, the next step is to verify head loss. Head loss refers to the energy lost by water flowing through the aqueduct due to factors such as friction. It directly affects the efficiency and energy consumption of the water supply system. If the calculated head loss meets the design criteria, the previously determined hydraulic gradient, depth-to-width ratio, and clearance can be used as the final design values. However, if the design criteria are not met, the relevant parameters must be readjusted and the hydraulic design repeated until the optimal solution is found.

[0090] Through the above hydraulic design steps, it can be ensured that the water flow is smooth and the water delivery is efficient during the operation of the aqueduct. At the same time, it can also effectively reduce energy loss and improve the economy and reliability of the entire water delivery system.

[0091] S3. Structural design: Draft the cross-sectional dimensions of the steel structure aqueduct, and determine the bending capacity, design load, and design bending moment of the steel structure based on the cross-sectional dimensions; determine the recommended span of the structure based on the design bending moment and the bending capacity of the steel structure; check whether the draft cross-sectional dimensions of the steel structure aqueduct meet the construction space requirements and structural requirements. If not, repeat the structural design steps.

[0092] In the embodiments of this application, the core task of structural design is to rationally determine the cross-sectional dimensions and structural parameters of the steel aqueduct based on the results of the hydraulic design, ensuring that the aqueduct possesses sufficient structural strength and stability while meeting its intended function. The cross-sectional dimensions of the steel aqueduct require comprehensive consideration of the water-passing cross-sectional dimensions, water flow rate, water velocity, and the mechanical properties of the structure, as determined in the hydraulic design. The cross-sectional dimensions must not only meet hydraulic requirements but also consider the structure's bending capacity and construction feasibility. Typically, the cross-sectional shape can be rectangular, U-shaped, or other suitable shapes, with the specific dimensions optimized based on actual needs. Based on the proposed cross-sectional dimensions, the steel structure's bending capacity, design load, and design bending moment are calculated. Bending capacity is the maximum bending moment a structure can withstand and is directly related to the aqueduct's safety and reliability. Design loads include deadweight, water load, wind load, and crowd load. These loads generate various forces during aqueduct operation, requiring precise calculation to determine their magnitude and distribution. The design bending moment is calculated based on these loads and reflects the stresses the structure will experience under the most unfavorable operating conditions. The determination of span requires comprehensive consideration of the mechanical properties of the structure, construction conditions, and economic efficiency. Generally speaking, a larger span can reduce the number of piers and lower the project cost, but it will also increase the stress on the structure and the difficulty of construction. Therefore, it is necessary to find a span that meets the requirements of use while ensuring structural safety and economic rationality through reasonable design and calculation. The recommended span of the structure can be calculated and determined using the following formula:

[0093] M x =γ x Wf(3)

[0094] q=γ1q1+γ2q2+γ3q3(4)

[0095]

[0096] In formulas (3), (4), and (5), M x is the bending bearing capacity, W is the gross section modulus of the component, f is the design strength of the steel, γ x is the plastic development coefficient of the aqueduct section, q is the design load, q1 is the deadweight of the steel structure, q2 is the weight of water, q2 = Aρ, where ρ is the density of water, A is the volume of water, q3 is the maintenance crowd load, γ0 is the structural importance coefficient, γ1 is the structural deadweight partial coefficient, γ2 is the structural water load partial coefficient, γ3 is the structural crowd load partial coefficient, l0 is the structural calculation span, and M is the design bending moment;

[0097] Let M≤M x The preliminary cross-sectional dimensions and the recommended span of the structure that meets the cross-sectional conditions can be solved.

[0098] The proposed steel aqueduct cross-sectional dimensions are verified to ensure they meet construction space and structural requirements. Construction space requirements include the space required for operations such as hoisting and welding to ensure smooth construction. Structural requirements address aspects such as strength, stability, and durability to ensure the aqueduct's safe and reliable operation over the long term. If the verification results indicate that the proposed cross-sectional dimensions do not meet the requirements, the cross-sectional dimensions or structural parameters must be readjusted and the structural design re-performed until an optimal solution is found that meets all requirements.

[0099] S4. According to the cross-sectional dimensions of the steel structure aqueduct, stiffening ribs and diaphragms are set for the steel structure.

[0100] In the embodiment of the present application, the provision of stiffening ribs and diaphragms is crucial to improving the overall stability and local bearing capacity of the aqueduct, and can effectively enhance the bending and torsional properties of the structure, ensuring the safety and reliability of the aqueduct in long-term operation. Stiffening ribs are commonly used reinforcing members in steel structures, used to improve the local stability and bearing capacity of the structure. In steel structure aqueducts, stiffening ribs are usually arranged on the bottom plate and side plates of the trough body to prevent local instability under the action of water pressure and deadweight. The determination of the stiffening rib spacing should be based on the local stability analysis of the structure. Too large a spacing will cause local plate instability, while too small a spacing will increase material consumption, which is uneconomical. In general, the spacing of stiffening ribs can be calculated by a formula to ensure that the aspect ratio of the local plate is within the allowable range. The size of the stiffening ribs includes the height and thickness of the stiffening ribs. The height should be sufficient to provide sufficient rigidity to prevent local plates from buckling when subjected to stress. The thickness needs to be calculated based on the actual stress conditions to ensure that the stiffener itself has sufficient strength. In the actual design process, the stiffeners include longitudinal stiffeners and transverse stiffeners. The longitudinal stiffeners and transverse stiffeners must also meet the width-to-thickness ratio: Among them, h s is the width of the longitudinal stiffener or transverse stiffener, t s is the thickness of the longitudinal stiffener or transverse stiffener, f y The yield strength of steel. Common types of stiffeners are transverse and longitudinal. Transverse stiffeners primarily prevent plate buckling under transverse loads, while longitudinal stiffeners enhance the longitudinal rigidity of the structure. In aqueduct design, the appropriate stiffener type is typically selected based on the specific load conditions and structural form.

[0101] Diaphragms are important components in steel aqueducts, used to enhance the overall stability and lateral rigidity of the structure. The spacing of the diaphragms should be determined based on the stress conditions of the structure and the overall stability requirements. Excessively large spacing will affect the overall stability of the structure, while too small a spacing will increase material consumption. Generally, the spacing of the diaphragms can be optimized using structural analysis software. The dimensions of the diaphragms include their thickness and height. The thickness should be sufficient to provide sufficient strength and rigidity to prevent buckling when subjected to stress. The height needs to be calculated based on the overall stress conditions of the structure to ensure that the diaphragms can effectively transmit lateral forces. The connection method between the diaphragms and the trough body needs to ensure the reliability and strength of the connection. Welding or high-strength bolts are usually used. The connection design should comply with relevant specifications to ensure that it will not loosen or damage during long-term operation.

[0102] S5. Structural verification: Verify the principal stress strength of the steel structure aqueduct; verify the overall stability and local stability of the steel structure separately, among which the local stability verification includes the stiffening rib stiffness verification, stiffening rib arrangement spacing verification, stiffening rib inertia moment verification and diaphragm bearing strength verification; and perform anti-overturning verification on the trough body.

[0103] In the embodiment of the present application, the purpose of the principal stress strength calculation of the steel structure aqueduct is to ensure that the structure will not be damaged under the maximum stress state. This step requires calculating the maximum principal stress in the structure based on the design load and the geometric shape of the structure, and comparing it with the allowable stress of the material. If the maximum principal stress exceeds the allowable stress, the structure needs to be adjusted, such as increasing the material thickness or changing the structural form. The principal stress strength of the steel structure aqueduct is calculated using the following formula:

[0104]

[0105] γ0τ≤f vd (7)

[0106]

[0107] In formulas (6), (7), and (8), γ0 is the structural importance coefficient, σ x is the design value of normal stress, M y is the design value of the bending moment, W y,eff Effective section modulus, f d The design value of flexural strength, τ is the design value of shear stress, f vd is the design value of shear strength.

[0108] The purpose of the overall stability check is to ensure that the structure will not become unstable when subjected to external loads. This step needs to consider the geometry, material properties and load distribution of the structure, and to determine whether the structure has sufficient stability by calculating the critical load of the structure. If the critical load is less than the actual load, the structure needs to be strengthened, such as adding supports or changing the structural form. Before performing the overall stability check of the steel structure, first determine the conditions: Among them, h is the height of the tank body, f y is the yield strength of steel, b0 is the center distance of the web, and L1 is the lateral support spacing of the compression flange; whether it is satisfied, if it is satisfied, there is no need to perform the overall stability verification of the steel structure; if not, the following formula is used to perform the overall stability verification of the steel structure:

[0109]

[0110] M Rd,y =W y,eff f d (11)

[0111] M Rd,z =W z,eff f d (12)

[0112]

[0113] In formulas (9), (10), (11), (12), and (13), γ0 is the structural importance coefficient, which is 1.1, and M y 、M z is the maximum bending moment of the member around the y-axis and the z-axis, β m,y , β m,z is the corresponding bending moment M y 、M z The equivalent bending moment coefficient, is the relative slenderness ratio of the member around the y-axis and the z-axis, X LT,z 、X LT,y M z and M y The overall stability reduction factor of the bending-torsional instability mode of the component around the y-axis and the z-axis under the action of the bending moment in the action plane alone, W y,eff 、W z,eff is the effective section modulus of the component around the y-axis and z-axis, M cr,y 、M cr,z M y and M z The overall flexural-torsional elastic buckling moment of the component about the y-axis and z-axis considering the influence of constraints under the action of the bending moment in the action plane alone, M Rd,y 、M Rd,zis the cross-sectional bending capacity of the member around the y-axis and the z-axis considering local buckling, f d is the design value of bending strength, f y is the yield strength of steel. The purpose of local stability verification is to ensure that local components of the structure will not be locally unstable when subjected to external loads. This step requires detailed analysis and verification of local components such as stiffeners and diaphragms. The stiffener stiffness verification can ensure that the stiffeners have sufficient stiffness to effectively resist the buckling of local plates; the stiffener arrangement spacing verification can ensure that the stiffener arrangement spacing is reasonable and can effectively improve the stability of local plates; the stiffener inertia moment verification can ensure that the stiffener moment of inertia is large enough to effectively resist the bending of local plates; the diaphragm compressive strength verification can ensure that the diaphragm has sufficient compressive strength to effectively resist lateral loads; the trough body anti-overturning verification can ensure that the trough body has sufficient anti-overturning capacity to effectively resist external loads such as wind loads.

[0114] The stiffness of the compression stiffener is calculated using the following formula:

[0115]

[0116] n=n l +1 (19)

[0117] In formulas (14), (15), (16), (17), (18), and (19), γ l is the relative stiffness of the longitudinal stiffener, Among them, I l is the bending inertia moment of a single longitudinal stiffener about the main axis of the stiffener plate, b is the calculated width of the longitudinal stiffener plate / transverse stiffener plate, and E is the elastic modulus of the steel;

[0118] γ t is the relative stiffness of the transverse stiffener, Among them, I t is the bending inertia moment of a single transverse stiffener about the main axis of the stiffener plate, a is the calculated length of the longitudinal stiffener plate / transverse stiffener plate;

[0119] t is the thickness of the motherboard, a t is the transverse stiffener spacing, α is the aspect ratio of the longitudinal stiffener plate / transverse stiffener plate;

[0120] δ l is the ratio of the cross-sectional area of a single longitudinal stiffener to the area of the base plate, Among them, A s,l is the cross-sectional area of a single longitudinal stiffener;

[0121] D is the width of the one-way slab, Among them, υ is Poisson's ratio, which is 0.3;

[0122] n l The number of longitudinal stiffeners is arranged at equal intervals.

[0123] The stiffening rib spacing verification includes the top plate compression stiffening rib spacing verification, the bottom plate tension stiffening rib spacing verification, and the transverse stiffening rib spacing verification;

[0124] The following formula is used to calculate the spacing of the top plate compression stiffeners:

[0125] l l ≤40t f (20)

[0126] In formula (20), l l is the stiffener spacing, t f is the flange thickness;

[0127] The spacing of the tensile stiffeners in the bottom plate is calculated using the following formula:

[0128] a≤80t f (twenty one)

[0129] In formula (21), a is the spacing between stiffeners, t f is the flange thickness;

[0130] The following formula is used to check the spacing of transverse stiffeners:

[0131] a≤1.5h w (twenty two)

[0132] In formula (22), h w is the net height of the web, and a is the spacing between stiffeners.

[0133] The moment of inertia calculation of stiffeners includes the moment of inertia calculation of transverse stiffeners and the moment of inertia calculation of longitudinal stiffeners of webs;

[0134] The moment of inertia of the transverse stiffener is calculated using the following formula:

[0135]

[0136] In formula (23), t w is the web thickness, h w is the net height of the web, I t is the moment of inertia of the transverse stiffener;

[0137] The moment of inertia of the longitudinal stiffener of the web is calculated using the following formula:

[0138]

[0139] In formula (24), t wis the web thickness, I l Moment of inertia of the longitudinal web stiffener, h w is the net height of the web, Where a is the spacing between the transverse stiffeners of the web.

[0140] The spacing between diaphragms is not more than 3m. The diaphragms are equipped with supporting stiffeners. The compressive strength of the diaphragms is calculated using the following formula:

[0141]

[0142] In formulas (25) and (26), γ0 is the structural importance coefficient, which is 1.1, and R V is the support reaction, A S is the sum of the supporting stiffener areas, B eb is the effective calculation width of the web under local pressure, t w is the web thickness, f cd is the design value of steel compressive strength, B ev is the effective width of the web, f d is the design value of steel strength.

[0143] The anti-overturning calculation of the trough body adopts the following formula:

[0144]

[0145] In formula (27), k qf is the lateral anti-overturning stability coefficient, take k qf =2.5,∑S bk,i The design value of the effect of the basic combination of actions (the partial coefficient is 1) to stabilize the superstructure, ∑S sk,i The design value of the effect of the basic combination of actions (partial coefficient is 1) that causes the superstructure to become unstable.

[0146] S6. After all calculations meet the specifications, the aqueduct body shall be designed for corrosion protection and water stopping.

[0147] The anti-corrosion design adopts a bottom-to-top coating, and the coating adopts super wear-resistant epoxy paint, 3 coats, 900um.

[0148] In summary, the design method of a simply supported steel structure aqueduct provided by this application is that a simply supported steel structure aqueduct usually needs to span a larger space, such as a valley or a river, which makes the structure susceptible to various external forces during operation, such as wind loads, water flow impact, etc. The design of stiffening ribs and diaphragms can significantly enhance the overall stability and local stability of the structure. Stiffening ribs effectively prevent the instability of local plates under water pressure and deadweight by improving the stiffness and buckling resistance of local plates. Diaphragms improve the stability of the structure under lateral loads by enhancing the lateral stiffness of the structure, thereby ensuring the safety and reliability of the aqueduct in long-term operation; through the detailed design of stiffening ribs and diaphragms, this application not only improves the stability and bearing capacity of the structure, but also optimizes the mechanical properties of the structure. For example, the reasonable arrangement of the spacing and size of the stiffening ribs can reduce the amount of material used and reduce the deadweight of the structure while ensuring the strength of the structure, thereby improving the economy of the structure. A well-designed diaphragm effectively transmits lateral forces, reduces lateral deformation, and further optimizes the mechanical properties of the structure. In actual construction, a well-designed stiffener and diaphragm design can improve construction feasibility and efficiency. The layout of stiffeners and diaphragms should be as regular as possible to facilitate construction operations and quality control. Through detailed design and verification, this application ensures smooth construction of stiffeners and diaphragms, reduces construction difficulty and cost, and improves construction efficiency. Simply supported steel aqueducts are exposed to humid environments for long periods of time and are susceptible to corrosion and leakage. This application significantly improves the durability and service life of the aqueduct through anti-corrosion and water-stopping designs. The design of stiffeners and diaphragms not only enhances structural stability but also provides a physical foundation for anti-corrosion and water-stopping designs. For example, a well-designed stiffener and diaphragm layout can reduce cracks and leakage points in the structure, thereby reducing the risk of corrosion. The design of a simply supported steel aqueduct requires comprehensive consideration of multiple factors, such as construction conditions, water head loss, and topographic and geological conditions. Through the detailed design of stiffeners and diaphragms, this application can adapt to various complex engineering scenarios. For example, in areas with poor geological conditions, reasonable stiffener and diaphragm design can enhance the structure's ability to resist deformation and ensure the stability of the structure. In areas with large wind loads, the design of stiffeners and diaphragms can improve the structure's ability to resist wind and ensure the safety of the structure. This application fills this gap by providing a complete set of design processes and calculation methods, providing theoretical support and practical guidance for the design and construction of steel structure aqueducts. This detailed design and verification method not only improves the scientificity and rationality of the design, but also provides engineering and technical personnel with a clear design basis. This application also covers the entire life cycle design process from engineering planning, hydraulic design to structural verification. In the hydraulic design, the hydraulic performance of the aqueduct is ensured to meet the design standards by formulating the design flow rate, hydraulic gradient and wetted perimeter and calculating the water-passing cross-sectional area.During structural design, the steel structure's bending capacity, design load, and design bending moment were rationally determined to ensure its safety and reliability under various operating conditions. During structural verification, comprehensive principal stress strength, overall stability, and local stability calculations further ensured structural safety and reliability. This not only ensured structural safety and reliability, but also improved the project's economic and practicality.

[0149] The above is an explanation of the implementation mode of the present application by specific specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Although the description of the present application will be introduced in conjunction with some embodiments, this does not mean that the features of this application are limited to the implementation mode. On the contrary, the purpose of introducing the application in conjunction with the implementation mode is to cover other options or modifications that may be extended based on the claims of the present application. In order to provide an in-depth understanding of the present application, the above description contains many specific details. The present application can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present application, some specific details will be omitted in the description. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other unless there is a conflict.

[0150] It should be noted that in this specification, similar numbers and letters represent similar items in the above figures. Therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures. In the description of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the figures. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they should not be understood as limiting this application. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance. In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "mounted", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or it can be a communication between two elements. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0151] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A design method for a simply supported steel structure aqueduct, characterized in that: Includes the following: Determine the engineering grade and scale of the aqueduct based on planning conditions and functional requirements; Hydraulic design: Develop the design flow rate, hydraulic gradient, and wetted perimeter. Calculate the cross-sectional area of the flume body based on the design flow rate, hydraulic gradient, and wetted perimeter. Develop the depth-to-width ratio and clearance of the flume body section to determine the dimensions of the cross-sectional area. Verify that the head loss meets the design standards. If so, set the hydraulic gradient, depth-to-width ratio, and clearance to the corresponding design values. Otherwise, repeat the hydraulic design steps. Structural design: Draft the cross-sectional dimensions of the steel structure aqueduct, and determine the steel structure's bending capacity, design load, and design bending moment based on the cross-sectional dimensions. Determine the recommended span of the structure based on the design bending moment and the steel structure's bending capacity. Verify that the proposed cross-sectional dimensions of the steel structure aqueduct meet construction space and structural requirements. If not, repeat the structural design steps. According to the cross-sectional dimensions of the steel structure aqueduct, stiffening ribs and diaphragms are provided for the steel structure; Structural verification: Verify the principal stress strength of the steel aqueduct; verify the overall stability and local stability of the steel structure. The local stability verification includes the stiffening rib stiffness verification, stiffening rib spacing verification, stiffening rib moment of inertia verification, and diaphragm bearing strength verification; and perform anti-overturning verification on the aqueduct body. After all calculations meet the specifications, the aqueduct body will be designed for corrosion protection and water stopping.

2. The design method of a simply supported steel structure aqueduct according to claim 1, characterized in that: In water conservancy design, the calculation formula for the water-passing section is as follows: In formulas (1) and (2), V is the design flow velocity, n is the roughness coefficient, R is the hydraulic radius, S is the hydraulic slope, A is the cross-sectional area of the water flow, and p ... w is the wetted perimeter, i.e. the length of the portion where the water flow contacts the solid boundary.

3. The design method of a simply supported steel structure aqueduct according to claim 1, characterized in that: The recommended span of the structure is determined by the following formula: M x =c x Wf (3) q=γ1q1+γ2q2+γ3q3 (4) In formulas (3), (4), and (5), M x is the bending bearing capacity, W is the gross section modulus of the component, f is the design strength of the steel, γ x is the plastic development coefficient of the aqueduct section, q is the design load, q1 is the deadweight of the steel structure, q2 is the weight of water, q2 = Aρ, where ρ is the density of water, A is the volume of water, q3 is the maintenance crowd load, γ0 is the structural importance coefficient, γ1 is the structural deadweight partial coefficient, γ2 is the structural water load partial coefficient, γ3 is the structural crowd load partial coefficient, l0 is the structural calculation span, and M is the design bending moment; Let M≤M x The preliminary cross-sectional dimensions and the recommended span of the structure that meets the cross-sectional conditions can be solved.

4. The design method of a simply supported steel structure aqueduct according to claim 1, characterized in that: The principal stress strength of the steel structure aqueduct is calculated using the following formula: h0τ≤f vd (7) In formulas (6), (7), and (8), γ0 is the structural importance coefficient, σ x is the design value of normal stress, M y Design value of bending moment, W y,eff is the effective section modulus, f d The design value of flexural strength, τ is the design value of shear stress, f vd is the design value of shear strength.

5. The design method of a simply supported steel structure aqueduct according to claim 1, characterized in that: If the conditions are met: Among them, h is the height of the tank body, f y is the yield strength of steel, b0 is the center distance of web, L1 is the lateral support spacing of compression flange; There is no need to verify the overall stability of the steel structure.

6. The design method of a simply supported steel structure aqueduct according to claim 1, characterized in that: The overall stability is verified using the following formula: M Rd,y =W y,eff f d (11) M Rd,z =W z,eff f d (12) In formulas (9), (10), (11), (12), and (13), γ0 is the structural importance coefficient, which is 1.1, and M y 、M z is the maximum bending moment of the member around the y-axis and the z-axis, β m,y , β m,z is the corresponding bending moment M y 、M z The equivalent bending moment coefficient, is the relative slenderness ratio of the member around the y-axis and the z-axis, LT,z , χ LT,y M z and M y The overall stability reduction factor of the bending-torsional instability mode of the component around the y-axis and the z-axis under the action of the bending moment in the action plane alone, W y,eff 、W z,eff is the effective section modulus of the component around the y-axis and z-axis, M cr,y 、M cr,z M y and M z The overall flexural-torsional elastic buckling moment of the component about the y-axis and z-axis considering the influence of constraints under the action of the bending moment in the action plane alone, M Rd,y 、M Rd,z is the cross-sectional bending capacity of the member around the y-axis and the z-axis considering local buckling, f d is the design value of bending strength, f y is the yield strength of steel.

7. The design method of a simply supported steel structure aqueduct according to claim 1, characterized in that: The stiffening ribs include longitudinal stiffening ribs and transverse stiffening ribs, and the longitudinal stiffening ribs and transverse stiffening ribs satisfy the width-to-thickness ratio: Among them, h s is the width of the longitudinal stiffener or transverse stiffener, t s is the thickness of the longitudinal stiffener or transverse stiffener, f y is the yield strength of steel.

8. The design method of a simply supported steel structure aqueduct according to claim 7, characterized in that: The stiffness of the compression stiffener is calculated using the following formula: In formulas (14), (15), (16), (17), (18), and (19), γ l is the relative stiffness of the longitudinal stiffener, Among them, I l is the bending inertia moment of a single longitudinal stiffener about the main axis of the stiffener plate, b is the calculated width of the longitudinal stiffener plate / transverse stiffener plate, and E is the elastic modulus of the steel; γ t is the relative stiffness of the transverse stiffener, Among them, I t is the bending inertia moment of a single transverse stiffener about the main axis of the stiffener plate, a is the calculated length of the longitudinal stiffener plate / transverse stiffener plate; t is the thickness of the motherboard, a t is the transverse stiffener spacing, α is the aspect ratio of the longitudinal stiffener plate / transverse stiffener plate; δ l is the ratio of the cross-sectional area of a single longitudinal stiffener to the area of the base plate, Among them, A s,l is the cross-sectional area of a single longitudinal stiffener; D is the width of the one-way slab, Among them, υ is Poisson's ratio, which is 0.3; n l The number of longitudinal stiffeners is arranged at equal intervals.

9. The design method of a simply supported steel structure aqueduct according to claim 7, characterized in that: The stiffening rib spacing verification includes the top plate compression stiffening rib spacing verification, the bottom plate tension stiffening rib spacing verification, and the transverse stiffening rib spacing verification; The following formula is used to calculate the spacing of the top plate compression stiffeners: l l ≤40t f (20) In formula (20), l l is the stiffener spacing, t f is the flange thickness; The spacing of the tensile stiffeners in the bottom plate is calculated using the following formula: a≤80t f (21) In formula (21), a is the spacing between stiffeners, t f is the flange thickness; The following formula is used to check the spacing of transverse stiffeners: <h2 style=";text-align:left;direction:ltr">a≤1.5h<h2 style=";text-align:left;direction:ltr"> w <h2 style=";text-align:left;direction:ltr"> (22) In formula (22), h w is the net height of the web, and a is the spacing between stiffeners.

10. The design method of a simply supported steel structure aqueduct according to claim 7, characterized in that: The moment of inertia calculation of stiffeners includes the moment of inertia calculation of transverse stiffeners and the moment of inertia calculation of longitudinal stiffeners of webs; The moment of inertia of the transverse stiffener is calculated using the following formula: In formula (23), t w is the web thickness, h w is the net height of the web, I t is the moment of inertia of the transverse stiffener; The moment of inertia of the longitudinal stiffener of the web is calculated using the following formula: In formula (24), t w is the web thickness, I l Moment of inertia of the longitudinal web stiffener, h w is the net height of the web, Where a is the spacing between the transverse stiffeners of the web.

11. The design method of a simply supported steel structure aqueduct according to claim 1, characterized in that: The spacing between diaphragms is not more than 3m. The diaphragms are equipped with supporting stiffeners. The compressive strength of the diaphragms is calculated using the following formula: In formulas (25) and (26), γ0 is the structural importance coefficient, which is 1.1, and R V is the support reaction, A S is the sum of the supporting stiffener areas, B eb is the effective calculation width of the web under local pressure, t w is the web thickness, f cd is the design value of steel compressive strength, B ev is the effective width of the web, f d is the design value of steel strength.

12. The design method of a simply supported steel structure aqueduct according to claim 1, characterized in that: The anti-overturning calculation of the trough body adopts the following formula: In formula (27), k qf is the lateral anti-overturning stability coefficient, take k qf =2.5,∑S bk,i The design value of the effect of the basic combination of actions (the partial coefficient is 1) to stabilize the superstructure, ∑S sk,i The design value of the effect of the basic combination of actions (partial coefficient is 1) that causes the superstructure to become unstable.

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