Structure for improving anti-collision performance of bridge in longitudinal bridge direction

Abstract

The invention discloses a structure for improving the anti-collision performance of a bridge in the longitudinal bridge direction, which is mainly characterized in that inhaul cables are arranged on the two sides of the tops of adjacent bridge piers, a plurality of bridge piers are connected together through the inhaul cables, and when the bridge piers are collided, the inhaul cables and the bridge piers are stressed together to form a combined stress system. The inhaul cables on the two sides of the tops of the adjacent bridge piers are symmetrically arranged or arranged in a crossed mode. The inhaul cables are arranged between the adjacent bridge piers, transmission and dispersion of impact force between the adjacent bridge piers are achieved through the inhaul cables, pier top displacement of the bridge piers under longitudinal bridge direction ship impact is reduced, and beam falling is avoided; and based on a static stiffness distribution method and a force method of a spring, the cross section area of the inhaul cable between the piers is optimized, the longitudinal anti-collision performance of the bridge is improved, and the problems that in the prior art, the anti-collision performance is insufficient, and economical efficiency is poor are solved.

Description

Technical Field

[0001] This invention belongs to the field of bridge engineering technology, and specifically relates to a structure for improving the longitudinal collision resistance of bridges. Background Technology

[0002] Beam bridges are a commonly used type of bridge in bridge engineering, with a long history of development. Due to their ease of manufacture and erection, and wide applicability, they constitute a large proportion of bridge construction, especially playing a vital role in transportation in western my country. As important transportation hubs, the safety of bridges is crucial to economic development and social operation.

[0003] However, bridges are susceptible to various hazards during their design and operation, with ship collisions being one of the most common. Ship-bridge collisions are also a leading cause of bridge failure. Statistics from the European Maritime Safety Authority (EMSA) and the Transport Safety Board of Canada (TSB) indicate that collisions and contact are among the most common types of maritime accidents resulting in personal injury. Bridges located in navigable waterways are man-made obstacles for vessels, posing a risk of collision. In the event of a ship-bridge collision, the bridge structure may be subjected to enormous lateral impact loads, leading to severe damage or even complete collapse, resulting in significant economic losses, personal injury, and negative social impacts.

[0004] Bridge collision avoidance design mainly includes three aspects: bridge collision risk assessment, bridge collision response analysis methods, and bridge collision avoidance measures and design. There is more research on the first two aspects, but less research on bridge collision avoidance measures. The "Specifications for Collision Resistance Design of Highway Bridges" broadly classifies bridge collision avoidance measures into two types: active collision avoidance measures and passive collision avoidance measures. Traditional active bridge collision avoidance generally uses Vessel Traffic Management Systems (VTS) and Automatic Identification Systems (AIS) to establish bridge collision warnings to guide vessel navigation, and uses video surveillance systems (CCTV) to monitor the situation in the bridge area. The aim is to improve the safety and efficiency of bridges and water traffic. Through data integration and decision support systems, it effectively reduces collision risks and ensures the safe operation of vessel traffic. However, VTS and AIS require the installation of a large amount of expensive equipment, resulting in high costs, while traditional CCTV cannot achieve active warning functions.

[0005] Passive collision avoidance systems are facilities designed to reduce impact force and mitigate damage when a ship has already collided with or is about to collide with a bridge pier. They can be broadly categorized into direct and indirect structures based on whether the ship will actually impact the pier. The primary target of these systems is the bridge pier itself. As a critical component of the bridge structure, the pier not only bears the vertical and horizontal forces transmitted from the superstructure of adjacent spans, but also experiences wind forces. Piers located in rivers also bear the pressure of flowing water and the potential impact forces from ice-loaded vessels or drifting debris. The reliability of the piers plays a crucial role in the safe use of the entire bridge. When a ship collides with the superstructure of a bridge, the main beams and the lower part of the arches are typically impacted, while the bow, mast, deckhouse, and other hull structures usually collide with the ship, resulting in relatively smaller impact forces. However, when a ship directly contacts a bridge pier, a tremendous impact force is generated in a very short time. This impact force can cause structural damage to the impact area and even lead to the serious consequence of the pier collapsing. Although various passive collision avoidance facilities have been proposed and applied, their actual application effects are inconsistent due to significant differences in their structure, protection capabilities, maintenance requirements, economics, and impact on the waterway environment.

[0006] In conclusion, bridge structural damage caused by ship collisions is increasing, and the catastrophic consequences are undeniable. These accidents not only severely damage bridge structures but can also lead to enormous economic losses and social impacts. Over the past few decades, ship-bridge collisions have become a focal point of international academic and engineering concern, highlighting the growing urgency and importance of research in this area. Summary of the Invention

[0007] The purpose of this invention is to provide a structure that improves the longitudinal collision resistance of bridges. This invention achieves the transmission and dispersion of impact force between adjacent piers by installing cables between them, reducing the pier top displacement under longitudinal ship impact and preventing beam collapse. Furthermore, it optimizes the cable arrangement between piers based on the Lagrange function extremum method, thereby improving the longitudinal collision resistance of bridges and solving the problems of insufficient collision resistance and poor economy in existing technologies.

[0008] To achieve the objectives of this invention, the following technical solution is adopted:

[0009] A structure to improve the longitudinal impact resistance of bridges mainly involves installing cables on both sides of the top of adjacent piers. Multiple piers are connected together by the cables, and the cables and piers share the load, forming a joint load-bearing system. This reduces the stress on the impacted piers and improves the structural resistance.

[0010] The present invention further illustrates that the cables on both sides of the top of the adjacent bridge piers are arranged symmetrically or crosswise.

[0011] The present invention further illustrates that when the cables on both sides of the top of the adjacent bridge piers are arranged symmetrically, the cross-sectional area A of the cables is... S Determined by the following formula:

[0012]

[0013] In the formula, L is the bridge span, K S For the stiffness of the cable, E S The elastic modulus of the cable;

[0014] The stiffness K of the cable S The target displacement ΔU of the pier top displacement of the piers before and after the impact on the Gazelle piers satisfies the following formula:

[0015]

[0016] In the formula, ΔU represents the displacement reduction of the pier top before and after the impact, which is determined by the design target; K P K represents the longitudinal deformation stiffness of the bridge pier. eq1 The equivalent stiffness of the spring at the top of the impacted pier is obtained by the static stiffness distribution method based on the spring.

[0017] Furthermore, the equivalent stiffness K of the spring at the top of the impacted pier... eq1 Satisfy the following formula:

[0018] After n crosses the Caspian Sea, the structural mechanics diagram proposed in this invention is as follows: Figure 3 As shown, the equivalent spring stiffness at the top of piers n#, (n-1)#, ..., 1# after simplifying the spring is:

[0019]

[0020] The above formula is a progressive relationship.

[0021] Taking the three-transatlantic region as an example (n=3): K eq1 K represents the equivalent stiffness of the spring at the top of the impacted pier (the equivalent stiffness of the spring at the top of pier #1). eq2 K represents the equivalent stiffness of the adjacent piers to the impacted pier (the equivalent stiffness of the spring at the top of pier #2). eq3 The equivalent stiffness of the pier adjacent to the impacted pier (the equivalent stiffness of the spring at the top of pier #3), such as Figure 4 As shown.

[0022] The equivalent spring stiffness k at the top of the pier of the three-span cableway eq1 The solution process is as follows: Figure 5 As shown.

[0023] The stiffness of each spring is then:

[0024]

[0025] Finally, the equivalent stiffness K of the spring at the top of the impacted pier can be obtained. eq1 .

[0026] The present invention further illustrates that when the cables on both sides of the top of the adjacent bridge piers are arranged in a crisscross pattern, the cross-sectional area A of the cables is... S The displacement at the top of the pier is determined by the internal forces within the impacted bridge pier. The specific solution process is as follows:

[0027] First, we make the following assumptions:

[0028]

[0029] The process of substituting load displacement and constant displacement, and substituting parameters is shown in the table below:

[0030]

[0031] Note: Except for the constant and load variables mentioned in the above remarks, all others are 0.

[0032] Based on the above derivation of the calculation formulas for the internal forces and displacements of the impacted bridge pier structure, a solution calculation program was developed using Mathematic software. The program flow is as follows: Figure 6 As shown.

[0033] Following the above process, the internal forces and displacements of a structure with any number of intersecting cables can be determined. Taking a three-span cable system as an example, the specific solution process is as follows:

[0034] (1) Determine the degree of static indeterminacy of the structure and establish the force method equations. The three-span cable structure is of the third degree of static indeterminacy, therefore the force method equations are:

[0035]

[0036] (2) Substituting the load displacement and constant displacement, the force method equation after substitution is:

[0037]

[0038] (3) Depending on the actual engineering requirements, decide whether to consider the influence of the cap beam stiffness, and then solve for δ. A δ B δ 1P Substituting the numerical values ​​into the substituted force method equations and solving the force method equations yields the cable force values. The calculated cable forces are shown in the table below:

[0039]

[0040] (4) Based on the principle of virtual work, we can derive the cable force for each span from the previous step. Treating these cable forces as external loads acting on a single pier, we can calculate the internal forces and displacements of the structure based on the obtained cable forces. The calculation method is consistent with the single-span cable addition process described above.

[0041]

[0042] In the formula, U 1# Let T1 be the displacement of the pier top under impact, T1 be the cable force within one span, and E be the flexural stiffness of the pier. P I P The tensile stiffness of the cable is E S A S h is the pier height, L is the span, and F is the bridge pier height. X 'b' represents the impact force of the ship, and 'b' represents the distance from the point of impact to the bottom of the pier.

[0043] (5) The result obtained from the above formula includes A S Therefore, the required cable cross-sectional area can be obtained by inverse solution based on the required internal forces and displacements of the structure.

[0044] Advantages of this invention:

[0045] 1. Improved Impact Resistance: By connecting the piers with cables, the displacement and bending moment of the piers under ship impact can be effectively reduced, lowering the risk of pier collapse and improving the overall impact resistance of the bridge structure. Specifically, the pier top displacement is reduced by 30% to 40%, and the pier bottom bending moment is reduced by 20% to 30%, effectively preventing pier collapse.

[0046] 2. Simplified design and construction: Compared with traditional complex anti-collision facilities, the cable system of this invention is simple in design and easy to construct, reducing project costs and maintenance costs.

[0047] 3. High adaptability: It is suitable for small and medium span bridges as well as large span bridges, and can be widely used in the design of new bridges and the reinforcement of existing bridges.

[0048] 4. Economic efficiency: Compared with traditional anti-collision facilities, the cost is reduced by about 25%, and it does not require frequent maintenance. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of a symmetrically arranged cable structure in one embodiment of the present invention.

[0050] Figure 2 This is a schematic diagram of a cross-arranged cable structure in one embodiment of the present invention.

[0051] Figure 3 This is a structural mechanics diagram of an embodiment of the present invention with n-span symmetrically arranged cables.

[0052] Figure 4This is a schematic diagram of the equivalent spring stiffness at the pier top when the cables are arranged symmetrically across three spans in one embodiment of the present invention.

[0053] Figure 5 This is a flowchart illustrating the solution of the equivalent stiffness of the spring at the top of the impact pier when the cables are arranged symmetrically across three spans in one embodiment of the present invention.

[0054] Figure 6 This is a flowchart illustrating the calculation procedure for the internal forces and displacements of a bridge pier structure subjected to impact when cables are arranged in a cross pattern, according to one embodiment of the present invention. Detailed Implementation

[0055] The invention will be further described below with reference to the accompanying drawings.

[0056] Example 1:

[0057] A structure to improve the longitudinal impact resistance of bridges mainly involves installing cables on both sides of the top of adjacent piers. Multiple piers are connected together by the cables, and the cables and piers share the load, forming a joint load-bearing system. This reduces the stress on the impacted piers and improves the structural resistance.

[0058] To further explain, the cables on both sides of the top of the adjacent bridge piers are arranged symmetrically.

[0059] To further explain, the cross-sectional area A of the cable... S Determined by the following formula:

[0060]

[0061] In the formula, L is the bridge span, K S For the stiffness of the cable, E S The elastic modulus of the cable;

[0062] The stiffness K of the cable S The target displacement ΔU of the pier top displacement of the piers before and after the impact on the Gazelle piers satisfies the following formula:

[0063]

[0064] In the formula, ΔU represents the displacement reduction of the pier top before and after the impact, which is determined by the design target; K P K represents the longitudinal deformation stiffness of the bridge pier. eq1 The equivalent stiffness of the spring at the top of the impacted pier is obtained by the static stiffness distribution method based on the spring.

[0065] The steps for calculating the displacement ΔU of the pier top of the impacted pier before and after the collision are as follows:

[0066] Given that the stiffness of the cable is set to K S =E S A S / L, the longitudinal deformation stiffness of the bridge pier is K P =3E P I P / h 3 After spanning n spans, the equivalent spring stiffness at the top of piers n#, (n-1)#, ..., 1# after simplifying the springs is: The equivalent stiffness K of the spring on the top of the impact pier. eq1 for:

[0067] Therefore, the cable force T1 within a span can be obtained by the method of this patent as follows:

[0068]

[0069] In the formula, the bending stiffness of the bridge pier is E. P I P The tensile stiffness of the cable is E S A S The pier height is h, the span is L, and the ship impact force is F. X K eq1 The equivalent stiffness of the spring at the top of the impact pier.

[0070] Then the displacement U of the top of the impacted pier after the cable is added 1# for:

[0071]

[0072] In the formula, the bending stiffness of the bridge pier is E. P I P The tensile stiffness of the cable is E S A S The distance from the point of impact to the bottom of the pier is b, the pier height is h, the span is L, and the impact force is F. X K eq1 The equivalent stiffness of the spring at the top of the impact pier.

[0073] The displacement of the pier base before the cable was added is known. The displacement decrease of the pier top of the impacted pier before and after the impact is ΔU:

[0074]

[0075] Furthermore, the equivalent stiffness K of the spring at the top of the impacted pier... eq1 Satisfy the following formula:

[0076] After n crosses the Caspian Sea, the structural mechanics diagram proposed in this invention is as follows: Figure 3 As shown, the equivalent spring stiffness at the top of piers n#, (n-1)#, ..., 1# after simplifying the spring is:

[0077]

[0078] The above formula is a progressive relationship.

[0079] Taking the three-transatlantic region as an example (n=3): K eq1 K represents the equivalent stiffness of the spring at the top of the impacted pier (the equivalent stiffness of the spring at the top of pier #1). eq2 K represents the equivalent stiffness of the adjacent piers to the impacted pier (the equivalent stiffness of the spring at the top of pier #2). eq3 The equivalent stiffness of the pier adjacent to the impacted pier (the equivalent stiffness of the spring at the top of pier #3), such as Figure 4 As shown.

[0080] The equivalent spring stiffness k at the top of the pier of the three-span cableway eq1 The solution process is as follows: Figure 5 As shown.

[0081] The stiffness of each spring is then:

[0082]

[0083] Finally, the equivalent stiffness K of the spring at the top of the impacted pier can be obtained. eq1 .

[0084] Taking the cable-pier structure formed after adding cables to one span of a beam bridge as an example, the equivalent spring stiffness of the pier top of the impact pier when adding cables to one span is: Based on the target displacement reduction ΔU of the pier tops before and after the impact, the value of ΔU can be determined, and the spring stiffness can then be solved in reverse. The required cable cross-sectional area is then calculated based on the cable stiffness; the same logic applies to the remaining spans.

[0085] Example 2:

[0086] A structure to improve the longitudinal impact resistance of bridges mainly involves installing cables on both sides of the top of adjacent piers. Multiple piers are connected together by the cables, and the cables and piers share the load, forming a joint load-bearing system. This reduces the stress on the impacted piers and improves the structural resistance.

[0087] To further explain, the cables on both sides of the top of the adjacent bridge piers are arranged in a crisscross pattern.

[0088] To further explain, the cross-sectional area A of the cable... S The displacement at the top of the pier is determined by the internal forces within the impacted bridge pier. The specific solution process is as follows:

[0089] First, we make the following assumptions:

[0090]

[0091] The process of substituting load displacement and constant displacement, and substituting parameters is shown in the table below:

[0092]

[0093] Note: Except for the constant and load variables mentioned in the above remarks, all others are 0.

[0094] Based on the above derivation of the calculation formulas for the internal forces and displacements of the impacted bridge pier structure, a solution calculation program was developed using Mathematic software. The program flow is as follows: Figure 6 As shown.

[0095] Following the above process, the internal forces and displacements of a structure with any number of intersecting cables can be determined. Taking a three-span cable system as an example, the specific solution process is as follows:

[0096] (1) Determine the degree of static indeterminacy of the structure and establish the force method equations. The three-span cable structure is of the third degree of static indeterminacy, therefore the force method equations are:

[0097]

[0098] (2) Substituting the load displacement and constant displacement, the force method equation after substitution is:

[0099]

[0100] (3) Depending on the actual engineering requirements, decide whether to consider the influence of the cap beam stiffness, and then solve for δ. A δ B δ 1P Substituting the numerical values ​​into the substituted force method equations and solving the force method equations yields the cable force values. The calculated cable forces are shown in the table below:

[0101]

[0102]

[0103] (4) Based on the principle of virtual work, we can derive the cable force for each span from the previous step. Treating these cable forces as external loads acting on a single pier, we can calculate the internal forces and displacements of the structure based on the obtained cable forces. The calculation method is consistent with the single-span cable addition process described above.

[0104]

[0105] In the formula, U 1# Let T1 be the displacement of the pier top under impact, T1 be the cable force within one span, and E be the flexural stiffness of the pier. P I P The tensile stiffness of the cable is E S A S h is the pier height, L is the span, and F is the bridge pier height. X'b' represents the impact force of the ship, and 'b' represents the distance from the point of impact to the bottom of the pier.

[0106] (5) The result obtained from the above formula includes A S Therefore, the required cable cross-sectional area can be obtained by inverse solution based on the required internal forces and displacements of the structure.

[0107] Obviously, the above embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description; it is neither necessary nor possible to exhaustively list all possible implementations; however, obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

[0108] Taking a beam bridge as an example, the bridge span is L = 40m, the pier height is h = 25m, the pier cross-section is a solid rectangle with dimensions b × h = 5m × 2m, and the pier type is a single-column pier. Assume that pier #1 is struck by a ship with an impact force F. X =5000kN, impact point distance from pier bottom b = 0.7hm. To improve the pier's resistance to ship collision and reduce the pier top displacement, pier bottom bending moment, and impact point bending moment of the impacted pier, a symmetrically arranged cable-pier joint structure is adopted. Then, based on the different displacement reduction targets ΔU of the impacted pier, the L, h, and E of this beam bridge will be... P E S Substituting the values, we get the minimum required Calais logarithm, rounded up to the nearest integer:

[0109]

[0110] According to the table above, if the target displacement reduction ΔU is 30%, the number of cable pairs required for the first, second, and third spans is 11, 9, and 9, respectively; if the target displacement reduction ΔU is 40%, the number of cable pairs required for the first, second, and third spans is 29, 17, and 16, respectively.

Claims

1. A structure for improving the longitudinal collision resistance of bridges, characterized in that: Cables are installed on both sides of the top of adjacent piers to connect multiple piers together. The cables and piers share the load, forming a joint load-bearing system.

2. The structure for improving the longitudinal collision resistance of bridges according to claim 1, characterized in that: The cables on both sides of the top of the adjacent piers are arranged symmetrically or crosswise.

3. The structure for improving the longitudinal collision resistance of bridges according to claim 2, characterized in that: When the cables on both sides of the top of the adjacent piers are arranged symmetrically, the cross-sectional area A of the cables is... S Determined by the following formula: In the formula, L is the bridge span, K S For the stiffness of the cable, E S The elastic modulus of the cable; The stiffness K of the cable S The target displacement ΔU of the pier top displacement of the piers before and after the impact on the Gazelle piers satisfies the following formula: In the formula, ΔU represents the displacement reduction of the pier top before and after the impact, which is determined by the design target; K P K represents the longitudinal deformation stiffness of the bridge pier. eq1 The equivalent stiffness of the spring at the top of the impacted pier is obtained by the static stiffness distribution method based on the spring.

4. The structure for improving the longitudinal collision resistance of bridges according to claim 2, characterized in that: When the cables on both sides of the top of the adjacent bridge piers are arranged in a crisscross pattern, the cross-sectional area A of the cables is... S It is determined by the internal forces of the impacted pier and the displacement of the pier top.

Images