# Study on the Anticollision Performance of a New Corrugated Steel Protection System for Bridge Pier

Authors: Guicheng Chen; Haidong Huang; Zhongfu Xiang
Journal: Shock and Vibration
 (2022)

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## Abstract

A new type of corrugated steel protection system (CSP) for the bridge pier is proposed to improve the impact resistance of the bridge pier and reduce the loss caused by the collision of the ship against the pier. A new bolt numerical simulation method and finite element model establishment method are proposed and verified by the impact test. The results show that the new method can effectively simulate the mechanical behavior of bolts and CSP. Parameters analysis was carried out subsequently by the verified finite element model which showed that the energy absorbing ability of CSP increases with corrugated steel pipe wall thickness and its weight decreases. It is concluded that CSP (2.0 mm) is the optimal structural type, and compared with the existing FRP Fender System. The results show that the energy absorbing ability of CSP (2.0 mm) is strong, and its final absorbed energy can reach 86.13% of the total energy of the model structural system (7.22 MJ).


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## Body

## 1. Introduction

Ships often collided with piers of bridges crossing inland rivers and coastal waterways, resulting in accidents, such as damage, collapse, and destruction of the bridge structure. According to AASHTO [1], there were 31 major bridge collapse accidents caused by ships hitting bridge piers worldwide from 1960 to 2002, resulting in 342 deaths. The U.S. Coast Guard [2] recorded 2692 incidents of ships colliding with bridges on inland waterways from 1992 to 2001, with only 61 resulting in economic losses of more than 5 million U.S. dollars. Therefore, ships colliding with bridges seriously threaten people’s lives and property. There are mainly two measures to reduce the losses caused by such accidents. The first measure is to improve the impact resistance of the bridge structure itself. The second one is to add a physical protection system. Improving the impact resistance of the bridge structure itself not only increases the cost of the bridge but also aggravates the damage to the ship involved. The addition of a physical protection system can not only ensure the safety of the bridge and ship structure but also save the cost of bridge construction.The AASHTO [1] introduced research and application scenarios of physical protection systems, such as timber fenders, rubber fenders, concrete fenders, steel fenders, pile-supported systems, dolphin protection, inland protection, and floating protection systems. Svensson [3] summarized the development of anticollision facilities over the last 25 years, gave the application scenarios of 18 anticollision facilities in different regions, and compared the impact force changes before and after the addition. Research on the anticollision performance evaluation and dynamic response of the protection systems, such as a flexible steel rope anticollision device [4], new FRP fender system [5, 6], steel–CFRP combined with an anticollision box [7], and curved-shaped anticollision floating box of a bridge pier with a sandwich structure [8]. Studies have shown that the physical protection system can effectively reduce the peak value of impact force and has a good energy dissipation effect. However, there are disadvantages, such as high cost of composite materials, complex process, difficulty in modular construction, standardized production, and long construction period, and structural optimization research for physical protection systems is lacking. Therefore, a CSP composed of corrugated steel plates and corrugated steel pipes was proposed in combination with the honeycomb structure with good energy absorption and dissipation characteristics [9–11]. This system can be modularized and produced in a standardized manner.At present, corrugated steel has been widely used in the field of construction engineering. Many studies on the characteristics of corrugated steel have been carried out in the course of engineering application. For example, the shear resistance is discussed in references [12–15], and the bending performance is analyzed in references [16–19]. The torsion resistance characteristics are studied in references [20–24], and the seismic performance is examined in references [25–29]. However, deformation energy absorption is another important feature of corrugated steel in physical protection systems. The existing basic research on the deformation and energy absorption of corrugated steel, such as the one conducted by Nassirnia et al. [30], discussed the mechanical properties, section bearing capacity, and energy absorption of hollow corrugated columns. Han et al. [31] found that sandwich structures with aluminum foamed-filled corrugated cores can improve the load-bearing capacity and energy-absorbing capacity through a comparative study of quasistatic experiments. Niknejad et al. [32] used a quasistatic test method to study the energy absorption characteristics of corrugated steel pipes. The research shows that the quasistatic test and finite element method are used to study the shear resistance, bending resistance, torsion resistance, seismic resistance, energy absorption, and other characteristics of a certain type of corrugated steel plate or corrugated steel pipe structure. However, its anticollision performance has not been thoroughly studied; thus, it is of great significance to study the anticollision performance of CSP, which is composed of corrugated steel plate, corrugated steel pipe, and others.In summary, this work proposes a CSP, which can not only improve the impact resistance of the bridge pier but also reduce the damage to the ship and reduce the loss caused by the accident of the ship hitting the bridge. On the basis of parametric research, the verified finite element model is used to simulate the entire impact process, and the time history curves of impact force and total energy and their peak values for each case are obtained. The extreme value analysis method is also used to obtain the optimal structural form of CSP. Finally, the difference between the optimal structure of CSP and the new FRP fender system [6] during the entire impact process are compared under the same conditions (impact energy, impacting barge, bridge pier structure, impact velocity, and angle) to evaluate the anticollision performance of CSP.


## 2. Overview to CSP

The diameter of the corrugated steel pipes can be adjusted according to the channel level to change the number of corrugated steel pipes and corrugated steel plates in the CSP to improve its anticollision performance. The structure of the CSP becomes more complex with the decrease in the diameter of the corrugated steel pipe as shown in Figure1(a). When the CSP is impacted, the corrugated steel plates and the corrugated steel pipes are deformed by the impact, and a large amount of kinetic energy are converted into the internal energy of the CSP. The deformation of CSP can extend the impact time of the ship and reduce the peak value of impact force, thereby ensuring the safety of the bridge and ship structure. In this study, a typical inland river barge with a total weight of 1600 DWT was selected to hit the bridge pier under the protection of the CSP at a velocity of 3 m/s. The CSP structural type that meets the requirements of the channel level collision avoidance is shown in Figure 1(b). (I) depicts the left and right side modules, and the 3D view of the structure is shown in Figure 1(d). (II) shows the front and rear modules, and the 3D view of the structure is shown in Figure 1(c). The corrugated steel pipe and the corrugated steel plate are connected by bolts, and there is no connection between the corrugated steel pipes.Figure 1
Schematic of the CSP structure: (a) complex structure of CSP, (b) CSP structural type used for research, (c) left and right side modules, and (d) front and rear modules.
(a)(b)(c)(d)The elevation and plan views of the CSP are shown in Figures2(a) and 2(b), respectively. The CSP is 15.96 m long, 16.63 m wide, and 3.60 m high. It has an axisymmetric structure. (I) and (I)′ are composed of three corrugated steel pipes, two corrugated steel plates, and several M12 high-strength bolts. (II) and (II)′ are composed of 13 corrugated steel pipes, three corrugated steel plates, and several M12 high-strength bolts. The waveform parameter of the corrugated steel plate is (pitch × depth) 400 mm × 150 mm, and its thickness is 5.00 mm. The outer diameter of the corrugated steel pipe is Φ = 2.0 m, the waveform parameter is (pitch × depth) 200 mm × 55 mm, and its thickness is 2.00, 2.50, 3.00, 3.50, 4.00, 4.50, and 5.00 mm. The corrugated steel plate and corrugated steel pipe in the module are alternately arranged and connected by M12 high-strength bolts. The A–A sectional view is shown in Figure 2(e), and the detailed drawing of the M12 high-strength bolt connection is presented in Figure 2(d). (I) and (I)′ are connected with (II) and (II)′ by the connected part, respectively, as shown in Figure 2(c). The overall structure of the CSP is formed by welding ordinary steel plates.Figure 2
CSP geometric model (unit: mm): (a) elevation view of CSP, (b) plan view of CSP, (c) B detailed drawing of connected part, (d) C detailed drawing of the M12 high-strength bolt connection, and (e) A–A sectional view.
(a)(b)(c)(d)(e)


## 3. Material Model

Jiang et al. [6, 33] introduced in detail the material model of the barge and bridge pier structure selection. The finite element model of the barge is divided into two parts: bow and stern. The stern part uses the ∗MAT_RIGID (∗MAT_020) material model. The bow uses the ∗MAT_PLASTIC_KINEMATIC (∗MAT_003) material model, which has the characteristics of linear isotropy and kinematic hardening. The C50 bridge pier concrete uses the ∗MAT_SCHWER_MURRAY_CAP_MODEL (∗MAT_145) material model, which can effectively simulate the mechanical behavior characteristics of concrete under low-velocity impact [5, 6, 33, 34], and the reinforcement inside the concrete uses the ∗MAT_ELASTIC (∗MAT_001) material model.Ordinary steel plates are formed into corrugated steel pipes or corrugated steel plates after cold forming [35], which improves the yield strength and reduces the plasticity of corrugated steel. The ∗MAT_PIECEWISE_LINEAR_PLASTICITY (∗MAT_024) material model used for corrugated steel can consider isotropic and kinematic hardening plasticity and can define arbitrary stress-strain relationship curves and strain rate effects. The stress-strain curve (ID = 1) of corrugated steel used in numerical simulation is shown in Figure 3, based on the research on steel strain rate by various scholars [36–39]. In the numerical simulation, the material parameters are summarized in Table 1.Figure 3
Stress-strain curve (ID = 1) of corrugated steel.Table 1
Parameters of the materials.
MaterialLS-DYNA modelParametersCorrugated steel∗MAT_024ρ (g/mm3)E (MPa)νFAILLCSSVP7.85e − 3176e30.310.311Bow∗MAT_003ρ (g/mm3)E (MPa)νσ0 (MPa)Et (MPa)Fs7.85e−3210e30.323511800.5Stern∗MAT_ 020ρ (g/mm3)E (MPa)νCM0CON1CON17.85e−3210e30.31.000Reinforcement 1∗MAT_001ρ (g/mm3)E (MPa)ν———7.85e−3210e30.3———Reinforcement 2∗MAT_001ρ (g/mm3)E (MPa)ν———7.85e−3210e30.3———C50∗MAT_145ρ (g/mm3)G (MPa)K (MPa)α (MPa)α1α22.6e − 31.4e40.214.970.830.76θθ1 (MPa−1)θ2 (MPa−1)λλ1 (MPa−1)λ2 (MPa−1)0.3270008.14640.24070.2561β (MPa−1)β1 (MPa−1)β2 (MPa−1)X0 (MPa)D1 (MPa−1)D2 (MPa−1)0.02400.00820.0071108.149.5e − 41.675e − 6WSA−B−A+B+0.0672.01.00.11.00.3


## 4. Establishment and Verification of the Finite Element Model

When the barge hits the bridge pier structure or CSP head-on, it follows the law of conservation of energy. The barge hits the bridge pier head-on, and the impact force time history curve and the bow impact crush depth time history curve obtained by simulation are compared with those provided by reference [6] to verify the effectiveness of the barge and the bridge pier. The simplified finite element model of CSP is verified by a pendulum impact test.


### 4.1. Impact Test Setup

The M12 high-strength bolt is simplified as a beam element combined with the keyword∗CONSTRAINED_NODAL_RIGID_BODY to realize the simulation method of connection with the shell element [40], which will form a small beam element that greatly increases the time cost of numerical calculation. A new simplified simulation method of M12 high-strength bolts is proposed in this work to reduce the high computational cost caused by the simplified simulation method of M12 high-strength bolts. The bolts are regarded as quality points, and the keyword ∗CONSTRAINED_NODAL_RIGID_BODY is used to realize the connection between the shell elements. A pendulum impact test was carried out to verify the newly proposed simplified simulation method for bolts. The geometric model of the impact test is shown in Figure 4(c), based on the existing pendulum impact test [41, 42]. The thickness of the corrugated steel plate and the corrugated steel pipe is 3.5 mm, the wave parameter is (pitch × depth) 400 mm × 150 mm, (pitch × depth) 200 mm × 55 mm; the field test model of column specimen is shown in Figure 4(a), and CSP specimen is shown in Figure 4(b), and the impact speed of the pendulum is 4 m/s. During the test, the GOM-ARAMIS 3D motion and deformation measurement system provided by DOM 3D Ltd. was used to collect the impact test image data. The image acquisition frequency rates are 1200 and 500 Hz. The direction parallel to the initial impact velocity is used as the positive direction when processing the test image data to obtain the test results of the time history curves of displacement, velocity, acceleration, etc.Figure 4
Field test model and geometric model of the impact test. (a) Column specimen, (b) CSP specimen, and (c) geometric model.
(a)(b)(c)


### 4.2. Numerical Simulation of Impact Test

The finite element model of the impact test is shown in Figure5(a). The corrugated steel pipe, corrugated steel plate, ordinary steel plate, and laboratory floor are simulated by shell elements. Meanwhile, the column, base, and pendulum are simulated by solid elements. The commonly used bolt simplification simulation method is shown in Figure 5(b), which simplifies the bolt to beam + rigid body. The newly proposed simplified bolt simulation method, as shown in Figure 5(c), which simplifies the bolt to mass + rigid body, is used to reduce the calculation cost. Two finite element models are established according to different simplification methods of bolts. Numerical calculations are carried out to simulate the impact test process, and the numerical calculation results of time history curves, such as displacement, velocity, and acceleration, are obtained.Figure 5
Simplified finite element model of the impact test: (a) finite element model of the impact test; (b) the bolt is simplified to Beam + rigid body; and (c) the bolt is simplified to mass + rigid body.
(a)(b)(c)


### 4.3. Test and Simulation Results

The comparison of deformation modes between simulation results and test results are shown in Figure6. Under impact, the corrugated steel plate of the CSP is deformed, with the greatest deformation observed in the outer corrugated steel plate. Therefore, the photos of those corrugated steel plate are compared with the simulation results. The results show that the test results and simulation results are basically consistent.Figure 6
Deformation modes of experiment and simulation: (a, b) deformation modes of experiment, (c) the bolt is simplified to beam + rigid body; and (d) the bolt is simplified to mass + rigid body.
(a)(b)(c)(d)The experimental and simulation results of the lateral displacement time history curve at the top of the column are shown in Figure7(a). Each curve has two peaks. The first peak appears around 0.019 s, and the first peak values of each curve are 0.00543, 0.00542, 0.00565, and 0.00728 m. The second peak appears around 0.04 s, and the second peak values of each curve are 0.00317, 0.00314, 0.00156, and 0.00199 m. The calculation result of the first peak values of each curve is slightly smaller than the test result. Meanwhile, the calculation result of the second peak value is larger than the test result. However, the overall trend of the curve is basically consistent.Figure 7
Time history curve of experiment and simulation: (a) the lateral displacement of the top of the column, (b) the lateral velocity of the top of the column, and (c) the lateral acceleration of the top of the column.
(a)(b)(c)The experimental and simulation results of the lateral velocity time history curve at the top of the column are shown in Figure7(b). At 0.012 s where the peak of the lateral velocity time history curve appears, the first peak values of each curve are 0.70, 0.69, 0.42, and 0.70 m/s. The minimum values of each curve appears around 0.023 s, and they are −0.36, −0.35, −0.80, and −0.88 m/s. The results show that the changing trends of the curves are basically consistent.The experimental and simulation results of the lateral acceleration time history curve at the top of the column are shown in Figure7(c). The peak and trough times of the acceleration time history curve are basically the same, and the magnitude of the acceleration is also close. Moreover, the change trends of the curves are basically the same.In summary, the newly proposed simplified bolt simulation method can describe the mechanical behavior of bolted corrugated steel pipe and corrugated steel plate. The comparison results show that the established CSP finite element model is effective.


### 4.4. Establishment of the Finite Element Model

CSP is composed of corrugated steel plates, corrugated steel pipes, bolts, etc. Under impact, CSP absorbs energy through the deformation of corrugated steel plate and corrugated steel pipe and prolongs the impact time to reduce the impact force. The barge, bridge piers, CSP, and other structures are discretized into finite elements for numerical analysis to evaluate the anticollision performance of the CSP, and the time history curves of the impact force and total energy and their peak values were obtained. The finite element model of the barge, bridge pier, and CSP was also verified to ensure the accuracy of the numerical calculation results.The waveform parameter of the corrugated steel plate is (pitch × depth) 400 mm × 150 mm, and the corrugated steel pipe is (pitch × depth) 200 mm × 55 mm, their common specifications [43] are shown in Table 2. The cross-section of corrugated steel plate and the assembly type corrugated steel pipe are shown in Figures 8(a) and 8(b), respectively. The flange connection mode of annular corrugated steel pipe is shown in Figure 8(d). In the finite element analysis of corrugated steel pipe culverts [44–47], the assembly or connection mode of corrugated steel pipe is not considered. Therefore, the assembly and connection mode of corrugated steel pipe is not considered in the establishment of geometric model and finite element model below. The assembly type corrugated steel pipe is regarded as a smooth annular corrugated steel pipe, as shown in Figure 8(c). Moreover, the flange connection of the annular corrugated steel pipe is regarded as a complete annular corrugated steel pipe, as shown in Figure 8(e). The assembly of corrugated steel plate is not considered.Table 2
Common specifications [43] (unit: mm).
Waveform parameterAnnular corrugated steel pipeAssembly type corrugated steel pipeDiameter rangeThickness rangeDiameter rangeThickness range200 mm × 55 mm1250∼30003.00∼6.501500∼100002.00∼8.00400 mm × 150 mm——8000∼200005.00∼8.00Figure 8
Simplification of assembly and flange connections: (a) corrugated steel plate, (b) assembly type corrugated steel pipe, (c) simplification of assembly, (d) flange connection of annular corrugated steel pipe, and (e) simplification of flange connection.The typical inland waterway barge and bridge pier structure used are the same as those utilized to evaluate the anticollision performance of the new FRP fender system to optimize the structure of CSP and evaluate the anticollision performance of its optimal structure [6]. In the research of the new FRP fender system, the peak value of impact force and total energy is the largest in a head-on impact when the barge hits the pier or the protection system at the same velocity and different impact angles. Therefore, the head-on impact (as shown in Figure 9(d)) is taken as an example to discuss the structural optimization of CSP and evaluate its anticollision performance.Figure 9
Finite element model: (a) CSP, (b) bridge pier, (c) barge, and (d) head-on impact.
(a)(b)(c)(d)Figure9(c) depicts a barge with a total weight of 1600 DWT that belongs to the typical standard ship of inland waterways and its finite element model. The barge is divided into two parts: the bow and the stern. The stern part is treated as a rigid body in the numerical calculation, which simplifies the small parts inside the stern, avoids the size of the shell element being considerably small, and increases the cost of numerical analysis and calculation. The stern has a total length of 61 m. The bow is a deformable part, which can simulate the damage of the bow during an impact, and its length is 10 m. The mesh of the bow part is finer than that of the stern part, and the shell element side length of the bow part is in the range of 150–400 mm, with a total of 13,957 shell elements. The side length of the shell elements in the stern part is in the range of 500–800 mm, and there are a total of 4356 shell elements. The internal contact of the bow is simulated by the keyword ∗CONTACT_AUTOMATIC_SINGLE_SURFACE. The contact between the barge and the pier and between the barge and the CSP can be simulated by using the keyword ∗CONTACT_AUTOMATIC_SURFACE_TO_SURFACE. In the simulation, the static and dynamic friction coefficients are 0.3 and 0.2, respectively. In the calculation, the barge hits the pier or the protection system head-on at a velocity of 3 m/s.The pier structure is a flexible thin-walled pier with a cross section of 7 × 2.5 m. The pier structure uses eight-node solid elements, with a total of 8394 solid elements, and the side length of the element is in the range of 250–500 mm, as shown in Figure9(b). The beam element is used to simulate the reinforcement of the pier structure, and the connection between the beam element and the solid element is simulated by using the keyword ∗CONSTRAINED_LAGRANGE_IN_SOLID.The wave parameters of the corrugated steel pipe/plate must be constructed when establishing the finite element model of CSP. The side length of the shell element used in the CSP is in the range of 50–200 mm, with a total of 305,832 shell elements, as shown in Figure9(a). The corrugated steel pipes and the corrugated steel plates are connected by M12 high-strength bolts, and the high-strength bolts are regarded as nondeformable bodies. According to the bolt numerical simulation method [33], the thickness of corrugated steel pipe and corrugated steel plate is between 3.50 mm and 5.00 mm. The high-strength bolts must be simplified into quality points combined with ∗CONSTRAINED_NODAL_RIGID_BODY to connect corrugated steel pipes, corrugated steel plates, and bolts. The verification of this simplified method will be discussed in the subsequent chapters. The connection between the corrugated steel plate and ordinary steel plate is simulated by the keyword ∗CONTACT_TIE_NODES_TO_SURFACE, and (I), (I)′, (II), and (II)′ are connected with the connecting parts to form the overall structure of the CSP. The keyword ∗CONTACT_AUTOMATIC_SINGLE_SURFACE simulates the contact of the internal structure of the CSP. Meanwhile, the keyword ∗CONTACT_AUTOMATIC_SURFACE_TO_SURFACE simulates the contact of the CSP with bridge piers, ships, and other structures.


### 4.5. Verification of the Finite Element Model of Barge and Bridge Pier

A finite element model of the barge and bridge pier structure was established according to the barge and bridge parameters provided in reference [5, 6]. The time history curves of the impact force and bow impact crush depth obtained by simulation are compared with that provided by reference [6] to validate the finite element model of the barge and bridge pier.A barge with a total weight of 1600 DWT hits the bridge pier without a protection system head-on at a velocity of 3 m/s. The time history curve of the impact force obtained by simulation and provided by reference [6] is shown in Figure 10(a). The peak values of the impact force obtained by the simulation and provided by reference [6] are both 47.6 MN, and the impact time is 0.6 s. The time history curve of the impact force obtained by the simulation is smoother than that provided by reference [6]. However, the trends of the two curves are basically consistent. The time history curve of the bow impact crush depth is shown in Figure 10(b). The maximum values of the bow impact crush depth obtained by the simulation and provided by reference [6] are both 0.21 m, and the maximum appearance time is 0.4 s. The changing trends of the two curves are basically consistent. The results show that the finite element model of the barge and the bridge pier is effective.Figure 10
Time history curve of head-on impact at a velocity of 3 m/s: (a) impact force and (b) barge crush depth.
(a)(b)In summary, the finite element model established based on the geometric parameters of the barge, pier, and CSP can effectively simulate the entire process of the barge head-on impact with the bridge pier protected by the CSP.


## 4.1. Impact Test Setup

The M12 high-strength bolt is simplified as a beam element combined with the keyword∗CONSTRAINED_NODAL_RIGID_BODY to realize the simulation method of connection with the shell element [40], which will form a small beam element that greatly increases the time cost of numerical calculation. A new simplified simulation method of M12 high-strength bolts is proposed in this work to reduce the high computational cost caused by the simplified simulation method of M12 high-strength bolts. The bolts are regarded as quality points, and the keyword ∗CONSTRAINED_NODAL_RIGID_BODY is used to realize the connection between the shell elements. A pendulum impact test was carried out to verify the newly proposed simplified simulation method for bolts. The geometric model of the impact test is shown in Figure 4(c), based on the existing pendulum impact test [41, 42]. The thickness of the corrugated steel plate and the corrugated steel pipe is 3.5 mm, the wave parameter is (pitch × depth) 400 mm × 150 mm, (pitch × depth) 200 mm × 55 mm; the field test model of column specimen is shown in Figure 4(a), and CSP specimen is shown in Figure 4(b), and the impact speed of the pendulum is 4 m/s. During the test, the GOM-ARAMIS 3D motion and deformation measurement system provided by DOM 3D Ltd. was used to collect the impact test image data. The image acquisition frequency rates are 1200 and 500 Hz. The direction parallel to the initial impact velocity is used as the positive direction when processing the test image data to obtain the test results of the time history curves of displacement, velocity, acceleration, etc.Figure 4
Field test model and geometric model of the impact test. (a) Column specimen, (b) CSP specimen, and (c) geometric model.
(a)(b)(c)


## 4.2. Numerical Simulation of Impact Test

The finite element model of the impact test is shown in Figure5(a). The corrugated steel pipe, corrugated steel plate, ordinary steel plate, and laboratory floor are simulated by shell elements. Meanwhile, the column, base, and pendulum are simulated by solid elements. The commonly used bolt simplification simulation method is shown in Figure 5(b), which simplifies the bolt to beam + rigid body. The newly proposed simplified bolt simulation method, as shown in Figure 5(c), which simplifies the bolt to mass + rigid body, is used to reduce the calculation cost. Two finite element models are established according to different simplification methods of bolts. Numerical calculations are carried out to simulate the impact test process, and the numerical calculation results of time history curves, such as displacement, velocity, and acceleration, are obtained.Figure 5
Simplified finite element model of the impact test: (a) finite element model of the impact test; (b) the bolt is simplified to Beam + rigid body; and (c) the bolt is simplified to mass + rigid body.
(a)(b)(c)


## 4.3. Test and Simulation Results

The comparison of deformation modes between simulation results and test results are shown in Figure6. Under impact, the corrugated steel plate of the CSP is deformed, with the greatest deformation observed in the outer corrugated steel plate. Therefore, the photos of those corrugated steel plate are compared with the simulation results. The results show that the test results and simulation results are basically consistent.Figure 6
Deformation modes of experiment and simulation: (a, b) deformation modes of experiment, (c) the bolt is simplified to beam + rigid body; and (d) the bolt is simplified to mass + rigid body.
(a)(b)(c)(d)The experimental and simulation results of the lateral displacement time history curve at the top of the column are shown in Figure7(a). Each curve has two peaks. The first peak appears around 0.019 s, and the first peak values of each curve are 0.00543, 0.00542, 0.00565, and 0.00728 m. The second peak appears around 0.04 s, and the second peak values of each curve are 0.00317, 0.00314, 0.00156, and 0.00199 m. The calculation result of the first peak values of each curve is slightly smaller than the test result. Meanwhile, the calculation result of the second peak value is larger than the test result. However, the overall trend of the curve is basically consistent.Figure 7
Time history curve of experiment and simulation: (a) the lateral displacement of the top of the column, (b) the lateral velocity of the top of the column, and (c) the lateral acceleration of the top of the column.
(a)(b)(c)The experimental and simulation results of the lateral velocity time history curve at the top of the column are shown in Figure7(b). At 0.012 s where the peak of the lateral velocity time history curve appears, the first peak values of each curve are 0.70, 0.69, 0.42, and 0.70 m/s. The minimum values of each curve appears around 0.023 s, and they are −0.36, −0.35, −0.80, and −0.88 m/s. The results show that the changing trends of the curves are basically consistent.The experimental and simulation results of the lateral acceleration time history curve at the top of the column are shown in Figure7(c). The peak and trough times of the acceleration time history curve are basically the same, and the magnitude of the acceleration is also close. Moreover, the change trends of the curves are basically the same.In summary, the newly proposed simplified bolt simulation method can describe the mechanical behavior of bolted corrugated steel pipe and corrugated steel plate. The comparison results show that the established CSP finite element model is effective.


## 4.4. Establishment of the Finite Element Model

CSP is composed of corrugated steel plates, corrugated steel pipes, bolts, etc. Under impact, CSP absorbs energy through the deformation of corrugated steel plate and corrugated steel pipe and prolongs the impact time to reduce the impact force. The barge, bridge piers, CSP, and other structures are discretized into finite elements for numerical analysis to evaluate the anticollision performance of the CSP, and the time history curves of the impact force and total energy and their peak values were obtained. The finite element model of the barge, bridge pier, and CSP was also verified to ensure the accuracy of the numerical calculation results.The waveform parameter of the corrugated steel plate is (pitch × depth) 400 mm × 150 mm, and the corrugated steel pipe is (pitch × depth) 200 mm × 55 mm, their common specifications [43] are shown in Table 2. The cross-section of corrugated steel plate and the assembly type corrugated steel pipe are shown in Figures 8(a) and 8(b), respectively. The flange connection mode of annular corrugated steel pipe is shown in Figure 8(d). In the finite element analysis of corrugated steel pipe culverts [44–47], the assembly or connection mode of corrugated steel pipe is not considered. Therefore, the assembly and connection mode of corrugated steel pipe is not considered in the establishment of geometric model and finite element model below. The assembly type corrugated steel pipe is regarded as a smooth annular corrugated steel pipe, as shown in Figure 8(c). Moreover, the flange connection of the annular corrugated steel pipe is regarded as a complete annular corrugated steel pipe, as shown in Figure 8(e). The assembly of corrugated steel plate is not considered.Table 2
Common specifications [43] (unit: mm).
Waveform parameterAnnular corrugated steel pipeAssembly type corrugated steel pipeDiameter rangeThickness rangeDiameter rangeThickness range200 mm × 55 mm1250∼30003.00∼6.501500∼100002.00∼8.00400 mm × 150 mm——8000∼200005.00∼8.00Figure 8
Simplification of assembly and flange connections: (a) corrugated steel plate, (b) assembly type corrugated steel pipe, (c) simplification of assembly, (d) flange connection of annular corrugated steel pipe, and (e) simplification of flange connection.The typical inland waterway barge and bridge pier structure used are the same as those utilized to evaluate the anticollision performance of the new FRP fender system to optimize the structure of CSP and evaluate the anticollision performance of its optimal structure [6]. In the research of the new FRP fender system, the peak value of impact force and total energy is the largest in a head-on impact when the barge hits the pier or the protection system at the same velocity and different impact angles. Therefore, the head-on impact (as shown in Figure 9(d)) is taken as an example to discuss the structural optimization of CSP and evaluate its anticollision performance.Figure 9
Finite element model: (a) CSP, (b) bridge pier, (c) barge, and (d) head-on impact.
(a)(b)(c)(d)Figure9(c) depicts a barge with a total weight of 1600 DWT that belongs to the typical standard ship of inland waterways and its finite element model. The barge is divided into two parts: the bow and the stern. The stern part is treated as a rigid body in the numerical calculation, which simplifies the small parts inside the stern, avoids the size of the shell element being considerably small, and increases the cost of numerical analysis and calculation. The stern has a total length of 61 m. The bow is a deformable part, which can simulate the damage of the bow during an impact, and its length is 10 m. The mesh of the bow part is finer than that of the stern part, and the shell element side length of the bow part is in the range of 150–400 mm, with a total of 13,957 shell elements. The side length of the shell elements in the stern part is in the range of 500–800 mm, and there are a total of 4356 shell elements. The internal contact of the bow is simulated by the keyword ∗CONTACT_AUTOMATIC_SINGLE_SURFACE. The contact between the barge and the pier and between the barge and the CSP can be simulated by using the keyword ∗CONTACT_AUTOMATIC_SURFACE_TO_SURFACE. In the simulation, the static and dynamic friction coefficients are 0.3 and 0.2, respectively. In the calculation, the barge hits the pier or the protection system head-on at a velocity of 3 m/s.The pier structure is a flexible thin-walled pier with a cross section of 7 × 2.5 m. The pier structure uses eight-node solid elements, with a total of 8394 solid elements, and the side length of the element is in the range of 250–500 mm, as shown in Figure9(b). The beam element is used to simulate the reinforcement of the pier structure, and the connection between the beam element and the solid element is simulated by using the keyword ∗CONSTRAINED_LAGRANGE_IN_SOLID.The wave parameters of the corrugated steel pipe/plate must be constructed when establishing the finite element model of CSP. The side length of the shell element used in the CSP is in the range of 50–200 mm, with a total of 305,832 shell elements, as shown in Figure9(a). The corrugated steel pipes and the corrugated steel plates are connected by M12 high-strength bolts, and the high-strength bolts are regarded as nondeformable bodies. According to the bolt numerical simulation method [33], the thickness of corrugated steel pipe and corrugated steel plate is between 3.50 mm and 5.00 mm. The high-strength bolts must be simplified into quality points combined with ∗CONSTRAINED_NODAL_RIGID_BODY to connect corrugated steel pipes, corrugated steel plates, and bolts. The verification of this simplified method will be discussed in the subsequent chapters. The connection between the corrugated steel plate and ordinary steel plate is simulated by the keyword ∗CONTACT_TIE_NODES_TO_SURFACE, and (I), (I)′, (II), and (II)′ are connected with the connecting parts to form the overall structure of the CSP. The keyword ∗CONTACT_AUTOMATIC_SINGLE_SURFACE simulates the contact of the internal structure of the CSP. Meanwhile, the keyword ∗CONTACT_AUTOMATIC_SURFACE_TO_SURFACE simulates the contact of the CSP with bridge piers, ships, and other structures.


## 4.5. Verification of the Finite Element Model of Barge and Bridge Pier

A finite element model of the barge and bridge pier structure was established according to the barge and bridge parameters provided in reference [5, 6]. The time history curves of the impact force and bow impact crush depth obtained by simulation are compared with that provided by reference [6] to validate the finite element model of the barge and bridge pier.A barge with a total weight of 1600 DWT hits the bridge pier without a protection system head-on at a velocity of 3 m/s. The time history curve of the impact force obtained by simulation and provided by reference [6] is shown in Figure 10(a). The peak values of the impact force obtained by the simulation and provided by reference [6] are both 47.6 MN, and the impact time is 0.6 s. The time history curve of the impact force obtained by the simulation is smoother than that provided by reference [6]. However, the trends of the two curves are basically consistent. The time history curve of the bow impact crush depth is shown in Figure 10(b). The maximum values of the bow impact crush depth obtained by the simulation and provided by reference [6] are both 0.21 m, and the maximum appearance time is 0.4 s. The changing trends of the two curves are basically consistent. The results show that the finite element model of the barge and the bridge pier is effective.Figure 10
Time history curve of head-on impact at a velocity of 3 m/s: (a) impact force and (b) barge crush depth.
(a)(b)In summary, the finite element model established based on the geometric parameters of the barge, pier, and CSP can effectively simulate the entire process of the barge head-on impact with the bridge pier protected by the CSP.


## 5. Simulation Results

This work aims to optimize the structure of the CSP protection system and evaluate the anticollision performance of the CSP. When the impact energy and the outer diameter of the corrugated steel pipe are constant, and the plate thickness of the CSP changes from 1.50 mm to 3.50 mm, there are five cases in which the barge hits the bridge pier protected by the CSP head-on at a velocity of 3 m/s. The time history curves of the impact force and total energy (kinetic energy + internal energy) obtained by simulation for each case are shown in Figure11. The parameter of each case and the peak values of the simulation results are summarized in Table 3.Figure 11
Time history curves of each case: (a) impact force, (b) total energy of CSP, (c) total energy of bridge piers, and (d) total energy of barge.
(a)(b)(c)(d)Table 3
Parameters and calculation result peak.
CaseThickness (mm)Weight (kg)Peak impact force (MN)Peak total energy (MJ)Ship-CSPCSP-pierShip(min)CSP(max)Pier(max)CSP (2.0 mm)2.047997.13.984.160.066.660.04CSP (2.5 mm)2.551189.54.954.980.056.690.07CSP (3.0 mm)3.054390.75.756.470.046.660.10CSP (3.5 mm)3.557579.76.616.870.056.670.14CSP (4.0 mm)4.060754.67.387.620.056.610.21CSP (4.5 mm)4.564024.97.978.040.056.600.24CSP (5.0 mm)5.067139.58.448.490.056.570.25The time history curve of impact force in each case is shown in Figure11(a). The ship-CSP (2.0 mm) curve has a peak value of 3.98 MN at 1.17 s, and the CSP-pier (2.0 mm) curve has a peak value of 4.16 MN at 1.34 s. The total impact time is 2.38 s. The ship-CSP (2.5 mm) curve has a peak value of 4.95 MN at 0.63 s, and the CSP-pier (2.5 mm) curve has a peak value of 4.98 MN at 0.66 s. The impact time is 1.98 s. The ship-CSP (3.0 mm) curve has a peak value of 5.75 MN at 0.79 s, and the CSP-pier (3.0 mm) curve has a peak value of 6.47 MN at 0.66 s. The impact time is 1.78 s in total. The ship-CSP (3.5 mm) curve has a peak value of 6.61 MN at 0.82 s, and the CSP-pier (3.5 mm) curve has a peak value of 6.87 MN at 0.86 s. The impact time is 1.62 s. The ship-CSP (4.0 mm) curve has a peak value of 7.38 MN at 0.79 s, and the CSP-pier (4.0 mm) curve has a peak value of 7.62 MN at 0.73 s. The total impact time is 1.38 s. The ship-CSP (4.5 mm) curve has a peak value of 7.97 MN at 0.72 s, and the CSP-pier (4.5 mm) curve has a peak value of 8.04 MN at 0.74 s. The total impact time is 1.30 s. The ship-CSP (5.0 mm) curve has a peak value of 8.44 MN at 0.67 s, and the CSP-pier (5.00 mm) curve has a peak value of 8.49 MN at 0.64 s. The total impact time is 1.20 s. The results show that the peak value of impact force increases with the increase in the plate thickness of CSP, and the impact time decreases. The peak value of impact force of each case accounts for approximately 8.74% to 17.84% of the peak value of impact force (47.6 MN) of the bridge pier without a protective system.The total energy time history curve of CSP in each case is shown in Figure11(b). The CSP total energy time history curve of CSP (2.0 mm) has a peak value of 6.66 MJ at 1.47 s and tends to a stable value of 6.22 MJ after 2.76 s. The CSP total energy time history curve of CSP (2.5 mm) has a peak value of 6.69 MJ at 1.23 s and tends to a stable value of 6.19 MJ after 1.83 s. The CSP total energy time history curve of CSP (3.0 mm) has a peak value of 6.66 MJ at 1.08 s and tends to a stable value of 6.06 MJ after 1.65 s. The CSP total energy time history curve of CSP (3.5 mm) has a peak value of 6.67 MJ at 0.96 s and tends to a stable value of 5.94 MJ after 1.50 s. The CSP total energy time history curve of CSP (4.0 mm) has a peak value of 6.61 MJ at 0.84 s and tends to a stable value of 5.82 MJ after 1.35 s. The CSP total energy time history curve of CSP (4.5 mm) has a peak value of 6.60 MJ at 0.81 s and tends to a stable value of 5.72 MJ after 1.29 s. The CSP total energy time history curve of CSP 5.0 mm) has a peak value of 6.57 MJ at 0.75 s and tends to a stable value of 65.64 MJ after 1.17 s. The results show that the peak values of the total energy of CSP are close with the increase in the plate thickness of CSP. However, the time for the peaks to appear decreases. The total energy peak value of CSP in each case accounts for approximately 90.97% to 92.63% of the total energy of the model structural system (7.22 MJ), and it accounts for approximately 78.09% to 86.13% of the total energy of the model structural system (7.22 MJ) when it stabilizes.The total energy time history curve of the bridge piers of each case is shown in Figure11(c). The bridge pier total energy time history curve of CSP (2.0 mm) has a peak value of 0.04 MJ at 0.63 s and tends to a stable value of 0.02 MJ after 2.23 s. The bridge pier total energy time history curve of CSP (2.5 mm) has a peak value of 0.07 MJ at 0.66 s and tends to a stable value of 0.03 MJ after 1.83 s. The bridge pier total energy time history curve of CSP (3.0 mm) has a peak value of 0.10 MJ at 1.05 s and tends to a stable value of 0.06 MJ after 1.65 s. The bridge pier total energy time history curve of CSP (3.5 mm) has a peak value of 0.14 MJ at 0.87 s and tends to a stable value of 0.09 MJ after 1.50 s. The bridge pier total energy time history curve of CSP (4.0 mm) has a peak value of 0.21 MJ at 0.9 s and tends to a stable value of 0.16 MJ after 1.35 s. The bridge pier total energy time history curve of CSP (4.5 mm) has a peak value of 0.24 MJ at 0.87 s and tends to a stable value of 0.18 MJ after 1.20 s. The bridge pier total energy time history curve of CSP (5.0 mm) has a peak value of 0.25 MJ at 0.78 s and tends to a stable value of 0.19 MJ after 1.08 s. The results show that the peak value of the bridge pier total energy increases with the increase in the plate thickness of CSP. However, the time for the peak value to appear decreases. The peak value of the bridge pier total energy in each case accounts for approximately 0.51% to 3.39% of the total energy of the model structural system (7.22 MJ). When it tends to be a stable value, it accounts for approximately 0.21% to 2.63% of the total energy of the model structural system (7.22 MJ).The total energy time history curves of the barge in each case are shown in Figure11(d). The barge total energy time history curve of CSP (2.0 mm) has minimum value of 0.06 MJ at 1.47 s and tends to a stable value of 0.54 MJ after 2.25 s. The barge total energy time history curve of CSP (2.5 mm) has a minimum value of 0.05 MJ at 1.23 s and tends to a stable value of 0.58 MJ after 1.83 s. The barge total energy time history curve of CSP (3.0 mm) has a minimum value of 0.04 MJ at 1.08 s and tends to a stable value of 0.68 MJ after 1.68 s. The barge total energy time history curve of CSP (3.5 mm) has a minimum value of 0.05 MJ at 0.96 s and tends to a stable value of 0.83 MJ after 1.50 s. The barge total energy time history curve of CSP (4.0 mm) has a minimum value of 0.05 MJ at 0.87 s and tends to a stable value of 0.95 MJ after 1.35 s. The barge total energy time history curve of CSP (4.5 mm) has a minimum value of 0.05 MJ at 2.01 s and tends to a stable value of 1.02 MJ after 1.29 s. The barge total energy time history curve of CSP (5.0 mm) has a minimum value of 0.05 MJ at 0.75 s and tends to a stable value of 1.05 MJ after 1.20 s. The results show that the time to peak value of barge total energy decreases with the increase in the plate thickness of CSP, and the peak value of barge total energy is similar. The peak value of the barge total energy in each case accounts for approximately 0.57% to 0.82% of the total energy of the model structural system (7.22 MJ). When it tends to be a stable value, it accounts for approximately 7.52% to 14.54% of the total energy of the model structural system (7.22 MJ).In summary, the results show that the CSP in each case can ensure the structural safety of ships and bridge piers during the collision.


## 6. Peak Analysis

The parameterization (plate thickness and weight) of CSP was studied to derive the optimal structural type, and the time history curves of impact force and total energy and their peak values in each case were obtained. After fitting each peak value, the relationship curve between the plate thickness or weight of the CSP and peak value is shown in Figure12. To analyze each relationship curve, the optimal structural type of CSP is obtained.Figure 12
Relationship curve: (a, b) the relationship curves between the plate thickness or weight of the CSP and the peak value of bridge pier impact force, respectively; (c, d) the relationship curves between the plate thickness or weight of the CSP and the peak value of CSP total energy, respectively; (e, f) the relationship curves between the plate thickness or weight of the CSP and the peak value of the bridge pier total energy, respectively.
(a)(b)(c)(d)(e)(f)The relationship curve between the peak value of bridge pier impact force and the thickness of the CSP is shown in Figure12(a). The curve decreases with the increase in the plate thickness and then increase, and a minimum point (2.00, 4.16) exists; hence, the optimal value of the thickness is 2.00 mm. The relationship curve between the peak value of bridge pier impact force and the weight of CSP is shown in Figure 12(b). The curve first decreases with the increase in weight and then increases. A minimum point (47997.10, 4.16) exists. Hence, the optimal value of the weight is 47997.10 kg.The relationship curve between the peak value of CSP total energy and the plate thickness of CSP is shown in Figure12(c). The curve first increases with the increase in the plate thickness and then decreases. A maximum point (2.00, 6.66) exists; hence, the optimal value of the thickness is 2.00 mm. The relationship curve between the peak value of CSP total energy and the weight of CSP is shown in Figure 12(b). The curve first increases with the increase in weight and then decreases. A maximum point (47997.10 6.66) exists. Hence, the optimal value of weight is 47997.10 kg.The relationship between the peak value of the bridge pier total energy and the plate thickness of the CSP is shown in Figure12(c). The curve first decreases with the increase in the plate thickness and then increases, and a minimum point (2.00, 0.04) exists; hence, the optimal value of the thickness is 2.00 mm. The relationship curve between the peak value of the bridge pier total energy and the weight of the CSP is shown in Figure 12(b). The curve first decreases with the increase in weight and then increases. A minimum point (47997.10, 0.04) exists; hence, the optimal value of the weight is 47997.10 kg.In summary, the energy absorbing ability of CSP increases with the decrease of the wall thickness of corrugated steel pipe and its weight. CSP (2.00 mm) is the optimal structural type.


## 7. Anticollision Performance Evaluation

The process of a barge hitting CSP (2.0 mm) or new FRP fender system (FRP) [6] head-on at a velocity of 3 m/s is analyzed under the same conditions (barge, bridge pier structure, impact velocity, and angle) to evaluate the anticollision performance of CSP (2.00 mm). The time history curves of impact force, total energy of protection system, impact crush depth of the protection system, and the total energy of bridge piers obtained by simulation and provided by reference [6] are shown in Figure 13. This study compared the difference of each time history curve to evaluate the anticollision performance of CSP (2.00 mm).Figure 13
Time history curve of a barge hitting a CSP (2.50 mm) or a new FRP fender system head-on at 3 m/s: (a) impact force, (b) total energy of CSP, (c) impact crush depth of CSP or FRP, and (d) total energy of bridge pier.
(a)(b)(c)(d)The time history curve of impact force is shown in Figure13(a). The peak values for the impact force of the ship-CSP (2.0 mm) and the CSP (2.0 mm)-pier are 3.98 and 4.16 MN, respectively, and the impact time is 2.38 s. Meanwhile, the peak values for the impact force of the ship-FRP and the FRP-pier are 8.80 and 5.86 MN, and the impact time is 2.40 s. The impact time of a barge impacting FRP is 0.30 s longer than that of a barge hitting a CSP (2.0 mm). The peak value for the impact force of ship-CSP (2.0 mm) is 4.82 MN smaller than that of ship-FRP. The peak value for the impact force of CSP (2.0 mm)-pier is 1.70 MN smaller than that of FRP-pier. The results show that CSP (2.0 mm) has better anticollision performance than FRP, which effectively reduces the peak value of impact force experienced by barges and bridge piers during impact and ensures the structural safety of barges and bridge piers.The total energy time history curve of CSP (2.0 mm) and FRP is shown in Figure13(b). The barge hits CSP (2.0 mm), and the total energy of CSP (2.0 mm) reaches a peak value of 6.66 MJ at 1.47 s and tends to a stabilized value of 6.20 MJ at 2.25 s. When the barge hits FRP, the total energy of FRP reaches a peak value of 5.13 MJ at 1.47 s and gradually decreases to a certain value. The peak value of CSP (2.0 mm) total energy is 1.53 MJ larger than that of FRP. The results show that CSP (2.0 mm) has better anticollision performance than FRP. The peak value of CSP (2.0 mm) total energy can reach 92.22% of the total energy of the model structural system (7.22 MJ). The peak value of FRP total energy is only 71.05% of the total energy of the model structural system (7.22 MJ).The impact crush depth time history curve of CSP (2.0 mm) and FRP is shown in Figure13(c). The barge hits CSP (2.0 mm), and the impact crush depth of CSP (2.0 mm) reaches a peak value of 2.02 m at 1.47 s and then tends to a stabilized value of 1.74 m at 2.28 s. When the barge hits FRP, the impact crush depth of FRP reaches a peak value of 2.04 m at 1.62 s and then gradually decreases to a certain value. The peak value for the impact crush depth of CSP (2.0 mm) is 0.02 m smaller than that of FRP. However, the stable value for the impact crush depth of CSP (2.0 mm) is larger than that of FRP. The results show that the elastic recovery of FRP is stronger than that of CSP (2.0 mm). The elastic recovery of FRP will transfer energy to the barge. The energy absorbed by CSP (2.0 mm) due to plastic deformation reached 86.13% of the total energy of the model structural system (7.22 MJ).The time history curve of the bridge pier total energy is shown in Figure13(d). The barge hits the CSP (2.0 mm), and the bridge pier total energy of the CSP (2.0 mm) reaches a peak value of 0.04 MJ at 1.47 s and then tends to a stabilized value of 0.02 MJ at 2.23 s. The barge hits the FRP. At 1.69 s, the total energy of the FRP pier reaches a peak value of 0.29 MJ and then gradually decreases to a certain value. The peak value for the bridge pier total energy of CSP (2.0 mm) is 0.25 MJ smaller than that of FRP. The results show that CSP (2.0 mm) has better anticollision performance than FRP. The peak value for the bridge pier total energy of CSP (2.50 mm) can reach 0.51% of the total energy of the model structural system (7.22 MJ), but that for the FRP can reach 4.01%.In summary, the peak value for the impact force of CSP (2.0 mm) is smaller than that of FRP during the impact. The peak value for the impact crush depth of CSP (2.0 mm) is smaller than that of FRP. The peak value for the total energy bridge pier of the CSP (2.0 mm) is smaller than that of FRP. The peak value for CSP total energy of the CSP (2.0 mm) is larger than that of FRP. Therefore, the anticollision performance of CSP (2.50 mm) is stronger than that of FRP.


## 8. Conclusion

This paper studies the anticollision performance of CSP, proposes, and verifies the bolt numerical simulation method and finite element modeling method; parameters analysis was carried out to deduce the optimal structural form of CSP, and its anticollision performance is evaluated. The following conclusions are obtained:(1)
The corrugated steel protection system for the bridge can improve the impact resistance of the bridge pier and ensure the structural safety of the bridge and the ship.(2)
The finite element model established by using the new bolt numerical simulation method and numerical model establishment method can accurately simulate the whole impact process. The results of parameter analysis show that the energy absorbing ability of CSP increases with the decrease of the wall thickness of corrugated steel pipe and its weight and deduced that its optimal structural type is CSP (2.00 mm).(3)
Under the same conditions, compared with the new FRP fender system to evaluate the anticollision performance of CSP (2.00 mm), the results show that CSP can ensure the structural safety of ships and bridge piers during the collision and the energy absorbed by CSP (2.0 mm) reaches 86.13% of the total energy of the model structural system (7.22 MJ),



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*Source: 1263190-2022-03-31.xml*