Seismic Resilience Assessment of the Hybrid Bridge Pier Based on Fragility Analysis

Jianpeng Sun,Weichao Xu,Zihan Tan 한국강구조학회 2024 International Journal of Steel Structures Vol.24 No.2

At present, the seismic structure of recoverable functional bridges based on seismic resilience is one of the hotspots in bridge seismic engineering research. Therefore, a new type of hybrid piers is designed in this paper, which mainly relies on replaceable components to achieve repairable structural performance after earthquakes. At the same time, four-level seismic fortifi cation objectives based on seismic resilience is proposed, and the follow-up stiff ness phenomenon is found on this basis. The fi nite element software OPENSEES was used to perform IDA analysis on a hybrid pier and an ordinary reinforced concrete (RC) pier. The fragility curves and seismic resilience curves of two piers were compared, and the seismic resilience performance and the follow-up stiff ness phenomenon of the hybrid pier were studied. The results show that under the action of diff erent seismic waves, the top displacement angle of the pier of the hybrid pier is slightly larger than that of the ordinary RC pier, but the overall diff erence is not large. The fragility curve of the hybrid pier is slightly larger than that of the ordinary RC pier. However, with the damage to the hybrid pier, the follow-up stiff ness phenomenon impacts the seismic performance, which reduces the seismic force acting on the structure and improves the seismic resilience of the structure. The post-earthquake recovery time of two piers under diff erent damage states was determined. Combined with the fragility curves, the seismic resilience curves of two piers were presented. The resilient index of the hybrid pier was always maintained at 0.9–1, and the seismic resilience performance was excellent.

Bridge Dynamic Deflection and Damage Analysis Based on Transfer Matrix of Multibody System

Jianpeng Sun,Yingbiao Jiang 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.3

To realize the bridge state assessment and damage diagnosis, the vibration transfer matrix of the vehicle-bridge coupling system is established based on the discrete-time transfer matrix method of the multibody system, and the correctness of the derived transfer matrix is verified. The coupling vibration of vehicle passing through the bridge is analyzed. The deflection of each point of the bridge propagates forward in the form of fluctuation when the vehicle passes the bridge uniformly. The dynamic deflection of bridge decreases exponentially with the increase of vehicle speed. The dynamic deflection has the certain sensitivity to the injured unit, which can reflect the injured unit. The curvature difference of uniform load surface is calculated to carry out the damage location analysis of the bridge, and the obtained results can determine the specific location of the damage. With the increase of damage degree, the value of the same unit increases, and the diagnosis of damage location and degree is presented in the form of a peak.

Seismic Resilience-Based Design Method for Hybrid Bridge Pier Under Four-Level Seismic Fortifications

Jianpeng Sun,Zihan Tan 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.5

The hybrid bridge pier can be damaged in stages under earthquakes, and have great repairability after earthquakes, but the existing seismic fortifi cation objectives cannot refl ect the superiority of the hybrid bridge pier. Therefore, higher seismic fortifi cation objectives and the corresponding seismic design method are needed for the hybrid bridge pier. A design example of the hybrid bridge pier was presented. Combined with the seismic ground motion parameter zonation map of China, the four-level seismic fortifi cation objective of the hybrid bridge pier based on seismic resilience is proposed. By formulating the material and structural parameters of the hybrid bridge pier, the seismic force of the pier under the four-level earthquake resistance is calculated. It is shown that with the deepening of the damage degree of the pier, the decrease of the structural stiff ness leads to the increase of the natural period of vibration of the structure, which leads to the decrease of the seismic force acting on the structure, and thus the concept of the follow-up stiff ness is proposed.

Key Construction Technology and Monitoring of Long-Span Steel Box Tied Arch Bridge

Jianpeng Sun,Jinbin Li,Yingbiao Jiang,Xiaogang Ma,Zihan Tan,Gaolin Zhufu 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.1

As a composite system bridge, half-through steel box tied arch bridge combines the arch mainly bearing pressure and the beam mainly bearing bending moment, gives full play to their respective advantages, and has the two characteristics of large span capacity of arch bridge and strong adaptability of simply supported beam bridge to foundation. However, in the construction process, due to the complex construction technology and structural stress behavior, the hoisting of arch rib, the tensioning of tie rod and suspender are accompanied by the change of internal load, which is a challenge for bridge construction. Taking the Lancang River Liming Bridge in Xishuangbanna, Yunnan Province as an example, this paper introduces a new construction scheme of arch bridge, introduces the structural characteristics of cable hoisting system, and puts forward the construction monitoring method. The response of arch rib, suspender, tie rod and main beam is monitored by health monitoring system and compared with the analysis results of finite element model to ensure that the stress and deformation of the structure under various working conditions are in a reasonable state. The results show that the proposed construction scheme can meet the safety and quality requirements of bridge construction, and the finite element model can reasonably predict the bridge behavior in construction. This study is expected to promote the construction of long-span half through steel box tied arch bridge.

Mechanical Behavior of Laminated Rubber Isolation Bearing with Buckling Steel Plate

Jianpeng Sun,Gaolin Zhufu 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.4

To improve the ability of disaster prevention and mitigation of bridges and realize the seismic resilience of traffi c, this paper combines the elastic buckling characteristics of steel plates with the mechanical properties of laminated rubber bearings based on the principle of seismic isolation, and proposes a steel plate-laminated rubber composite seismic isolation bearing. The mechanical properties of steel plates were analyzed by ABAQUS software, and it was found that the shear stiff ness of the steel plates before and after buckling had bilinear characteristics. The stiff ness of the steel plate, the stiff ness ratio before and after buckling, and the critical buckling load decreased with the increase of height-width ratio. According to the numerical regression, the precise formulas of the initial shear stiff ness, the stiff ness ratio before and after buckling, and the critical buckling load of the steel plate are proposed. Finally, by studying the seismic performance parameters of the alternative seismic isolation bearing, such as dissipation energy, shear stiff ness, and equivalent viscous damping coeffi cient, the results show that the outer steel plate of the alternative type of bearing is in parallel with the rubber. The peripheral steel plate improves the overall energy dissipation capacity of the bearing. Under reciprocating load, the bearing exhibits threestage characteristics, which can meet the performance requirements of bridge earthquake prevention and disaster reduction.

Study on the Design Method of Ring Groove Rivet Joint in Aluminum Alloy Structure

Jianpeng Sun,Xiaomeng Qu,Chang Gao 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.1

In this paper, the infl uence of the two main parameters of end distance and edge distance on high strength aluminum alloy ring groove rivet node failure mode, load–displacement curve and other mechanical property are studied. Many FEMs (fi nate element model) are established by ABAQUS software for comparative analysis under diff erent parameters. The FEM analysis results showed that the high-strength aluminum alloy ring-groove rivet connection is the pressure-bearing connection. Compared with the bolt connection, the high-strength aluminum alloy ring-groove rivet connection has good ductility, and the yield platform of the load–displacement curve is longer. The failure forms of high-strength aluminum alloy ring-groove rivet connection mainly include rivet shear failure, plate cross-section tearing and longitudinal section tearing failure. In order to avoid the above-mentioned damage, the recommended value of the edge distance is 2d 0 , and the end distance is recommended to take the value 2.5d 0 . Under the action of shear force, the stress stage of the high-strength aluminum alloy ring-groove rivet connection can be divided into four stages: friction, slippage, pressure bearing and strengthening; The shear and compressive bearing capacity of rivets under the two connection modes of single cover plate overlap and double cover plate butt joint is studied by changing the value of diff erent d/t ratio. Based on the relevant calculation formulas in the European aluminum alloy design code, the shear and compressive bearing capacity correction formulas suitable for the connection of domestic high-strength aluminum alloy rivets are derived. The research provides a reference basis for the ring-groove rivet connection of aluminum alloy nodes and improves the design specifi cations of aluminum alloy structures.

A Developed Transfer Matrix Method for Analysis of Elastic–Plastic Behavior of Structures

Jianpeng Sun,Kai Liu,Guangmeng Liu,Hui Li 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.5

The ductility of structure or component is particularly important when it encounters earthquake or other sudden disasters. It can reduce the damage of structure to a certain extent. The ductility mechanism of structure is closely related to the analysis of elastic–plastic behavior of structure. Therefore, an improved transfer matrix method based on elastic–plastic transfer element is proposed to analyze the elastic–plastic behavior of structures. The elastic–plastic element consists of two parts, elastic region and plastic region. According to the section stress analysis, the ratio of elastic zone to plastic zone can be determined to refl ect the elastic–plastic behavior. The analysis process is as follows: fi rstly, the elastic–plastic part of the structure is determined according to the mechanical behavior of the whole structure, then the elastic–plastic transfer unit is proposed according to the determined proportion of the elastic–plastic zone, and fi nally the mechanical behavior of the whole structure is analyzed. Through numerical examples, the correctness and eff ectiveness of the proposed method are verifi ed by comparing the analytical model with the theoretical solution. The results show that this method provides a new way for the further study of engineering structure mutation process.

Simulation Analysis on Seismic Performance of Assembled Composite Energy Dissipation Pipe Joint

Jianpeng Sun,Yingbiao Jiang,Guanjun Lv,Kai Liu,Ju Zhao 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.3

Based on the seismic ductility design concept, a kind of assembled composite energy dissipation pipe joint with rapid repair after the earthquake was proposed. We established the fi nite element models of assembled composite energy dissipation pipe joints with the 24 diff erent structural parameters, and carried out the low reversed cyclic loading simulation test. The strain cloud diagram, hysteretic curve, skeleton curve, stiff ness degradation curve and energy dissipation capacity curve of the pipe joints were obtained. The structural parameters’ infl uence on the performance indexes of the pipe joints was analyzed. The results show that the proposed assembled composite energy dissipation pipe joint has good ductility and energy dissipation capacity. The replacement of peripheral energy dissipation steel plate is simple and fast, and the mechanical properties can be restored after replacement. The diameter thickness ratio of peripheral energy dissipating steel pipe has more signifi cant impact on the seismic performance of the connecting parts. With the increase of the diameter thickness ratio of the peripheral energy dissipating steel pipe, the energy dissipation capacity gradually increases. The ratio of height to thickness has less eff ect on the seismic performance of the model, and the initial stiff ness and energy dissipation capacity of the model are signifi cantly enhanced after the stiff ened steel pipe is installed outside.

Parameter Sensitivity Study on Static and Dynamic Mechanical Properties of the Spatial Y-shaped Tied Arch Bridge

Jianpeng Sun,Zihan Tan,Jiaju Zhang,Wenwu Sun,Li Zhu 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.2

The spatial Y-shaped tied arch bridge is a rare form of innovative bridge on arch bridges around the world. It has important reference significance for the design and construction of bridge engineering worldwide. This arch bridge is novel in design and adopts single and double arch ribs combined structure. However, as a novel bridge type, its force situation is indetermination, so it is very important to study its mechanical properties and parameter sensitivity. In order to study the mechanical properties of the spatial Y-shaped tied arch bridge and the influence of structural parameters, this paper takes a spatial Y-shaped tied arch bridge under construction in China as the research object. The finite element software MIDAS Civil is used to establish the bridge model. The finite element model is used to analyze the static and dynamic performance of the spatial Y-shaped tied arch bridge under the use stage and the mechanical change trend under the influence of different rise-span ratios and double arch bifurcation angles. The results of single arch rib and double arch rib under constant load and live load are compared under different structural parameters in this paper, and the parameter sensitivity analysis of statics and dynamics is carried out. These analyses provide the adjustment basis and design reference for the design of the special-shaped arch bridge in the future.

Experimental and Numerical Simulation Study on Mechanical Properties of Shallow Slope Root-soil Composite in Qinghai Area

Yuan Sun,Hui Li,Zhifeng Cheng,Jianpeng Dong,Yawei Wang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.7

Natural disasters such as landslides often occur in Qinghai under the double deterioration ofearthquake and freeze-thaw cycles, ecological slope protection is an effective way to preventand control this type of disaster. In this paper, the mechanical properties of root-soilcomposites are investigated experimentally using triaxial apparatus and dynamic single shear(DSS) apparatus, and based on the discrete element method, a contact model more suitablefor reinforced soil materials is proposed to study the dynamic properties of root-soilcomposites under cyclic shear from a fine viewpoint. Based on the results of the study, thefollowing conclusions were drawn: 1) The presence of roots under the action of freeze-thawcycles increases the strength properties of the soil. At the same number of freeze-thaw cycles,the shear strength and cyclic resistance of the root-soil composites are higher than those of theloess. And the strength of the root-soil composites decreases with the increase of the numberof freeze-thaw cycles and then flattens out; 2) The proposed contact model can bettersimulate the softening effect of reinforced loess material under cyclic shear, which is moresuitable for simulating the mechanical behavior of loess and laying the foundation for furtherstudy of reinforced loess material from a fine viewpoint.; 3) The presence of the root systemwill improve the stability of the slope soil, and the root system will have a positive effect on theshear strength of the soil when the moisture content is within a certain range. The presence ofthe root system also increases the cyclic resistance of the soil. Under the same cyclic shearstress conditions, the number of damage cycles of the root-soil composites is higher than thatof the loess, the cumulative shear strain is less than that of the loess. However, the root systemno longer exerts positive effects under saturated conditions. The research results can providesome guidance for the construction of ecological slopes in loess areas, and provide a new wayto investigate the dynamic properties of root-soil composites from a fine viewpoint.