Experimental study on seismic performance of partial penetration welded steel beam-column connections with different fillet radii

Hanbin Ge,Liang-Jiu Jia,Lan Kang,Toshimitsu Suzuki 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.17 No.6

Full penetration welded steel moment-resisting frame (SMRF) structures with welded box sections are widely employed in steel bridges, where a large number of steel bridges have been in operation for over fifty years in Japan. Welding defects such as incomplete penetration at the beam-column connections of these existing SMRF steel bridge piers were observed during inspection. Previous experiments conducted by the authors' team indicate that gusset stiffeners (termed fillets in this study) at the beam-web-to-column-web joint of the beam-column connections may play an important role on the seismic performance of the connections. This paper aims to experimentally study the effect of the fillet radius on seismic performance of the connections with large welding defects. Four specimens with different sizes of fillet radii were loaded under quasi-static incremental cyclic loading, where different load-displacement relations and cracking behaviors were observed. The experimental results show that, as the size of the fillet radius increases, the seismic performance of the connections can be greatly improved.

Load-carrying capacity degradation of reinforced concrete piers due to corrosion of wrapped steel plates

Hanbin Ge,Shengbin Gao,Toyoki Ikai,Jie Ni 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.1

Two-dimensional elastoplastic finite element formulation is employed to investigate the load- carrying capacity degradation of reinforced concrete piers wrapped with steel plates due to occurrence of corrosion at the pier base. By comparing with experimental results, the employed finite element analysis method is verified to be accurate. After that, a series of parametric studies are conducted to investigate the effect of corrosion ratio and corrosion mode of steel plates located near the base of in-service pier P2 on load-carrying capacity of the piers. It is observed that the load-carrying capacity of the piers decreases with the increase in corrosion ratio of steel plates. There exists an obvious linear relationship between the load-carrying capacity and the corrosion ratio in the case of even corrosion mode. The degradation of load-carrying capacity resulted from the web's uneven corrosion mode is more serious than that under even corrosion mode, and the former case is more liable to occur than the latter case in actual engineering application. Finally, the failure modes of the piers under different corrosion state are discussed. It is found that the principal tensile strain of concrete and yield range of steel plates are distributed within a wide range in the case of slight corrosion, and they are concentrated on the column base when complete corrosion occurs. The findings obtained from the present study can provide a useful reference for the maintenance and strengthening of the in-service piers.

Experimental study on ductile crack initiation in compact section steel columns

Xiaoqun Luo,Hanbin Ge,Masatoshi Ohashi 국제구조공학회 2012 Steel and Composite Structures, An International J Vol.13 No.4

In order to develop a verification method for extremely low cycle fatigue (ELCF) of steel structures, the initiation mechanism of ductile cracks is investigated in the present study, which is the first step of brittle fracture, occurred in steel bridge piers with thick-walled sections. For this purpose, a total of six steel columns with small width-thickness ratios were tested under cyclic loading. It is found that ductile cracks occurred at the column base in all the specimens regardless of cyclic loading histories subjected. Moreover, strain history near the crack initiation location is illustrated and an index of energy dissipation amount is proposed to evaluate deformation capacity of structures.

Behavior of a steel bridge with large caisson foundations under earthquake and tsunami actions

Lan Kang,Hanbin Ge,Kazuya Magoshi,Tetsuya Nonaka 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.31 No.6

The main focus of this study is to numerically investigate the influence of strong earthquake and tsunami-induced wave impact on the response and behavior of a cable-stayed steel bridge with large caisson foundations, by assuming that the earthquake and the tsunami come from the same fault motion. For this purpose, a series of numerical simulations were carried out. First of all, the tsunami-induced flow speed, direction and tsunami height were determined by conducting a twodimensional (2D) tsunami propagation analysis in a large area, and then these parameters obtained from tsunami propagation analysis were employed in a detailed three-dimensional (3D) fluid analysis to obtain tsunami-induced wave impact force. Furthermore, a fiber model, which is commonly used in the seismic analysis of steel bridge structures, was adopted considering material and geometric nonlinearity. The residual stresses induced by the earthquake were applied into the numerical model during the following finite element analysis as the initial stress state, in which the acquired tsunami forces were input to a whole bridge system. Based on the analytical results, it can be seen that the foundation sliding was not observed although the caisson foundation came floating slightly, and the damage arising during the earthquake did not expand when the tsunami-induced wave impact is applied to the steel bridge. It is concluded that the influence of tsunami-induced wave force is relatively small for such steel bridge with large caisson foundations. Besides, a numerical procedure is proposed for quantitatively estimating the accumulative damage induced by the earthquake and the tsunami in the whole bridge system with large caisson foundations.

Predicting seismic performance of locally corroded steel box-section piers

Shengbin Gao,Yi Pang,Hanbin Ge 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.5

This paper aims to propose a simplified method for predicting ultimate strength and ductility behavior of locally corroded steel box-section bridge piers. Firstly, the accuracy of the proposed 3-D elastoplastic finite element model for the steel piers subjected to a constant vertical load and cyclic lateral loading is verified by comparing the analytical results with test results. Then, a series of parametric study is carried out to investigate the effect of corrosion height ratio and corrosion thickness ratio of steel plates on the ultimate strength and ductility behavior of these piers. Finally, by establishing 2-D beam-column element models and comparing the calculation results with those of the 3-D models, correction coefficients for the ductility ratio and ultimate strength of 2-D beam-column element model under local corrosion are proposed. The research results indicate that there exists a most unfavorable corrosion height which makes the ductility ratio of steel piers the smallest. The ultimate strength of the steel piers will not have a distinct degradation when the corrosion height becomes larger than 0.5Ld. The correction coefficient formula for ductility ratio with respect to different aspect ratio of steel piers, and the linear relationship between correction strength coefficient and the corrosion thickness ratio are proposed. Correction coefficients for 2-D beam-column element model under the most unfavorable corrosion height are proven to have a rational accuracy, which provides a fast and simplified method to evaluate the ultimate strength and ductility behavior of such steel piers under local corrosion.

Brace-type shear fuses for seismic control of long-span three-tower self-anchored suspension bridge

Feifei Shao,Liangjiu Jia,Hanbin Ge 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.81 No.2

The Brace-Type Shear Fuse (BSF) device is a newly proposed steel damper with excellent cumulative ductility and stable energy dissipation. In consideration of the current situation where there are not many alternatives for transversal seismic devices used in long-span three-tower self-anchored bridges (TSSBs), this paper implements improved BSFs into the world’s longest TSSB, named Jinan Fenghuang Yellow River Bridge. The new details of the BSF are developed for the TSSB, and the force-displacement hysteretic curves of the BSFs are obtained using finite element (FE) simulations. A three-dimensional refined finite element model for the research TSSB was established in SAP2000, and the effects of BSFs on dynamic characteristics and seismic response of the TSSB under different site conditions were investigated by the numerical simulation method. The results show that remarkable controlling effects of BSFs on seismic response of TSSBs under different site conditions were obtained. Compared with the case without BSFs, the TSSB installed with BSFs has mitigation ratios of the tower top displacement, lateral girder displacement, tower bending moment and tower shear force exceeding 95%, 78%, 330% and 346%, respectively. Meanwhile, BSFs have a sufficient restoring force mechanism with a minor post-earthquake residual displacement. The proposed BSFs exhibit good application prospects in long-span TSSBs.

A study on application of high strength steel SM570 in bridge piers with stiffened box section under cyclic loading

Lan Kang,Motoya Suzuki,Hanbin Ge 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.26 No.5

Although a lot of experimental and analytical investigations have been carried out for steel bridge piers made of SS400 and SM490, the formulas available for SS400 and SM490 are not suitable for evaluating ultimate load and deformation capacities of steel bridge piers made of high strength steel (HSS) SM570. The effect of various parameters is investigated in this paper, including plate width-to-thickness ratio, column slenderness ratio and axial compression force ratio, on the ultimate load and deformation capacities of steel bridge box piers made of SM570 steel subjected to cyclic loading. The elasto-plastic behavior of the steel bridge piers under cyclic loads is simulated through plastic large deformation finite element analysis, in which a modified two-surface model (M2SM) including cyclic hardening is employed to trace the material nonlinearity. An extensive parametric study is conducted to study the influences of structural parameters on the ultimate load and deformation capacities. Based on these analytical investigations, new formulas for predicting ultimate load and deformation capacities of steel bridge piers made of SM570 are proposed. This study extends the ultimate load and deformation capacities evaluation of steel bridge piers from SS400, SM490 steels to SM570 steel, and provides some useful suggestions.

Effect of post weld treatment on cracking behaviors of beam-column connections in steel bridge piers

Liang-Jiu Jia,Hanbin Ge,Toshimitsu Suzuki 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.17 No.5

A great number of moment-resisting steel structures collapsed due to ductile crack initiation at welded beam-column connections, followed by explosive brittle fracture in the Kobe (Hyogoken-Nanbu) earthquake in 1995. A series of experimental and numerical studies on cracking behaviors of beam-column connections in steel bridge piers were carried out by the authors’ team. This paper aims to study the effect of post weld treatment on cracking behaviors of the connections during a strong earthquake event. Experiments of three specimens with different weld finishes, i.e., as-welded, R-finish, and burr grinding, were conducted. The experimental results indicate that the instants of ductile crack initiation are greatly delayed for the specimens with R-finish and burr grinding finishes compared with the as-welded one. The strain concentration effect in the connection is also greatly reduced in the specimens with post weld treatment compared with the as-welded one, which was also verified in the tests.

Confinement evaluation of concrete-filled box-shaped steel columns

K.A.S. Susantha,Hanbin Ge,Tsutomu Usami 국제구조공학회 2001 Steel and Composite Structures, An International J Vol.1 No.3

This paper presents a three-dimensional finite element analysis methodology for a quantitative evaluation of confinement in concrete-filled box-shaped unstiffened steel columns. The confinement effects of concrete in non-circular sections can be assessed in terms of maximum average lateral pressure. A brief review of a previous method adopted for the same purpose is also presented. The previous method is based on a two-dimensional finite element analysis method involving a concrete-steel interaction model. In both the present and previous methods, average lateral pressure on concrete is computed by means of the interaction forces present at the concrete-steel interface. Subsequently, the strength enhancement of confined concrete is empirically related to the maximum average lateral pressure. The results of the former and latter methods are then compared. It is found that the results of both methods are compatible in terms of confined concrete strengths, although the interaction model yields a somewhat overestimated estimation of confinement than those of the present method when relatively high strength concrete is used. Furthermore, the confinement in rectangular-shaped sections is investigated and the reliability of previously adopted simplifications in such cases is discussed.

Ductile crack initiation evaluation in stiffened steel bridge piers under cyclic loading

Wataru Fujie,Miki Taguchi,Lan Kang,Hanbin Ge,Bin Xu 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.36 No.4

Although detailed shell analysis is suitable to predict the ductile crack initiation life of steel members, such detailed method adds time expense and complexity. In order to simply predict the ductile crack initiation life of stiffened steel bridge piers, a total of 33 cases are simulated to carry out the parametric analyses. In the analysis, the effects of the width-to-thickness ratio, slenderness ratio, plate thickness and so on are considered. Both shell analyses and beam analyses about these 33 cases are conducted. The plastic strain and damage index obtained from shell and beam analyses are compared. The modified factor βs is determined based on the predicted results obtained from both shell and beam analyses in order to simulate the strain concentration at the base corner of the steel bridge piers. Finally, three experimental results are employed to verify the validity of the proposed method in this study.