Theoretical Study on the Influence of Welding Collar on the Shear Behavior of Stud Shear Connectors

Yulin Zhan,Siji Lu,Yuanbiao Zheng,Haijun Jiang,Shaohui Xiong 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.4

Arc stud welding will melt the root of the stud to form a welding collar. For the purpose of exploring the influence of welding collar, numerical method is adopted for the theoretical analysis on shear resistance of the stud under several groups of different welding collar parameters. Firstly, the shear resistance between whether the headed studs considering the welding collars or not is compared. Then, the radius and height parameters of welding collar are changed. Finally, the increment ratio of bearing capacity by welding collars with the same height-diameter ratio is taken into consideration. Experimental data from three push-out test are adopted to validate the accuracy of the numerical method. The results show that the welding collar changes the yield area at the bottom of the stud. The height parameter has less influence than the radius. Under the condition that welding collars have the same height-diameter ratio, the improvement of shear resistance with different diameters roughly converges to 7.28%. The formulas of various countries show that at the height-diameter ratio of 0.25, the average value of bearing capacity of welding collar in various specification approach 7.1% of formula value.

Comparison of long-term behavior between prestressed concrete and corrugated steel web bridges

Yulin Zhan,Fang Liu,Zhongguo John Ma,Zhiqiang Zhang,Zengqiang Duan,Ruinian Song 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.30 No.6

Prestressed concrete (PC) bridges using corrugated steel webbing have emerged as one of the most promising forms of steel-concrete composite bridge. However, their long-term behavior is not well understood, especially in the case of largespan bridges. In order to study the time-dependent performance, a large three-span PC bridge with corrugated steel webbing was compared to a similar conventional PC bridge to examine their respective time-dependent characteristics. In addition, a threedimensional finite element method with step-by-step time integration that takes into account cantilever construction procedures was used to predict long-term behaviors such as deflection, stress distribution and prestressing loss. These predictions were based upon four well-established empirical creep prediction models. PC bridges with a corrugated steel web were observed to have a better long-term performance relative to conventional PC bridges. In particular, it is noted that the pre-cambering for PC bridges with a corrugated steel web could be smaller than that of conventional PC bridges. The ratio of side-to-mid span has great influence on the long-term deformation of PC bridges with a corrugated steel web, and it is suggested that the design value should be between 0.4 and 0.6. However, the different creep prediction models still showed a weak homogeneity, thus, the further experimental research and the development of health monitoring systems are required to further progress our understanding of the long-term behavior of PC bridges with corrugated steel webbing.

Failure Mode of Orthotropic Two-way Composite Slab under Concentrated Load

Yulin Zhan,Wenfeng Huang,Yu Qiao,Zhouyuan Xu,Renda Zhao 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.12

Ordinary reinforced concrete two-way slabs generally suffer from punching failure under concentrated loads, which is a brittle failure and unfavorable to the structures. The composite slabs with steel sheets and PBL (perfobond rib) shear connectors have been applied for reducing the damage to bridge decks from vehicles. Although it is widely used on bridges, the failure mode of the orthotropic two-way composite slabs has rarely been studied when subject to concentrated loads. Accordingly, static loading tests with concentrated forward central load was carried out on 4 two-way composite slabs, in which the effects of the thickness of steel bottom sheets and concrete plates and spacing of PBL shear connectors on mechanical properties were investigated. The test results show that about 12% of the ultimate bearing capacity decreases when the perfobond ribs are spaced farther apart from 180 mm to 240 mm or the thickness of steel bottom sheets is reduced from 10 mm to 8 mm. And the bearing capacity drops by 38.2% when the thickness of concrete plates decreases by 30 mm. The steel-concrete composite slabs exhibit clear bidirectional force characteristics during the loading process, with the main forced direction being along the perfobond ribs, which is related to the stiffness ratio of the two directions. The two-way composite slabs have high bearing capacity and ductility, with obvious signs before failure. The specimens continue to bear the load after local punching failure of concrete near the loading point, which shows the features of both bending and punching failure. Based on the test results, a bending punching failure mode is proposed, which provides a new approach for the calculation of ultimate bearing capacity. An analytical calculation method for ultimate bearing capacity of orthotropic two-way composite slabs based on the failure mode above is derived with yield line theory and plastic theory, which is in excellent agreement with the tested results.

The fabrication of tungsten oxide layers on pure Al substrate by plasma electrolytic oxidation in sodium tungstate based electrolytes

Tingyan Zhan,Wenbin Tu,Yulin Cheng,Junxiang Han,Bin Su,Yingliang Cheng 한국표면공학회 2017 한국표면공학회 학술발표회 초록집 Vol.2017 No.11

Seismic Vulnerability Analysis of Multi-main-span High Pier Continuous Rigid-frame Bridge in Terms of Cloud Method

Jingang Zhao,Hongyu Jia,Yulin Zhan 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.6

Due to the complex canyon topography in southwestern regions of China, several multi-main-span high pier continuous rigid-frame bridges (MHPCRFBs) are built to meet the special terrain. Owing to the great effect of high-order modes, the seismic responses of MHPCRFBs are more complicated than the conventional signal main span continuous rigid-frame bridges. However, there has been very limited researches focus on the seismic vulnerability of MHPCRFBs. This study selects a practical five-span (three main span) high pier continuous rigid-frame bridge as a study object to investigate the seismic vulnerability of MHPCRFBs under near-field pulse-like seismic wave excitation. And a finite element model of the example bridge is built by OpenSees incorporating the influence of abutment, and simultaneously100 near-field pulse-like seismic waves are chosen to research their effect on the seismic vulnerability of the MHPCRFB. The dynamic nonlinear time-history analyses are carried out to record the peak demand values of the example bridge under three seismic excitation calculation cases (longitudinal earthquake, biaxial earthquake, and triaxial earthquake). Thirty-three intensity measures are compared with respect to two statistical parameters including correlation efficient and root mean square error, the peak ground velocity (PGV) turns out to be the optimal intensity measure for seismic vulnerability analysis of MHPCRFB. Subsequently, by using the analysis procedures of the cloud method, the seismic vulnerability curves of MHPCRFB are developed and compared. The results of this study show that the bottom and top areas of the high piers are more fragile at the slight and moderate damage stages along longitudinal direction, and only the bottom areas are prone to damage along transverse direction. And the seismic wave excitation directions have an obvious influence on the seismic damage probability of the MHPCRFB. In addition, the zone with larger failure probabilities of the lower pier is significantly longer than the higher pier. The obtained results provide helpful reference for the seismic-resistant design and consolidation of MHPCRFBs, shed light on the lower pier of MHPCRFBs should be paid high concern to the anti-seismic design.

Interfacial behavior of segmental concrete-filled Basalt FRP tube under cyclic loading

Yuehan Sun,Kailai Deng,Yulin Zhan,Wenfeng Huang,Chao Yin 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.1

A segmental concrete-filled basalt fiber-reinforced polymer (BFRP) tube was proposed, whose lightweight characteristic promoted convenient bridge column transportation and construction. A special connecting component between the adjacent BFRP segments ensured effective transfer of sectional forces. Four specimens, including three segmental specimens and one comparative integral concrete-filled BFRP tube, were tested to investigate the mechanical performance of the BFRP tube under cyclic loading. Damage patterns, load-deformation response, and strain development were observed, showing that the segmental concrete-filled BFRP tube presented satisfactory load-carrying and deformation capacities. Further, the connecting component effectively guaranteed a satisfactory hysteretic performance. Based on the test results, the overall load-carrying capacity was mainly determined by the moment resistance of the interface. Furthermore, the segmental structure weakened the confining effect on the core concrete, though applying multiple stirrups could compensate for the reduced confining effect. Finally, design methods were proposed for the connecting component.

Nonlinear finite element analysis of circular concrete-filled steel tube structures

Tengfei Xu,Tianyu Xiang,Renda Zhao,Yulin Zhan 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.3

The structural behaviors of circular concrete filled steel tube (CFT) structures are investigated by nonlinear finite element method. An efficient three-dimensional (3D) degenerated beam element is adopted. Based on those previous studies, a modified stress-strain relationship for confined concrete which introduces the influence of eccentricity on confining stress is presented. Updated Lagrange formulation is used to consider the geometrical nonlinearity induced by large deformation effect. The nonlinear behaviors of CFT structures are investigated, and the accuracy of the proposed constitutive model for confined concrete is mainly concerned. The results demonstrate that the confining effect in CFT elements subjected to combining action of axial force and bending moment is far sophisticated than that in axial loaded columns, and an appropriate evaluation about this effect may be important for nonlinear numerical simulation of CFT structures.

Nonlinear finite element analysis of circular concrete-filled steel tube structures

Xu, Tengfei,Xiang, Tianyu,Zhao, Renda,Zhan, Yulin Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.3

The structural behaviors of circular concrete filled steel tube (CFT) structures are investigated by nonlinear finite element method. An efficient three-dimensional (3D) degenerated beam element is adopted. Based on those previous studies, a modified stress-strain relationship for confined concrete which introduces the influence of eccentricity on confining stress is presented. Updated Lagrange formulation is used to consider the geometrical nonlinearity induced by large deformation effect. The nonlinear behaviors of CFT structures are investigated, and the accuracy of the proposed constitutive model for confined concrete is mainly concerned. The results demonstrate that the confining effect in CFT elements subjected to combining action of axial force and bending moment is far sophisticated than that in axial loaded columns, and an appropriate evaluation about this effect may be important for nonlinear numerical simulation of CFT structures.