Bearing Capacity of Stone-Lightweight Aggregate Concrete-Filled Steel Tubular Stub Column Subjected to Axial Compression

Xianggang Zhang,Xiaomei Kuang,Jianhui Yang,Yuhui Fan 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.7

The objective of this research was to investigate the axial compression performance of stone-lightweight aggregate concrete-filled steel tubular (hereafter referred to as SLCFST for simplicity) stub columns. Ten specimens, five circular SLCFST (C-SLCFST) stub columns and five square SLCFST (S-SLCFST) stub columns, were tested using replacement ratios of normal gravel aggregate of between 0% and 100%, in increments of 25%. The influence of replacement ratio on axial compression performance and failure mode, ultimate bearing capacities and peak displacements was analysed. The results were compared, and show that under axial compression loading, strength damage occurs in SLCFST stub columns. The working process of SLCFST stub columns can be divided into four parts: an elastic stage, an elastic-plastic stage, a gentle descent stage and a plastic stage. The ultimate bearing capacities of the specimens were calculated and analysed based on existing design codes. By introducing the influence parameter of normal gravel replacement ratio, mathematical models for predicting the complete stress-strain compression curves of C-SLCFST and S-SLCFST stub columns were developed and verified.

Axial compression performance of basalt-fiber-reinforced recycled-concrete-filled square steel tubular stub column

Zhang, Xianggang,Gao, Xiang,Wang, Xingguo,Meng, Ercong,Wang, Fang Techno-Press 2020 Advances in concrete construction Vol.10 No.6

This study aimed to inspect the axial compression mechanical performance of basalt-fiber-reinforced recycled - concrete (BFRRC)-filled square steel tubular stub column. The replacement ratio of recycled coarse aggregate (RCA) and the basalt fiber (BF) dosage were used as variation parameters, and the axial compression performance tests of 15 BFRRC-filled square steel tubular stub column specimens were conducted. The failure mode and the load-displacement/strain curve of the specimen were measured. The working process of the BFRRC-filled square steel tubular stub column was divided into three stages, namely, elastic-elastoplasticity, sudden drawdown, and plasticity. The influence of the design parameters on the peak bearing capacity, energy dissipation performance, and other axial compression performance indexes was discussed. A mathematical model of segmental stiffness degradation was proposed on the basis of the degradation law of combined secant-stiffness under axial compression. The full-process curve equation of axial compressive stress-strain was proposed by introducing the influencing factors, including the RCA replacement ratio and the BF dosage, and the calculated curve agreed well with the test-measured curve.

Experimental and finite element analyses of eccentric compression of basalt-fiber reinforced recycled aggregate concrete-filled circular steel tubular stub column

Xianggang Zhang,Songpeng Zhang,Junna Yang,Xu Chen,Gaoqiang Zhou 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.42 No.5

To study the eccentric compressive performance of the basalt-fiber reinforced recycled aggregate concrete (BFRRAC)-filled circular steel tubular stub column, 8 specimens with different replacement ratios of recycled coarse aggregate (RCA), basalt fiber (BF) dosage, strength grade of recycled aggregate concrete (RAC) and eccentricity were tested under eccentric static loading. The failure mode of the specimens was observed, and the relationship curves during the entire loading process were obtained. Further, the load-lateral displacement curve was simulated and verified. The influence of the different parameters on the peak bearing capacity of the specimens was analyzed, and the finite element analysis model was established under eccentric compression. Further, the design-calculation method of the eccentric bearing capacity for the specimens was suggested. It was observed that the strength failure is the ultimate point during the eccentric compression of the BFRRAC-filled circular steel tubular stub column. The shape of the load-lateral deflection curves of all specimens was similar. After the peak load was reached, the lateral deflection in the column was rapidly increased. The peak bearing capacity decreased on enhancing the replacement ratio or eccentric distance, while the core RAC strength exhibited the opposite behavior. The ultimate bearing capacity of the BFRRAC-filled circular steel tubular stub column under eccentric compression calculated based on the limit analysis theory was in good agreement with the experimental values. Further, the finite element model of the eccentric compression of the BFRRAC-filled circular steel tubular stub column could effectively analyze the eccentric mechanical properties.

Mechanical performance of sand-lightweight concrete-filled steel tube stub column under axial compression

Xianggang Zhang,Dapeng Deng,Xinyan Lin,Jianhui Yang,Lei Fu 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.6

In order to study the axial compression performance of sand-lightweight concrete-filled steel tube (SLCFST) stub columns, three circular SLCFST (C-SLCFST) stub column specimens and three SLCFST square (S-SLCFST) stub column specimens were fabricated and static monotonic axial compression performance testing was carried out, using the volume ratio between river sand and ceramic sand in sand-lightweight concrete (SLC) as a varying parameter. The stress process and failure mode of the specimens were observed, stress-strain curves were obtained and analysed for the specimens, and the ultimate bearing capacity of SLCFST stub column specimens was calculated based on unified strength theory, limit equilibrium theory and superposition theory. The results show that the outer steel tubes of SLCFST stub columns buckled outward, core SLC was crushed, and the damage to the upper parts of the S-SLCFST stub columns was more serious than for C-SLCFST stub columns. Three stages can be identified in the stress-strain curves of SLCFST stub columns: an elastic stage, an elastic-plastic stage and a plastic stage. It is suggested that AIJ-1997, CECS 159:2004 or AIJ-1997, based on superposition theory, can be used to design the ultimate bearing capacity under axial compression for C-SLCFST and S-SLCFST stub columns; for varying replacement ratios of natural river sand, the calculated stress-strain curves for SLCFST stub columns under axial compression show good fitting to the test measure curves.

Flexural Behavior of RC Beams with NSM Prestressed Helical Rib Steel Wire

Meixiang Zhang,Xiaolin Yang,Yahong Ding,Ping Xu,Bo Sun,Xiaoyi Zhang,Xianggang Zhang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.9

The reinforcement technique of near-surface mounted?NSM?prestressed helical rib steel wire (PHRSW) with wide raw material sources, lower in price and high application value can significantly enhance the flexural behavior of reinforced-concrete (RC) structures. Based on 8 flexural RC beams reinforced with NSM PHRSW, performance of test beams under different groove widths (10 mm, 15 mm and 20 mm) and concrete strengths (C30 and C40) was analyzed, including load-deflection, ductility, flexural capacity, strain of longitudinal steel bar and HRSW, failure mode and crack propagation. The results show that the overall flexural behavior RC beams reinforced with NSM PHRSW was significantly improved. There is a good entirety bearing capacity between the longitudinal reinforcement and PHRSW of reinforced beam with suitable groove size. The comprehensive performance of reinforced beams increases first then decreases, with the increase of groove size. The higher the strength of concrete, the more significant the influence of groove size. There is an optimal match between groove width and concrete strength for RC beams reinforced with NSM PHRSW. Considering comprehensive property of reinforced beams, groove width with 15mmwas best in this research. The results can make the research of RC beams reinforced with NSM PHRSW more comprehensive and in-depth, and provide design basis for its engineering application.