Seismic behavior of T-shaped steel reinforced high strength concrete short-limb shear walls under low cyclic reversed loading

Zongping Chen,Jinjun Xu,Yuliang Chen,Yisheng Su1 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.57 No.4

This paper presents an experimental study of six steel reinforced high strength concrete T-shaped short-limb shear walls configured with T-shaped steel truss under low cyclic reversed loading. Considering different categories of ratios of wall limb height to thickness, shear/span ratios, axial compression ratios and stirrup reinforcement ratios were selected to investigate the seismic behavior (strength, stiffness, energy dissipation capacity, ductility and deformation characteristics) of all the specimens. Two different failure modes were observed during the tests, including the flexural-shear failure for specimens with large shear/span ratio and the shear-diagonal compressive failure for specimens with small shear/span ratio. On the basis of requirement of Chinese seismic code, the deformation performance for all the specimens could not meet the level of ‘three’ fortification goals. Recommendations for improving the structural deformation capacity of T-shaped steel reinforced high strength concrete short-limb shear wall were proposed. Based on the experimental observations, the mechanical analysis models for concrete cracking strength and shear strength were derived using the equivalence principle and superposition theory, respectively. As a result, the proposed method in this paper was verified by the test results, and the experimental results agreed well with the proposed model.

Experimental Performance of Recycled Aggregate Concrete-filled Square Steel Tubular (RACSST) Stub Columns After Exposure to High Temperature and Water Spraying Cooling

Zhanjing Wu,Xiaojun Ke,Yisheng Su 한국강구조학회 2021 International Journal of Steel Structures Vol.21 No.3

In order to study the mechanical properties of Recycled Aggregate Concrete-fi lled Square Steel Tubular (RACFSST) stub columns after fi re exposure, a total of 37 specimens were exposed to heating temperatures and cooling phases (including natural cooling and water spray cooling), and the axial compression tests were subsequently conducted. The failure modes, axial load versus deformation curves, and residual bearing capacity of specimens with diff erent cooling methods were obtained. The results show that all specimens suff ered steel tube tearing and local buckling. The overall change law of the axial load versus displacement curves was signifi cantly aff ected by the heating temperature and cooling method, whereas not obviously aff ected by the replacement ratio of RCA. Compared with natural cooling, the residual bearing capacity of specimens decreased after water spray cooling, with a maximum decrease of 38.17%. A simplifi ed formula for calculating the residual bearing capacity which can take into account the infl uence of RAC ratio, heating temperature, and cooling method of reclaimed aggregate was proposed.

Physicochemical Characterization and an Injection Formulation Study of Water Insoluble ZCVI4-2, a Novel NO-Donor Anticancer Compound

Yuan Gao,Jianjun Zhang,Li Li,Feng Su,Zhenhua Gong,Yisheng Lai,Yihua Zhang 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.7

ZCVI4-2 was a novel nitric oxide-releasing glycosyl derivative of oleanolic acid that displayed strong cytotoxicity selectively against human hepatocellular carcinoma in vitro and in vivo. In this study, ZCVI4-2 was characterized by FT-IR spectroscopy, differential scanning calorimetry,powder X-ray diffractometry, Raman spectroscopy, hygroscopicity and stability. A high performance liquid chromatography method was also established for the quantitative determination of solubility and additional stability profile of ZCVI4-2. ZCVI4-2 was found to be an amorphous and stable solid with low solubility of less than 10 μg/mL. Based on the solubilization tests that included methods of cosolvency and micellization, the solution mixture of 5% Solutol HS-15, 5% 1, 2-propylene glycol and 5% anhydrous ethanol was determined to be the system for the preparation of the ZCVI4-2 early injection solution. The effect of pH, temperature, light and injectable isotonic glucose or NaCl solution on ZCVI4-2 injection was also investigated. Good stability was observed at all testing conditions. Under the conditions studied, the NO-releasing rate and amount of ZCVI4-2 from the early injection solution in rat plasma demonstrated a promising therapeutic efficacy while maintaining a good safety profile.

Performance and Calculations of Recycled Aggregate Concrete-filled Steel Tubular (RACFST) Short Columns under Axial Compression

Zongping Chen,Jinjun Xu,Jianyang Xue,Yisheng Su 한국강구조학회 2014 International Journal of Steel Structures Vol.14 No.1

This paper describes a series of tests on steel tubular short columns of circular section filled with normal concrete (NA) andrecycled aggregate concrete (RAC). Twenty-two specimens, including 11 small diameter of RAC-filled steel tubular (RACFST)columns named CA series and 11 larger diameter of RACFST columns called CB series, were tested to research the influenceof variations in confinement index and replacement ratio of recycled coarse aggregate (RCA), from 0% to 100% with 10%increasing. The test results show that both types of RACFST columns and normal concrete-filled steel tubular (CFST) columnsfailed due to oblique shear pressure damage with a drum-like. Comparisons are made with predicted bearing capacities ofRACFST columns using the existing theories, such as Unified Strengthen theory (I), Confinement theory (II) and Superpositiontheory (III). The equation for axial compression stress-strain curves of the whole process are proposed in this investigation forRACFST short columns, which can be directly used in theoretical and numerical analysis as well as practical engineering designand evaluation of RACFST structures.

Bond behaviors of shape steel embedded in recycled aggregate concrete and recycled aggregate concrete filled in steel tubes

Zongping Chen,Jinjun Xu,Ying Liang,Yisheng Su 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.17 No.6

Thirty one push-out tests were carried out in order to investigate the bond behavior between shape steel, steel tube (named steels) and recycled aggregate concrete (RAC), including 11 steel reinforced recycled aggregate concrete (SRRAC) columns, 10 recycled aggregate concrete-filled circular steel tube (RACFCST) columns and 10 recycled aggregate concrete-filled square steel tube (RACFSST) columns. Eleven recycled coarse aggregate (RCA) replacement ratios (i.e., 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%) were considered for SRRAC specimens, while five RCA replacement ratios (i.e., 0%, 25%, 50%, 75% and 100%), concrete type and length-diameter ratio for recycled aggregate concretefilled steel tube (RACFST) specimens were designed in this paper. Based on the test results, the influences of all variable parameters on the bond strength between steels and RAC were investigated. It was found that the load-slip curves at the loading end appeared the initial slip earlier than the curves at the free end. In addition, eight practical bond strength models were applied to make checking computations for all the specimens. The theoretical analytical model for interfacial bond shear transmission length in each type of steel-RAC composite columns was established through the mechanical derivation, which can be used to design and evaluate the performance of anchorage zones in steel-RAC composite structures.

Study on Restoring Force Model of RACFST Frame Infilled with RHB Masonry Wall

Ercong Meng,Yalin Yu,Yan Jiang,Shuoyu Liu,Yisheng Su 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.2

The establishment of a reasonable restoring force model is the basis for popularizing the application of the structure of recycled aggregate concrete fi lled steel tube (RACFST) frame infi lled with recycled hollow block (RHB) masonry wall. To achieve this goal, 2 specimens of RACFST frames infi lled with RHB masonry walls were designed under cyclic reversed load, and the hysteretic and skeleton curves were obtained. The results show that the hysteretic curves of specimens present plump spindle shape, meaning the structure has good energy dissipation ability. The working stages of specimens can be divided into four stages including integral elastic working stage of fi ller wall and frame, frame elastic working stage, elastic–plastic working stage and failure stage. Based on the parallel model of wall and frame, the calculation model for the inter-story bearing capacity, lateral stiff ness and unloading stiff ness of specimens were put forward respectively. Furthermore, the four polyline restoring force model for the structure was built, and it had good agreement with the experimental hysteretic curves.