Owing to commercial or aesthetic considerations, the shapes of high-rise city buildings are becoming increasingly unique and complicated. This brings challenges to structural engineers in analyzing and predicting their dynamic responses, which are crucial to the safety of the buildings. For these buildings in China, a detailed study, sometimes including shaking table testing, is required to verify the safety and rationality of their design. This paper presents results of a study performed for a high-rise building with a large space in the ground floor and large openings in elevation. The maximum responses of acceleration and deformation were measured and evaluated, as well as the dynamic characteristics, cracking pattern and failure mechanism of the building. In addition, a 3D finite element analysis was carried out and the analytical results were compared with experimental ones to gain a better understanding of the structural behavior. Suggestions regarding the design of this type of structure were also derived from the test results.

Though extensive research has been carried out for the ultimate strength of steel reinforced concrete(SRC) members under static and cyclic load, there was only limited information on the applied analysis models. Modeling of the inelastic response of SRC members can be accomplished by using a microcosmic model. However, generally used microcosmic model, which usually contains a group of parameters, is too complicated to apply in the nonlinear structural computation for large whole buildings. The intent of this paper is to develop an effective modeling approach for the reliable prediction of the inelastic response of SRC columns. Firstly, five SRC columns were tested under cyclic static load and constant axial force. Based on the experimental results, normalized trilinear skeleton curves were then put forward. Theoretical equation of normalizing point (ultimate strength point) was built up according to the load-bearing mechanism of RC columns and verified by the 5 specimens in this test and 14 SRC columns from parallel tests. Since no obvious strength deterioration and pinch effect were observed from the load-displacement curve, hysteresis rule considering only stiffness degradation was proposed through regression analysis. Compared with the experimental results, the applied analysis model is so reasonable to capture the overall cyclic response of SRC columns that it can be easily used in both static and dynamic analysis of the whole SRC structural systems.

This paper presents a comprehensive investigation on viscous wall dampers (VWD) used for seismic response mitigation of reinforced concrete (RC) frames. First, a shaking table test on a large-scaled three-story RC frame with VWD and another identical three-story RC frame without any dampers was carried out. A total of three types of earthquake excitations were inputted to the shaking table to evaluate the effects of VWD on seismic response mitigation. The influence of different earthquake input intensities on seismic performance of VWD were also examined. From the experiment, this paper further assessed the performance of VWD on seismic retrofitting of a partly damaged RC frame. The test results show that the main effect of installing VWD is to provide a large amount of supplemental damping to the RC frame, and at the same time the stiffness of the structure is also raised moderately as an accessorial effect. As a result, the displacement responses of the RC frame can always be reduced significantly, while the acceleration responses and the base shear of the RC frame were reduced in some test cases, but increased in other cases. The test results of seismic retrofit also show that seismic responses of the damaged RC frame can be alleviated evidently by the installation of VWD and, therefore, installing VWD is an effective retrofitting approach for RC frames. After test investigation, elastic and inelastic seismic responses of the RC frame were numerically simulated using finite element software Sap2000 and Canny99, respectively. A good agreement of experimental results and analysis results verified the analytical method and model used for RC structures with VWD.

Composite members and hybrid systems are to be widely used in the high-rise buildings to make full use of structural steel and concrete. By employing the steel reinforced concrete (SRC) wall system, structural engineers expect to obtain the increase of stiffness, strength, ductility and fire resistance capacity; the compact cross-section of high-rise systems; and the reduction of construction cost and time. Due to the deficiencies in the present codes and in the research base, however, better rules for determining shear carrying capacity of SRC walls are needed. This paper is focusing on the tests and formulations of SRC coupled walls (SCW) and SRC tubes (ST). Three 1/5 scaled specimens of SCW were tested under cyclic loading and constant axial force, while three ST specimens were subjected to reversed loading without axial force. These specimens were measured with the time history and observed failing in shear. The formulae of ultimate shear strength of SCW and ST were then established on the basis of the shear-bearing mechanism analysis of RC structural walls. Predictions of shear strength from the proposed method are compared with experimental results. Taking the safety margin of the design into consideration, formulae of SRC walls proposed here are suitable for the implementation in a code of practice.

In China, the irregular high-rise buildings are beconung more extensive. Considering the irregularities and complexities of these buildings, it is significant to verify the safety and rationality of their seismic design through effective means including small scale dynamic model tests, refined numerical analysis and large scale joint tests. The target building of this paper is Shanghai International Design Center (SHIDC), which has two different-height connected towers designed by Japanese Architect Tadao Ando. The hybrid system of reinforced concrete core walls in conjunction with perimeter steel frames is out of Chinese code in the plan and elevation layouts. Thus, scaled model was carefully tested on the shaking table to obtain the weak position, dynamic characteristics, inter-story drift, and shear force of the structure. A linear dynamic analysis by ETABS was performed to compare, check, and support the experimental results. On the basis of those results, the seismic performance of the complex irregular structure was evaluated and the suggestions to the same type of structural design were given.