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Recent progress of seismic research on tall buildings in China Mainland

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Earthquake eng.neering and eng.neering Vibration 2014年第S1期13卷 47-61页

作者： Lu Xilin Jiang Huanjun state key laboratory of disaster reduction in civil eng.neering Tongji University

As a result of rapid economic growth and urbanization in the past two decades,many tall buildings have been constructed in China Mainland,offering researchers and practitioners an excellent opportunity for research and practice in the field of structural eng.neering. This paper reviews progress by researchers throughout China Mainland on the seismic research of tall buildings,focusing on three major topics that impact the seismic performance of tall buildings. These are:(1) new types of steel-concrete composite structural members such as steel-concrete composite shear walls and columns,(2) earthquake resilient shear wall structures such as shear walls with replaceable structural components,self-centering shear walls and rocking walls,and(3) performance-based seismic design,including seismic performance index,performance level and design method. The paper concludes by presenting future research needs and directions in this field.

关键词： tall buildings steel-concrete composite member earthquake resilient structure performance-based seismic design

An alternative practical design method for structures with viscoelastic dampers

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Earthquake eng.neering and eng.neering Vibration 2018年第3期17卷 459-473页

作者： Joaquim Mimusse Tchamo Zhou Ying state key laboratory of disaster reduction in civil eng.neering Tongji University

Viscoelastic dampers（VEDs） are one of the most common passive control devices used in new and retrofit building projects which reduce the structure responses and dissipate seismic energy during an *** methods to design this kind of dampers have been proposed based on the desired level of additional damping,eigenvalue assignment,modal strain energy,linear quadratic regulator control theories,and other *** the current eng.neering practice,the popular method is the one based on the modal strain energy that uses the inter-story lateral stiffness as one of the main variables for damper ***,depending on the configuration of the structure,in some cases the resulting interstory lateral stiffness can be very ***,the dampers size would also be large producing much more damping than that effectively necessary,resulting in an increase of the overall cost of the supplemental damping system and causing excessive stress on the structural elements connected to the *** this paper an alternative practical design method for structures with VEDs is *** method uses the inter-story shear forces as one of the main variables to accomplish the damper design compared to what was done in previous *** time-history analyses were conducted on a 7-story reinforced concrete（RC） structure to check the reliability and effectiveness of the proposed *** on the seismic performance between the structure without dampers and that equipped with VEDs were carried *** is concluded that the proposed method results in a very suitable size of dampers,which are able to improve the performance of the structure at all levels of earthquake ground motions and satisfying the drift requirement prescribed in the codes.

关键词： viscoelastic dampers passive control seismic design method inter-story shear forces earthquake eng.neering

Shake-table testing of a self-centering precast reinforced concrete frame with shear walls

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Earthquake eng.neering and eng.neering Vibration 2018年第2期17卷 221-233页

作者： Lu Xilin Yang Boya Zhao Bin state key laboratory of disaster reduction in civil eng.neering Tongji University

The seismic performance of a self-centering precast reinforced concrete （RC） frame with shear walls was investigated in this paper. The lateral force resistance was provided by self-centering precast RC shear walls （SPCW）, which utilize a combination ofunbonded prestressed post-tensioned （PT） tendons and mild steel reinforcing bars for flexural resistance across base joints. The structures concentrated deformations at the bottom joints and the unbonded PT tendons provided the self-centering restoring force. A 1/3-scale model of a five-story self-centering RC frame with shear walls was designed and tested on a shake-table under a series of bi-directional earthquake excitations with increasing intensity. The acceleration response, roof displacement, inter-story drifts, residual drifts, shear force ratios, hysteresis curves, and local behaviour of the test specimen were analysed and evaluated. The results demonstrated that seismic performance of the test specimen was satisfactory in the plane of the shear wall; however, the structure sustained inter-story drift levels up to 2.45%. Negligible residual drifts were recorded after all applied earthquake excitations. Based on the shake-table test results, it is feasible to apply and popularize a self-centering precast RC frame with shear walls as a structural system in seismic regions.

关键词： self-centering shake-table test RC frame with shear walls precast unbonded post-tensioning seismicperformance

Seismic performance of cable-sliding friction bearing system for isolated bridges

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Earthquake eng.neering and eng.neering Vibration 2012年第2期11卷 173-183页

作者： Cheung Pakchiu state key laboratory of disaster reduction in civil eng.neering Tongji University

During past strong earthquakes, highway bridges have sustained severe damage or even collapse due to excessive displacements and/or very large lateral forces. For commonly used isolation bearings with a pure friction sliding surface, seismic forces may be reduced but displacements are often unconstrained. In this paper, an alternative seismic bearing system, called the cable-sliding friction bearing system, is developed by integrating seismic isolation devices with displacement restrainers consisting of cables attached to the upper and lower plates of the bearing. Restoring forces are provided to limit the displacements of the sliding component. Design parameters including the leng.h and stiffness of the cables, friction coefficient, streng.h of the shear bolt in a fixed-type bearing, and movements under earthquake excitations are discussed. laboratory testing of a prototype bearing subjected to vertical loads and quasi-static cyclic lateral loads, and corresponding numerical finite element simulation analysis, were carried out. It is shown that the numerical simulation shows good agreement with the experimental force-displacement hysteretic response, indicating the viability of the new bearing system. In addition, practical application of this bearing system to a multi-span bridge in China and its design advantages are discussed.

关键词： isolated bridge cable-sliding friction bearing isolation device seismic performance restrained displacement earthquake damage

Experimental study on the seismic response of braced reinforced concrete frame with irregular columns

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Earthquake eng.neering and eng.neering Vibration 2011年第4期10卷 487-494页

作者： Xiao Jianzhuang Li Jie Chen Jun Department of Building eng.neering Tongji University Shanghai 200092 China state key laboratory for disaster reduction in civil eng. Tongji University Shanghai 200092 China

A 15-storey K-braced reinforced concrete model frame with irregular columns, i.e., T-shaped, L-shaped, as well as ＋-shaped columns, was constructed and tested on the six-degree-of-freedom shaking table at the state key laboratory for disaster reduction in civil eng.neering in Tongji, China. Two types of earthquake records, El-Centro wave （south-north direction） and Shanghai artificial wave （SHAW） with various peak accelerations and principal-secondary sequences, were input and experimentally studied. Based on the shaking table tests and theoretical analysis, several observations can be made. The failure sequence of the model structure is brace→beam→column→joints, so that the design philosophy for several lines of defense has been achieved. Earthquake waves with different spectrums not only influence the magnitude and distribution of the earthquake force and the storey shear force, but also obviously affect the magnitude of the displacement response. The aftershock seismic response of previously damaged reinforced concrete braced frames with irregular columns possesses the equivalent elastic performance characteristic. Generally speaking, from the aspects of failure features and drift ratio, this type of reinforced concrete structure provides adequate earthquake resistance and can be promoted for use in China.

关键词： seismic response reinforced concrete braced frame irregular columns

Comparison study of two criteria for identification of structural dynamic stability

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Science China(Technological Sciences) 2019年第5期62卷 856-867页

作者： ZHOU Hao LI Jie School of civil eng.neering Tongji University state key laboratory of disaster reduction in civil eng.neering

Dynamic stability analyses of structures are becoming increasing prevalent in applications for tall buildings and space structure designs. This paper presents an effective energy criterion for identifying the dynamic stability of generalized structures through the modification of an earlier developed energy criterion for hardening structures. Two time-varying effective energy indices are introduced to account for the dynamic stability of both the hardening and deteriorating structures; one for the description of structural properties, i.e., the structural effective intrinsic energy, and the other for the measurement of the input energy, i.e., the valid external work. It is shown that a structure's stability can survive provided the effective intrinsic energy is always less than the valid external work during a dynamic excitation. The first passage of the effective intrinsic energy over the valid external work indicates the dynamic instability of the structure. A comparison study is carried out regarding the validity and applicability between the energy and effective energy criteria as applied to the dynamic stability analysis of three different structures.

关键词： identification criterion dynamic stability effective intrinsic energy valid external work deteriorating structure

Elastoplastic damage model for concrete based on consistent free energy potential

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Science China(Technological Sciences) 2014年第11期57卷 2278-2286页

作者： ZHANG Ji LI Jie state key laboratory for disaster reduction in civil eng.neering Tongji University

The aim of this study is to formulate an appropriate free energy potential for inelastic behavior of concrete and construct an elastoplastic damage model on a more rational basis. The concept of effective plastic energy storage rates is proposed, which are conjugate forces of hardening variables in an undamaged configuration. Then an analogy between the evolution of harden- ing variables and that of a plastic strain is used to postulate the formulation of plastic free energy. This formulation reflects the specific characteristics of a certain plasticity model, so it can serve well as a thermodynamic link between plasticity and dam- age. By combination of the general formulation of free energy with the double hardening plasticity theory and two-parameter damage expression, a thermodynamically well-founded elastoplastic damage model for concrete is constructed. The operator split algorithm is emploved, and the numerical simulations a^ree well with a series of material tests.

关键词： free energy plastic energy storage damage energy release constitutive model concrete

Experimental study of wind loads on cylindrical reticulated shells

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Applied Mathematics and Mechanics(eng.ish Edition) 2013年第3期34卷 281-296页

作者：黄鹏周晅毅顾明 state key laboratory of disaster reduction in civil eng.neering Tongji University

The cylindrical reticulated shell structures without side walls, which are normally arranged in pairs, are usually used as dry-coal sheds in a thermal power plant. The wind loads of these shells do not exist in standards or codes. Therefore, this study investigates the mean and fluctuating wind loads on a cylindrical reticulated shell with a rise-to-span ratio of 0.39 through a series of wind tunnel tests. The characteristics of the wind pressures on the upper and lower surfaces and the net pressures are presented. The results show that the wind direction and another shell structure significantly affect the wind loads on the principal shell. The most unfavorable wind direction is around 30~, whereas the effects of the wind field and the height of the coal stack are small. The surfaces of the shells are divided into nine blocks, and the block mean and fluctuating （rms） pressure coefficients suitable for eng.neering applications are given as references for wind load codes.

关键词： cylindrical reticulated shell dry-coal shed wind tunnel test block pressurecoefficient fluctuating pressure interference effect

Experimental investigation of damage behavior of RC frame members including non-seismically designed columns

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Earthquake eng.neering and eng.neering Vibration 2009年第2期8卷 301-311页

作者： Chen Linzhi,Lu Xilin,Jiang Huanjun and Zheng.Jianbo state key laboratory of disaster reduction in civil eng.neering,Tongji University,Shanghai 200092,China PhD Candidate Professor Associate Professor Master of eng.neering state key laboratory of disaster reduction in civil eng.neering Tongji University Shanghai China

Reinforced concrete （RC） frame structures are one of the mostly common used structural systems, and their seismic performance is largely determined by the performance of columns and beams. This paper describes horizontal cyclic loading tests often column and three beam specimens, some of which were designed according to the current seismic design code and others were designed according to the early non-seismic Chinese design code, aiming at reporting the behavior of the damaged or collapsed RC frame strctures observed during the Wenchuan earthquake. The effects of axial load ratio, shear span ratio, and transverse and longitudinal reinforcement ratio on hysteresis behavior, ductility and damage progress were incorporated in the experimental study. Test results indicate that the non-seismically designed columns show premature shear failure, and yield larger maximum residual crack widths and more concrete spalling than the seismically designed columns. In addition, longitudinal steel reinforcement rebars were severely buckled. The axial load ratio and shear span ratio proved to be the most important factors affecting the ductility, crack opening width and closing ability, while the longitudinal reinforcement ratio had only a minor effect on column ductility, but exhibited more influence on beam ductility. Finally, the transverse reinforcement ratio did not influence the maximum residual crack width and closing ability of the seismically designed columns.

关键词： reinforced concrete frame member cyclic test hysteresis behavior damage behavior seismic performance