The Structural Design of Tall and Special Buildings

doi: 10.1002/tal.1092pmid: N/A

Munir, A.; Warnitchai, P.

doi: 10.1002/tal.704pmid: N/A

SUMMARYRecently, the issue of large inelastic seismic force demands at severe ground shakings such as maximum considered earthquake level has been highlighted in the conventionally designed high‐rise reinforced concrete core wall buildings. Uncoupled modal response history analysis was used in this study to identify the modes responsible for the large inelastic seismic force demands. The identification of dominant modes and mean elastic design spectra of seven representative ground motions for different damping ratios has led to the identification of three control measures: plastic hinges (PHs), buckling‐restrained braces (BRBs) and fluid viscous dampers (FVDs). The identified control measures were designed to suppress the dominant modes responsible for the large inelastic seismic force demands. A case‐study building was examined in detail. Comparison of the modal as well as the total responses of the case‐study building with and without the control measures shows that all the control measures were effective and able to reduce the inelastic seismic demands. A reduction of 33%, 22% and 27% in the inelastic shear demand at the base and a reduction of 60%, 22% and 26% in the inelastic moment demand at mid‐height were achieved using the PHs, BRBs and FVDs, respectively. Furthermore, a reduction of about 30–40% in the inelastic seismic deformation demands was achieved for the case of the BRBs and FVDs. The study enables us to gain insight to the complex inelastic behavior of high‐rise wall buildings with and without the control measures. Copyright © 2011 John Wiley & Sons, Ltd.

Wong, Kevin K. F.; Harris, John L.

doi: 10.1002/tal.705pmid: N/A

SUMMARYSeismic fragility represents the probability that structural response exceeds a given performance limit state due to a specified intensity of ground motion, and it has a direct relationship with the cost of rehabilitating the structural system. In this research, a cost analysis framework based on seismic fragility to quantify the expected loss of the structural system was proposed. Incremental dynamic analysis was used to generate the fragility curves, and plastic strain derived from plastic energy dissipation was used to quantify the structural damage at a local level. Two moment‐resisting steel frames and 100 nonstationary Gaussian earthquake ground motions were simulated, and correlations between local damage states and global performance limit states were performed to facilitate the cost analysis study. The results showed that good correlations exist in seismic fragilities, and therefore, the repair cost of the structural system becomes quantifiable. Active control based on the optimal linear control algorithm was included as an auxiliary study to identify the sensitivity of the correlations. It is observed that significant cost reduction can be achieved for structures with few stories when active control is used but may not be cost‐effective if it is installed in taller structures. Published 2011. This article is a US Government work and is in the public domain in the USA.

Allahyari, H.; Keramati, A.; Taheri Behbahani, A. A.

doi: 10.1002/tal.709pmid: N/A

SUMMARY In this study, the seismic performance of special and intermediate moment‐resisting reinforced concrete frames are evaluated through nonlinear static and dynamic analysis. According to experimental studies, one of the most important parameters affecting the behavior of special and intermediate ductile reinforced concrete frames is the transverse reinforcement ratio. In this paper, constitutive law of material for concrete under the influence of various transverse reinforcement ratios have been derived using Mander et al. model, and 20 ground‐motion accelerograms have been utilized for dynamic analysis. Additionally, the results of pushover and incremental dynamic analysis were compared in order to evaluate seismic performance of the selected high‐rise structures. Results reveal that both types of reinforced concrete frames with beam‐hinge type failure mechanisms have ductile behavior. Special moment frames have higher ductility because of early entry into nonlinear range resulting in higher plastic rotations, which result in greater lateral displacements. Due to the differences in behavior of intermediate and special ductility frames, confinement has an important role in the ductile behavior of structures. Copyright © 2011 John Wiley & Sons, Ltd.

Lu, Xilin; Su, Ningfen; Zhou, Ying

doi: 10.1002/tal.717pmid: N/A

SUMMARY Standing 260 m above the ground, the super‐tall building employs steel reinforced concrete frame and reinforced concrete core wall system strengthened by a belt truss story to resist lateral and vertical loads. It has two setbacks in elevation. One is structurally designed by direct termination of vertical members, and the other is realized by inclining columns. Because of these characteristics, the building is classified as an irregular and complex structure. To investigate the seismic behavior of the structure under rare earthquake action, a refined finite element model was developed by using ABAQUS (Dassault Systèmes Simulia Corp., Providence, RI, USA). Nonlinear time history analyses were conducted using explicit integration method. The results show that the structural system has sufficient seismic capacity and ductility to resist rare earthquake. The plastic deformation capacity of this building can meet the requirement of Chinese code, and seismic performance objective of no collapse under rare earthquake can be reached. However, deformations were found concentrated in members within and adjacent to setback stories, at the bottom strengthening portion of core walls and its upper story where lateral stiffness suddenly changed. It was suggested that transfer stories should be placed above or below these stories to improve the concentration of strain and deformation. Copyright © 2011 John Wiley & Sons, Ltd.