Structural design of high‐rise buildings using steel‐framed modules: A case study in Hong Kong

Steel‐framed modular buildings afford certain advantages, such as rapid and high‐quality construction. However, although steel‐framed modules have been adopted in several countries, most of them are limited to low‐to‐medium‐rise structures; modular high‐rise buildings are rare. This study proposes a feasible structural design solution for high‐rise buildings using a steel‐framed modular system. A 31‐story student hostel building in Hong Kong is redesigned as a steel‐framed modular building and used as a case study. The finite element models of the building are formulated, and the structural behaviors under wind and earthquake load scenarios are compared. Moreover, the structural design process used for the 31‐story building is applied to design a hypothetical 40‐story modular building to further examine the proposed design solution. The numerical analysis results indicate that the roof lateral displacements and interstory drift ratios of the redesigned modular building are within the allowable limits of design codes; moreover, the modular connections behave elastically under the most adverse loading scenarios. Accordingly, the proposed solution can be used to design steel‐framed modular buildings of up to 40 stories, while complying with relevant wind and seismic codes.     

Seismic performance of high‐rise building with a rock‐slip isolation system with cables

To avoid the overturning hazard of high‐rise buildings with traditional isolation technology, a rock‐slip structure with cables (RSSC) was proposed to improve their seismic performance. The mechanical model was established, and the motion behaviour equation of the RSSC was derived. Shake‐table tests of the RSSC were performed, and the results were compared with the corresponding finite‐element model simulations. The influences of key structural parameters and earthquake motion characteristics were analysed. The study results showed that the RSSC could effectively reduce the internal seismic force response and interlayer deformation under a severe earthquake, as well as decrease the overturning probability. The seismic reduction effect was influenced by the prestressed force, the aspect ratio of the structure, and the friction coefficient between the superstructure and foundation as well as seismic site type. The motion equation derived in this paper can be used to theoretically predict the motion behaviour of RSSC.     

Wind‐induced torsion vibration of the super high‐rise building of Shenzhen Energy Center

The synchronous multipoint scanning system technique in wind tunnel tests and random vibration theory method were used to analyze the wind‐induced torsion vibration of some irregularly shaped super high‐rise buildings in downtowns. The torsion vibration modes and the spectra of torsion wind load were studied, and the proportions of mean wind torsion, inertia torsion and the mass eccentricity torsion caused by horizontal inertia forces are discussed. The following conclusions can be drawn. First, the third and fourth modes have torsion vibration shapes, and their frequencies are in the high‐energy area of the spectra of the torsion wind load; the third and fourth modes are included in the resonant component of the spectra of the top torsion angle of the building, and the third mode is dominant. Second, the torsion stiffness is weak in the high stories of the building, so the inertia torsion is dominant, whereas the torsion stiffness is strong in the low stories; the mean wind torsion is dominant. The proportion of the mass eccentricity torsion moment caused by horizontal inertia forces is small. Finally, the wind‐induced torsion moment at a 90° wind angle is the largest, whereas the torsion eccentricity is 46% of the radius of gyration and is much greater than the mass eccentricity; thus, the wind‐induced torsion should be considered. The wind‐induced torsion vibration of the building is sensitive to wind directions. Copyright © 2011 John Wiley & Sons, Ltd.     

Numerical study of the static and dynamic characteristics of reinforced concrete cassette structures for high‐rise buildings

High‐rise buildings are extensively built in China, and the structure of these buildings is composed of different types of conventional system of which framed structures are more commonly employed. A new cassette structure with advantageous performance properties is proposed. Static and dynamic numerical simulations were applied to investigate the characteristics of this new structure. First, the components and other details are presented. A comparative analysis was conducted between the cassette structure and traditional structures using eight finite models with fiber elements in three different heights. A static pushover analysis and an incremental dynamic analysis were conducted based on 18 near‐ground motion records recommended by the Federal Emergency Management Agency. The seismic characteristics, deformation curve, interstory drift, roof displacement, and fragility curve are investigated. Based on the analysis of the models with three different heights and the variety of seismic records, the economic advantage and application of cassette structures for building industrialization are also discussed.     

An estimate on in‐construction differential settlement of super high‐rise frame core–tube buildings

To physically identify the mechanisms behind the development of in‐construction settlement of super high‐rise frame core–tube buildings, a simplified approach is developed by the full understanding about the typical structural layouts, specific construction feature, and load transfer path of those buildings as well as time‐dependent effects. With the reference to several typical structural layouts, a simplified one‐bay multistory model is developed that consists of two overall vertical components and horizontal components representing the exterior columns, core tubes, and beams (or mega trusses), respectively, in those super high‐rise buildings. Based on this model, a simplified approach with a so‐called “global–local” strategy is proposed to account for the difference in the settlement of the corner columns and side columns. The leading construction and final screwing at the rigid connections between beams (or trusses) and exterior columns, which are commonly implemented during the construction of those buildings, are seriously addressed in the simplified approach, as well as strengthened floors and time‐dependent effects. The applicability and accuracy of the proposed approach is demonstrated by a 128‐story 606‐m‐level super high‐rise frame core–tube building. The proposed simplified approach can be helpful for the development of preliminary construction schemes and the control strategy for differential settlement.     

Alternative approach to compute shear amplification in high‐rise reinforced concrete core wall buildings using uncoupled modal response history analysis procedure

The seismic response of the high‐rise reinforced concrete (RC) wall structures is really complicated as several vibration modes other than the fundamental mode normally contribute significantly to the response—commonly recognized as ‘higher mode effects’. Response spectrum analysis (RSA) procedure, which can account for higher mode effects, is usually employed to compute the seismic design demand for the high‐rise structures. Recent studies show that the inelastic seismic force demands obtained from the rigorous nonlinear response history analysis procedure are much larger than the seismic force design demands obtained from the code‐based RSA procedure for the high‐rise RC wall structures. Though, the nonlinear response history analysis procedure is widely accepted for its ability to provide the most accurate estimate of nonlinear seismic responses, the obtained responses are generally so complex that it is quite difficult for engineers to grasp the overall picture of the responses and gain some insight into them and use them to understand the cause of high seismic demands. Another important issue related to the nonlinear seismic response prediction of the high‐rise RC wall structures is the realistic and accurate numerical modeling of RC walls. In this study, a simplified but reasonably accurate procedure called the uncoupled modal response history analysis procedure is used to interpret the complex nonlinear behavior of high‐rise RC wall structures. Moreover, a finite element model based on modified compression field theory is employed for accurate numerical modeling of RC walls by incorporating the axial‐flexure‐shear interaction. This study, by making use of a better computer modeling approach and an in‐depth analysis by modal decomposition, aims to resolve some of the unanswered questions regarding realistic prediction of nonlinear seismic demands of high‐rise structures.     

Shaking table test and numerical simulation on vibration control effects of TMD with different mass ratios on a super high‐rise structure

In this paper, the influence of mass ratio on the vibration control effects of tuned mass damper (TMD) on a super high‐rise building has been investigated. A 1/45 scaled model of a super high‐rise building was constructed, and the TMD with the mass ratio of 0.01, 0.02, and 0.03, respectively, was suspended on the top. Shaking table test and the corresponding numerical simulation were carried out to make a further understanding of the damping mechanism. The structural performance with or without TMD was comparatively studied. The results show that larger mass ratio can improve the control effects under frequent earthquake, but the control effects increase little with the increase of mass ratio under rare earthquake due to structural damages, accompanied by stiffness degradation and nonlinear behavior of the main structure. In addition, some suggestions on the mass ratio selection are also proposed to generalize its applications.