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doi: 10.1002/tal.1098pmid: N/A
Damped outriggers for tall buildings draw increasingly attentions to engineers. With a shaking table test, two models of a high‐rise steel column‐tube structure are established, one with outriggers fixed to the core and hinged at the columns, whereas the other's cantilevering outriggers are connected to columns by viscous dampers. According to their dynamic properties, five earthquake waves are selected from the Ground Motion Database of Pacific Earthquake Engineering Research Center (PEER), and two artificial waves are generated by software SIMQKE_GR. Under various peak ground accelerations (PGAs), nonlinear time‐history analysis is applied to compare structural elastic seismic responses, including accelerations, inter‐story drifts, base shear force, damper's response and additional damping ratios. It is concluded that under minor earthquakes, accelerations, inter‐story drifts and base shear force of structure with damped outriggers are larger than or nearly equal to those of the one with fixed outriggers, and the viscous dampers hardly work. But as PGA increases, the contrary situation happens, and the effect of viscous dampers is enhanced as well. The additional damping ratio reaches around 4% under mega earthquakes. Copyright © 2013 John Wiley & Sons, Ltd.
D'Amore, Enzo; Amaddeo, Carmen; Astaneh‐Asl, Abolhassan
doi: 10.1002/tal.1100pmid: N/A
This paper is a study of a six‐story welded steel moment‐resisting frame instrumented by California Strong Motion Instrumentation Program. Several earthquakes had shaken the building, and its response of strong motion data recorded during the earthquakes were made available. In particular, the Whittier Narrows (October 1987), Sierra Madre (June 1991), Northridge (January 1994) and Chino Hills (July 2008) earthquakes were considered in the studies reported here.
doi: 10.1002/tal.1101pmid: N/A
Using rocking wall systems is a recent technique to improve seismic behavior in reinforced concrete structures. This paper compares three 10‐story and three 20‐story reinforced concrete frames (moment‐resisting frames) with intermediate ductility, reinforced concrete frames with shear wall, and reinforced concrete frames with controlled rocking wall (RCRW) by the use of pushover analysis. At the end of the research, the wall in a 20‐story RCRW system is post‐tensioned then analyzed, and its results were compared with RCRW results. Simulation and numerical analysis were performed with OpenSees software. The results show that plastic hinge formation and inter‐story drifts are well distributed in the structure with rocking wall system in comparison with the other systems. Meanwhile, energy dissipation and displacement ductility are increased in RCRW frames. With post‐tensioning wall in RCRW, the drift ratios are more uniformed. Copyright © 2013 John Wiley & Sons, Ltd.
Yiu, C.‐F.; Chan, C.‐M.; Huang, M.; Li, G.
doi: 10.1002/tal.1102pmid: N/A
This paper presents a practical method for evaluating lateral‐torsional coupling in the elastic earthquake response of asymmetric multistory buildings. A transformation technique is first developed to shift the floor centers of mass of an asymmetric building to new reference positions where the sum of the squares of all floor rotations of the building due to lateral inertia loads is a minimum. By setting the locus of the floor centers of mass of the building at the new reference positions, a representative eccentricity and an effectively uncoupled system for the building can be established on the basis which an equivalent eccentric single mass system can be developed. The additional lateral translations caused by seismic torsional effects in the building can be analytically determined and expressed in terms of the representative building eccentricity and the uncoupled periods evaluated using the effectively uncoupled system. The effectiveness and practicality of the proposed method are illustrated with two 30‐story practical buildings. Copyright © 2013 John Wiley & Sons, Ltd.
Rahbari, Nima Mohajer; Talatahari, Siamak
doi: 10.1002/tal.1104pmid: N/A
Many severe dynamical loadings such as earthquakes and strong winds may subject to structural systems during their lifetime and lead to changes in structural characteristics. Hence, employing an adaptive control strategy that can deal with these alterations compound with design of the structural elements would undoubtedly be the most effective alternative design for the old‐fashioned design methods, which are relatively inefficient in response to these unforeseen conditions. In the current study, benefits of employing the modern control systems for design of tall buildings in comparison with the uncontrolled traditionally designed structures are thoroughly investigated. To contract the vibrational responses due to seismic excitations, the innovative direct‐modulating semi‐active controller is designed for magneto‐rheological dampers, which are installed in an 11‐storey sample building converting it to a smart structure. Copyright © 2013 John Wiley & Sons, Ltd.
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