Effect of ground motion directionality on the seismic response of base isolated buildings pounding against adjacent structures

2020 ◽  
Vol 207 ◽  
pp. 110202 ◽  
Author(s):  
Eftychia A. Mavronicola ◽  
Panayiotis C. Polycarpou ◽  
Petros Komodromos

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
Piotr Adam Bońkowski ◽  
Juliusz Kuś ◽  
Zbigniew Zembaty

AbstractRecent research in engineering seismology demonstrated that in addition to three translational seismic excitations along x, y and z axes, one should also consider rotational components about these axes when calculating design seismic loads for structures. The objective of this paper is to present the results of a seismic response numerical analysis of a mine tower (also called in the literature a headframe or a pit frame). These structures are used in deep mining on the ground surface to hoist output (e.g. copper ore or coal). The mine towers belong to the tall, slender structures, for which rocking excitations may be important. In the numerical example, a typical steel headframe 64 m high is analysed under two records of simultaneous rocking and horizontal seismic action of an induced mine shock and a natural earthquake. As a result, a complicated interaction of rocking seismic effects with horizontal excitations is observed. The contribution of the rocking component may sometimes reduce the overall seismic response, but in most cases, it substantially increases the seismic response of the analysed headframe. It is concluded that in the analysed case of the 64 m mining tower, the seismic response, including the rocking ground motion effects, may increase up to 31% (for natural earthquake ground motion) or even up to 135% (for mining-induced, rockburst seismic effects). This means that not only in the case of the design of very tall buildings or industrial chimneys but also for specific yet very common structures like mine towers, including the rotational seismic effects may play an important role.





2011 ◽  
Vol 16 (3) ◽  
pp. 364-374 ◽  
Author(s):  
Aman M. Mwafy ◽  
Oh-Sung Kwon ◽  
Amr Elnashai ◽  
Youssef M. A. Hashash


1992 ◽  
Vol 19 (1) ◽  
pp. 117-128 ◽  
Author(s):  
A. Ghobarah ◽  
T. Baumber

During recent earthquakes, the documented cases of collapsed unreinforced brick masonry industrial chimneys are numerous. Observed modes of structural failure are either total collapse or sometimes collapse or damage of the top third of the structure. The objective of this study is to analyze and explain the modes of observed failure of masonry chimneys during earthquake events, and to evaluate two retrofit systems for existing chimneys in areas of high seismicity. The behaviour of the masonry chimney, when subjected to earthquake ground motion, was modelled using a lumped mass system. Several actual strong motion records were used as input to the model. The shear, moment, and displacement responses to the earthquake ground motion were evaluated for various chimney configurations. It was found that the failure of the chimney at its base is the result of the fundamental mode of vibration. Failure at the top third of the structure due to the higher modes of vibration is possible when the chimney is subjected to high frequency content earthquakes. Higher modes, which are normally not of concern under wind loading, were shown to be critical in seismic design. Post-tensioning and the reinforcing steel cage were found to be effective retrofit systems. Key words: masonry, chimneys, behaviour, analysis, design, retrofit, dynamic, earthquakes, seismic response.





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