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Earthquakes and Structures
  Volume 11, Number 6, December 2016 , pages 1027-1041
DOI: https://doi.org/10.12989/eas.2016.11.6.1027
 


Evaluating contradictory relationship between floor rotation and torsional irregularity coefficient under varying orientations of ground motion
Chunwei Zhang, Zeshan Alam and Bijan Samali

 
Abstract
    Different incident angles of ground motions have been considered to evaluate the relationship between floor rotation and torsional irregularity coefficient. The issues specifically addressed are (1) variability in torsional irregularity coefficient and floor rotations with varying incident angles of ground motion (2) contradictory relationship between floor rotation and torsional irregularity coefficient. To explore the stated issues, an evaluation based on relative variation in seismic response quantities of linear asymmetric structure under the influence of horizontal bi-directional excitation with varying seismic orientations has been carried out using response history analysis. Several typical earthquake records are applied to the structure to demonstrate the relative variations of floor rotation and torsional irregularity coefficient for different seismic orientations. It is demonstrated that (1) Torsional irregularity coefficient (TIC) increases as the story number decreases when the ground motion is considered along reference axes of the structure. For incident angles other than structure´s reference axes, TIC either decreases as the story number decreases or there is no specific trend for TIC. Floor rotation increases in proportion to the story number when the ground motion is considered along reference axes of structure. For incident angles other than structure´s reference axes, floor rotation either decreases as the story number increases or there is no specific trend for floor rotation and (2) TIC and floor rotation seems to be approximately inversely proportional to each other when the ground motion is considered along reference axes of the structure. For incident angles other than structure
 
Key Words
    torsional irregularity coefficient; floor rotation; asymmetric structure; time history analysis
 
Address
Chunwei Zhang, Zeshan Alam and Bijan Samali: Centre for Infrastructure Engineering, Western Sydney University, Penrith NSW 2751, Australia

Chunwei Zhang: School of Civil Engineering, Qingdao University of Technology, Qingdao, China
 

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