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The objectives of this paper presented here are: 1) to check the limitations of the story shear-torque
surface based on the assumption of the idealized force-displacement relationship with experimental
results of earthquake simulation tests for 3 asymmetric single-story structures and 2) to develop it to be
more realistic three state spaces based on the bi-linear force-displacement relationship.
SHEAR-TORQUE RELATIONSHIP
There are three reinforced concrete single-story-building structures are designed to cater for the research
objectives. All experiments are carried out on a single-axial shake table installed by MTS in HK
Polytechnic University. Design detailing, instrumentations and ground excitations used in experiments
have been described in reference [2].
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Specimen 1/3 & Instrumentation
Fig.l Specimen Configuration & Instrumentation
Specimen2 & Instrumentation
Verification of the shear-torque relationship
Based on the assumption of idealized force-displacement relationship of structural members, J.C. De Le
Llera and A.K. Chopra (1995) developed a useful and effective method for understanding of
fundamental issues on seismic torsional phenomena of asymmetric structures. The most important
component of this approach is the use of the idealized yield base shear-torque (BST) surface of the
studied system. As examples, abovementioned 3 model structures studied in earthquake simulation tests
are used to examine both of the validity and the shortage of the idealized yield BST surface here for
understanding of the real seismic behavior of asymmetric systems correctly.
According to the method of reference [3] developed, the BST surfaces of the 3 asymmetric model
structures are founded respectively based on the assumption of idealized force-displacement relationship
while only single-directional ground excitation is considered, shown in fig. 8 for convenience of
comparison. The displacement-based approach that T. Paulay (2000) established is used in the
determination of the srif&iess of structural members. From fig.2, obviously, it can be found that the BST
surface of specimen2 expanded uniformly on the basis of specimenl while for that of specimenj, it is
skewed and extended to the 1 st and 3 rd quadrant relatively. In fact, due to the strength of concrete used in
the fabrication of specimen2 is higher than that of in specimenl, the strength of structural members in
specimen2 is uniformly increased. Together with the wall wl being arranged at the outer edge of
specimen! comparing with specimenl, the entire shear-torque resistant capacity is correspondingly
increased in specimen2 than mat of specimenl. The result is the space covered by the BST surface of
specimen2 is larger than that of specimenl. Similarly, the higher strength of concrete and the
reinforcement ratio used in specimenj particularly in walls than that of in specimenl, intensified the