An evaluation of force-based design vs. direct displacement-based design of
jointed precast post-tensioned wall systems
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M. Ataur Rahman1 and Sri Sritharan2
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1. 414 Town Engineering building, Iowa State University, Ames, IA 50011,
USA
2. 406 Town Engineering building, Iowa State University, Ames, IA 50011, USA
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Abstract:The unique features of jointed
post-tensioned wall systems, which include minimum structural damage and
re-centering capability when subjected to earthquake lateral loads, are the
result of using unbonded post-tensioning to attach the walls to the foundation,
along with employing energy dissipating shear connectors between the walls.
Using acceptance criteria defined in terms of inter-story drift, residual drift,
and floor acceleration, this study presents a multiple-level performance-based
seismic evaluation of two five-story unbonded post-tensioned jointed precast
wall systems. The design and analysis of these two wall systems, established as
the direct displacement-based and force-based solutions for a prototype building
used in the PREcast Seismic Structural Systems (PRESSS) program, were performed
at 60% scale so that the analysis model could be validated using the PRESSS test
data. Both buildings satisfied the performance criteria at four levels of
earthquake motions although the design base shear of the direct
displacement-based jointed wall system was 50% of that demanded by the
force-based design method. The study also investigated the feasibility of
controlling the maximum transient inter-story drift in a jointed wall system by
increasing the number of energy dissipating shear connectors between the walls
but without significantly affecting its re-centering capability.
Keywords:concrete; precast; unbonded
post-tensioning; wall; building code; performance-based evaluation; force-based
design; direct-displacement based design
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