Damage Controlling Performance of a Full Scale Unbonded Post-Tensioned Precast Concrete Beam


Abstract eng:
Twenty-some years ago, it was considered that safety was a major and only concern in designing building structures in an engineering society. However, the 1994 Northridge earthquake and 1995 Kobe Earthquake revealed that the general public does not share the same vision with the engineering society. Urban earthquakes of last twenty years made the general public and the engineering society confident that structures need to perform in a higher standard, that is, damage of structures should be minimal so that structures should keep their functions after multiple earthquakes. Since then, new structural systems such as base isolation system and response controlling system with dampers have been attracting attentions. However, these systems are not necessarily universal and other variations of structural systems are also needed to meet different demand. A self-centering rocking system using unbonded post-tensioned precast concrete members is one of good alternatives for damage-controlling structures. By using high quality precast concrete, the rocking system is very durable in long term and damage-resistant in a short term. Unbonded post-tensioned precast concrete system is able to reduce cracking as well as residual deformation/displacement and maintain structural functions for its self-centering property. In this research, a static loading test was conducted on a full-scale unbonded post-tensioned precast concrete Hshaped beam-column assemblage. The objective was to quantitatively evaluate the damage at different loading stages. The 600mm x 1000mm beam with clear span length of 11 meters was post-tensioned with four unbonded strands to column at both ends. Two columns had pin-joints at their top and bottom to simulate the intermediate story of a building. Two point loads of 230kN each were applied to the beam to simulate vertical load due to dead and live load. The experimental results showed satisfactory seismic performance with minor damage and less residual drift and the specimen conformed to requirements for continuous use of members defined in the AIJ guidelines. In addition, the residual crack width, residual deformation drift and equivalent damping ratio were evaluated using the AIJ guidelines to study the validity of the criteria. It was concluded that a full-scale unbonded post-tensioned precast concrete beam possessed good seismic performance of quick recovery and functional maintenance.

Contributors:
Conference Title:
Conference Title:
16th World Conference on Earthquake Engineering
Conference Venue:
Santiago (CL)
Conference Dates:
2017-01-09 / 2017-01-13
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 Record created 2017-01-18, last modified 2017-01-18


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