Effect of Cast-in-Place Beams on Seismic Performance of Precast Shear Walls

There is a drastic change in design and construction trends of underground structures, where a precast concrete (PC) shear wall system is quickly replacing a cast-in-place (CIP) diaphragm wall (that is, the so-called slurry wall) system in urban areas for better constructability and reliable performances. However, it is chal-lenging to achieve the proper coupling action or composite perfor-mance through vertical connections between adjacent PC walls and that in horizontal connection between PC walls and founda-tions to satisfy the seismic design criteria specified in codes. To this end, this study introduces cast-in-place (CIP) cap beam and waling beam at the top and midheight of PC walls to connect individual precast wall panels by means of a coupling action. Precast speci-mens were carefully designed to be code-compliant as intermediate precast shear wall systems, and were then fabricated and tested under the reversed cyclic loads to evaluate seismic performances. Detailed numerical models were also developed to identify how CIP beams can effectively improve the seismic performance of a precast shear wall system by restraining the free rotation and axial deformation of individual precast wall panels.