Experimental and Numerical Evaluation of New Seismic Details for Connection of Post-tensioned Flat Slabs to Edge Steel Columns

One type of structural systems that has received growing attention worldwide consists of flat slabs supported by steel columns. A key issue in these systems is the connection between slab and column. Although details for the connections of non-prestressed slabs are published frequently, but little details are reported for post-tensioned ones. In an experimental program, new details are proposed and examined for the connection of post-tensioned flat slab to edge steel column. The details include steel plates at the bottom and top of the slab, vertical stiffeners and vertical shear bolts. The connection is examined under cyclic lateral load test. The connection shows satisfactory seismic behavior, exhibits stable nonlinear response up to 3.5%drift ratio, and sustains gravity load capacity under relatively large lateral drift. To evaluate the effect of different details, a finite element model is developed and calibrated by the test results. According to the model, the effect of longitudinal and transverse arrangement of post-tensioning tendons and the level of prestressing of slabs are investigated. The study shows that the arrangement of banded tendons in the longitudinal direction and distributed in the transverse direction exhibits higher load capacity (about 20%) relative to the reverse arrangement (distributed in the longitudinal direction and banded in the transverse direction). The test also shows that increasing the average prestressing level from 1 MPa to 1.75 MPa results in an increase of about 30% of the load capacity of the connection. In this article, details of the studies and the obtained results are reported.

Keywords: Post-tensioned flat slab; Steel column; Connection details; Cyclic load test; Prestressing level; Tendons arrangement