Optimum design of post-tensioned concrete flat slabs using finite element method

Post-tensioned slabs commonly used in building and bridge construction are grouped into two basic categories. These are the unbonded and bonded systems. This thesis investigates the structural behaviour of post-tensioned one-way concrete slabs. A nonlinear finite element model for the analysis of post- tensioned unbonded and bonded concrete slabs at elevated temperatures was developed. The numerical analysis was conducted by the finite element ANSYS software and was carried out on different one-way concrete slabs chosen from literature. A parametric study was conducted to investigate the effect of several selected parameters on the overall behavior of post-tensioned one-way concrete slab. These parameters include the effect of tendon bonding, thermal loading and tendon profile. The results showed that restrained post tensioned slab with bottom surface hotter has smaller failure load capacity. Optimization in its wide sense can be used to solve many engineering problems. A three-dimensional finite element model for the optimization of bonded and unbonded post-tensioned concrete one-way slab was also developed in this study. The total weight of post-tensioned tendons was considered as the objective function. It is concluded that the tendon area design variable of post- tensioned slab is very effective due to, it enables us to find the optimum design of post-tensioned tendon with low cost under suitable service conditions.