INVESTIGATION OF STRUCTURAL BEHAVIOR OF POST- TENSIONED SLAB-COLUMN CONNECTION SUBJECTED TO PUNCHING SHEAR

Post-tensoned concrete flat slabs recently are widely used for multi-story structures of commercial, administrative,residential buildings of all types, offices, hospitals and parkings, specific in places that need to large spans. The major benefits of these slabs are the flush soffit, which provides the minimum story height, the maximum flexibility for horizontal service distribution, large spans,reduce cracks, more strength against water influence and lightweight slabs. Special construction technology lift-slabs method, which utilizes prefabricated post-tensioned slabs, makes the construction period significantly shorter, thus, making prestressed lift slabs a very cost effective solution. Most defect of this system is that increase shear force due to increase of span and post-tensioned slab is against punching shear failure due to transfer of shear and unbalanced moment. In most of cases,when slabs were post-tensioned, Some of the problems that our infrastructures with un-bonded post-tensioning facing today are: excess loading, inadequate maintenance, and need for periodic repair and strengthening. Some form of external reinforcement is needed to repair and strengthen these deficient structures. Fiber Reinforced Polymer (especially CFRP) system can be a possible strengthening system for the un-bonded post-tensioned concrete structures.In this thesis, strengthening post-tensioned slab-column connections with Fiber Reinforced Polymer studied with ANSYS, finite element softeware. First,it modeled an actual experimental post-tensioned slab for assurance of accuracy of numeral solution results and compare numeral model with experimental results. Then, three deferent models studied for concrete material. After calibere, widely studies is done about punching failure mechanism, main operative that create failure,cracking patterns and stress-strain states in ultimate state. Then, importance and influence of deferent parameters was studied about post-tensiond slab behavior, for example influence of post-tensioning value on slab behavior that experiment on them need much time and cost.