Slab is one of the largest structural member, consuming a greater quantity of concrete. Voided slab is a new concept used for avoiding all concrete from the middle portion of a floor slab that is not performing any structural function which helps in the reduction of structural dead weight of the slab. In this study, an investigation of the thermo-structural behavior of voided slabs are done by considering spherical and hemispherical voids in between the reinforcements of the slabs which are supported by columns at all four corners of the slab. The solid slab is chosen as the control slab. For the nonlinear analysis uniformly distributed load is being applied at the top face and for the thermo-structural analysis temperatures and uniformly distributed load are applied at the bottom and top face of the slabs. The behavior of these voided slabs after the incorporation of various fiber-reinforced polymer (FRP) sheets like carbon, glass, aramid, and basalt at the bottom portion of the slabs (maximum up to two layers) is mainly studied. The entire study is being done using ANSYS software. Based on the results obtained, the solid slab was found to be better than the voided slabs in the absence of FRP sheets. With suitable FRP sheet reinforcements, it was observed that spherically voided slabs can perform as well as solid slabs, followed by hemispherically voided slabs.