The Surface of Reinforced Concrete deck slab bridge is exposed to change in surface temperature, which is affected by different parameters and can produce additional stress. Previous studies and code provisions did not clearly investigate the temperature distribution along the depth of deck with the considerations of various parameters and they did not specify the effect of additional thermal stresses for different temperature distribution and different geographical location. This thesis investigates, the effect of topping asphalt thickness and span to depth ratio variation on temperature distribution along the depth, and also it conducts the linear and nonlinear analysis to specify the additional thermal stress values. Abacus finite element software is used to develop 3D models to preform heat transfer analysis and coupled temperature displacement analysis. The validation of finite element analysis was done with experimental work of T-Girder Bridge Lee (2012). The finite element analysis result shows good agreement with the experimental result with 0.63 of AAD. The analytical result of parametric studies on temperature distribution along the depth of deck slab bridge shows that the variation of toping asphalt and span to depth ratio highly affect the temperature gradient. For construction of small asphalt thickness over the deck of the slab bridge increases the temperature deference at top of deck more than 70% of deck slab construction without topping asphalt. Similarly, as span to depth ratio decreases the temperature deference was increased by more than 45%. From the comparison of temperature gradients, the Ethiopia Road Authority 2013 temperature gradient shows good agreement with the maximum temperature gradient of this study. The investigation of linear and nonlinear temperature load analysis indicates additional thermal stress highly affect the values of end moments and shear forces, but it reduces the magnitude of span moments and it changes the direction of deflections. Both Ethiopia Road Authority 2013 and American Association of State Highway and Transportation Officials 2012 bridge design codes, estimate small thermal stresses and recommended low amount of reinforcement area compared to this study. Therefore, the additional thermal stress shall be included in the governing load combination to design support moment and shear force of deck slab bridge, rather than it considered for serviceability requirements.