The Optimum design of prestressed forced concrete higway bridge beams

SUMMARY Masters Thesis THE OPTIMUM DESIGN OF PRESTRESSED FORCED CONCRETE HIGHWAY BRIDGE BEAMS İhsan GüZEL Fırat University Graduate School of Nataral and Applied Sciences Department of Civil Engineering 1992, Page: 124 The prestressed concrete units widely used in the state and province roads by the Genaral Directorate of Itighway, recentlq. In this study the application and the design of prastressed concrete beams vere examined. Pre- tension and post-tension methods in isostatic systems and sliding and ankrobelman methods in hyperstatie systems were used in the westigation. U and 1 type cross-sectiore were U3ed in the bridge, viaducts, under- passes and over passes constructed as isostatic system. The slabs are u cross-sections, in the viaducts and long bridges were designed as hyperstatie system. The prestressed beams of the Aras Highway Bridge Constructed as isostatic over the Aras River nn the Aralı k-Sederel? Highway are in I cross sections. The bridge has a withdof 1 2 m, the platform width of 9,5 m and also has a length of 276 m. There are five pre- stressed beams along the span with 24cm slab thickness.The pre-otressed beams were designed according to dynamic loads H3Q-S24 using post-tension method. In a single beam there are four(5- 12) 270 K type pretension rods and stretching of these rods has been done with VSL pretension system using the E type anchorages. Totalaj 6700 fcN tension force has been applied on the four rods. By taking in to account the maximum and minimum tension force losses the allowable tension and compressiv force li mits of the concrete have been checked for the phasse3 of transferi ng and usi ng, given i n the T3 3233 specification. At the and of compulations, it ha3 been deserved that the choosen cross-section was ouer-critic. In additior. under the full (dynamic and dead loads) and the emty (dead loads) loadings contitrons the stressed at the top at the bottom sides of the cross-section has been determined. According to these results, it has been studied whether the maximum economy was pained or not, in the cross-section and in tension force. For the optimum design of the prestressed elements, dimensions of the cross-section can be determined using the tables. Additionally, it has been showed that it could be found the optimum pretension force by taking into account the deflections the stress limits, by using a linear programing techniques. The spesific properties and advantages of the pre-tension method in thell-type cross-section were summarized and the amount of material for one meter square of bridge slab. Key Words: Prestressed concrete beams, the optimum design.