The Research Of Stress Analysis And Computational Method Of Separative Box-girder Bridge Designing

Prestressed concrete separative box-girder with its artistic contour, small cross-sectional, moreover can effectively use the high strength material, the total cross-section participate working, the better surmounts ability, so it is widely used in beam bridge in recent years. Along with the popularization and application of separative box-girder, people already not solely requested the structure analysis to be able to reflect the actual situation, hoped could obtain the satisfactory result quickly and economically. According to the materials, the author induced some insufficiency about the researching of separative box-girder bridge, then carry on studies and draws the conclusion below:1. The method of calculating transverse distribution of loads of separative box-girder bridge exist difference and the irregular plasticity in the designing. The author uses two kind of methods analysis the simply supported separative box-girder bridge and the continuous separative box-girder bridge, the result of the two method approaches equally, the result of the method of rigidity(hinge) girder can satisfy the design precision, moreover comparing with the complex finite element method, the method of rigidity(hinge) girder has the advantages of succinct and fast.2. For simply supported separative box-girder, the traverse coefficient of middle girder changes sharply in the bridge span, we can use the cross center traverse coefficient to calculate the bending moment of various sections, at the same times, we should as far as possible to check the endogenic force of some special sections. The traverse coefficient of the side girder changes gentle in the bridge span, we may use the value of cross center to replace the value of other sections. The error is not big. When calculating the load traverse coefficient around the support, the principle of release lever is no longer suitable in this situation.3. The method of equivalent stiffness calculating the traverse coefficient of continuous beam indirectly is as suitable as the spatial finite element method, the results of two method tallies well. We can calculate the traverse coefficient of continuous beam more conveniently when we combine the method of equivalent stiffness and the method of rigidity(hinge) girder.4. The space finite element analysis indicated that the prestressed concrete box girder's stress and the distortion are sensitive to the change of gradient of temperature pattern. Therefore, we should as possible as we can choose suitable gradient of temperature for box girder according to the environment and the geographical position and other practical details of the highway bridge, in the foundation of researching actual material make reasonable determination. At the same time, we must consider the construction feather of the box girder and carry on the essential revision about the gradient of temperature.5. In the measure of controlling temperature stress and preventing box girdercracks, we should carries on the combination checking to the pivot and the cross center section in order to control the stress not oversized. Besides, arranging certain quantity of structural reinforcement at the control spot can make the crack to be even and prevent the developing of crack.