Stress Analysis Of Variable Cross-section Of Steel-concrete Composite Continuous Beam Bridge

In recent years, steel-concrete composite structures are widely used in engineering,but some issues of composite structures are not analyzed deeply by people, such asshrinkage and creep. Due to the Shrinkage and creep, internal forces and stress redistribution happened in composite structures, affect the carrying capacity of the structure;For composite continuous beam bridge, it is easy to crack in the bearing area for withstanding greater negertive moment and stress.In this paper, background engineering isZambia40m+60m+40m steel-concrete composite continuous beam bridge, and tit is caculated by Midas/Civil finite element analysis program, the analysis mainly from these aspects: stress and internal forces redistribution because of creep and temperature effecting, concrete bridge deck crack width under negative moment, construction methods of reducing tensile stress for the negative section of the bridge deck moment.Details are as follows:1. Analysis of internal forces and stress redistribution Generated by Creep. The influence of loading age and relative humidity on the creep effecte is analyzed, concreteshrinkage effect on the creep effect. Internal force in composite beam bridge is affected by temperature, it comes to a conclusion that temperature stress is mainly generatedbythe temperature difference between concrete and steel. The composite beam stressvariation is Also analyzed when the panel thickness and elastic modulus ratio changes.2. The capacity and crack width of the bridge deck under negative moment wascalculated, and the results shows that they all meet the requirements. Comparative analysis of deck crack width under different load cases was carried out, draw a negative impact on the most unfavorable load crack width of the bridge deck moment. Three factors of influence for bridge deck crack width that relative humidity, the impact of reinforcement ratio and the height of the bridge deck were analyzed.3. For the problem that continuous composite bridge deck bear a greatertensile stress under negative moment region, the influence of two construction methods that One-time casting and partitioning section of the casting of bridge deck on the beams stress was analyzed, the results show that the partition section pouring concrete bridge decks can effectively reduce the tensile stress of negative moment area of concrete bridgedecks, improves crack resistance of the bridge deck.4. Application of displacement method in the bridge construction was studied, contrastive analysis of stress when using the displacement method and not using displacement method was carried out,the results show that the negative moment region can shift the fulcrum of the bridge deck concrete to form a certain pressure stress reserves. Increase the amount so that the deck lift pivot preload stress increases while improving the lower support beams at the edge of the pressure, but also uninstall the role ofcreep increases linearly. Comparative analysis of the simultaneous lifting of the fulcrum and pivot in the order lifting the two programs, the results indicate that the latternegative moment area preload effect is more obvious.