Study On Mechanical Behavior Of Skewed Hollow Slab Girder Bridge After Widening

Mechanical behavior of the widening structure of skewed hollow slab beam bridge is studiedin this paper based on the Fengshan separation interchange which locates in thexiamen-zhangzhou section of ShenHai highway line (fujian)(G15), this study will provide animportant reference for widening engineeting of skewed bridges. The main work are listed asfollows:1. The whole process of static test of a1:6.05scaled skewed model bridge with semi-rigidconnection was introduced as the engineering background of Fengshan separation inter-changebridge. The testing results were compared and analyzed with those from nonlinear finite elementcanculation, and the study focuses on the failure mechanism and ultimate load-carrying capacity.2. The strain and displacement of Fengshan bridge before and after widening weremonitored to reveal the mechanical behaviors of the widened skew slab bridges. Based on thesite monitoring and finite element analysis, the study was concentrated on the influence of theshrinkage and creep of concrete on the mechanics behaviors of the widened skew slabs bridge.Conclusions obtained from all studies are listed in the following:1. The damage of the longitudinal joint near midspan is mainly caused by flexure and tensionin action of symetrical concentrated load in the middle of the mid-span, while which was causedmainly by shear displacement near the bearing. The deformation difference between the two sidesof longitudinal joint in middle section was less than which in the bearing section.2. In action of symetrical concentrated load in the middle of the mid-span, the direction ofcrack distributed in the centre position of the mid-span always parallel to bearing line, while thedirecton of crack distributed near the slab free edges perpendicular to free edges; in addition,cracks was easy to appear along the obtuse angle bisector near the inner bearings, so thereinforcement should be enhanced.3. For the widen project of skewed hollow slab bridge, the shrinkage and creep of new bridgewill significantly increasing the strain in the bottom of middle section of in midspan, and thestrain caused by creep is about6to10times of the strain caused shrinkage; Shrinkage and creepwill cause the displacements of skewed bridge in all three directions, and the transversedisplacement is biggest, as longitudinal displacement is smaller and the vertical displacement issmallest.4. It is very impotant to choose reasonable time to constructe the longitudinal jiont of skewed widen bridge. If constructe earlier, old bridge may resist the disformation of newbridge due toshrinkage and creep, especially the transverse displacement, while the stress of the longitudinaljoint was reduced as delaying the constructing time. Therefore, for the widening proiect of specialtype bridge such as skewed bridge, the choice of jiont time need considering constructiontechnology, the project term requirement as well as the stress of the bridge,etal.5.Using the shrinkage and creep formulas provided by Code for Design of HighwayReinforced Concrete and Prestressed Concrete Bridges and Culverts(JTG D62-2004), thecalculation results are close to the testing results as considering the impact of the reinforcement.Shrinkage and creep calculation program using Fortran programning is suitable to calculate theshrinkage of concrete creep, and it can avoid the error from curve fitting by metal creepagemethod to simulate the shrinkage and creep action in finite element software.