Experimental Study On The Relationship Between Surface Morphological And Damage Of Reinforced Concrete Hollow Slab Bridge

Based on the research of bridge structural behavior evolution theory and safety monitoring method,which funded by National Key Basic Research Special Foundation of China(2012CB723305),a whole process experiment of load-damage-deformation is carried out on the reinforced concrete hollow slab bridge.The main work and conclusions are as follows:1.A 13 m span concrete hollow slab bridge was used as the prototype,a test model was designed with the scale of 1/2.5,and the 5.2m span model bridge was built in structure laboratory.All of loading plans and test plans were work out according to the experimental purpose.2.A cyclic loading test was carried out under the normal using condition of model bridge,and the results show that: Load and deflection are showed a linear relationship about all hollow slabs,crack width of slab bottom are less than 0.2mm.While loading on the side slab,the vertical deformation of load bearing slab is maximum,the vertical deformation of other slabs show a decreasing trend and even to an upturned deformation;with load increasing,longitudinal dislocation is gradually appeared between side slab and secondary side slab.While loading on the middle slab,load bearing slab has a little vertical deformation,the deformations of all hollow slabs tend to be consistent,and there have no obviously longitudinal dislocation between middle slab and adjacent slabs.3.The destructive loading tests were carried out on the side plates and middle plate respectively,and the results show that: Load and deflection are showed a nonlinear relationship about all hollow slabs while closed to failure load,there is a rapid growth of vertical deformation on the load bearing slab,the vertical deformation of other slabs show an upturned deformation trend,longitudinal dislocation is appeared between load bearing slab and adjacent slabs.There appeared two longitudinal parallel cracks at the bottom of slab after the load bearing slab destroyed,accompanied by mesh cracks and concrete spalling.4.The loading tests were carried out after the hinge joints failure,and the results show that: The deformation of hollow slab bridge had a good coordination before hinge joints damaged.After hinge joints damaged,there is a large vertical deformation on the load bearing slab,and longitudinal dislocation is appeared between load bearing slab and adjacent slabs.The hinged joints damage greatly reduce the bearing capacity of hollow slab bridge.Eventually,the bearing capacity of side plate and secondary side plate are decreased by 46.4% and 55% respectively.5.The digital surface morphological models of hollow slab bridge were built by experimental data.Combined with the method of "Structural damage identification of location and degree based on bridge deflection curvature",the characteristic deflection curve and curvature were analyzed while hollow slab bridge was loading,the influence of different damage degree and load grade were studied on deflection curvature.The results show that: The deflection curvature mutation has a correspond relationship with structural damage location.There is positive correlation between the degree of curvature mutation and the degree of structural damage,the hinged joints are easier to identify the damage than cracks,and side slabs are more likely to identify the damage directly through the deflection curve.