EVALUATION METHOD FOR JOINT LOAD TRANSFER EFFICIENCY IN CONCRETE PAVEMENTS

Abstract

In concrete pavement, to reduce the stress which occurs in concrete slabs by allowing movement of the con­ crete slabs such as expansion, shrinkage and warping, various types of joints are installed. These joints become structural weak points. In most cases, the failure of con­crete pavement advances from joints. The joints must act as the structure by which the load is transmitted between loaded slabs and unloaded slabs. Therefore, primarily dowels have been used. There is a large influence by load transfer on the service performance of concrete pavement. However in the joints of RCCP, sawn joints have generally been used. The capability of load transfer in these sawn joints is dependent on the width of the crack opening. With concrete pavement containing RCCP, it is important to establish a technique to evaluate reasonably the capability of load transfer. So far, the capability of load transfer has been evaluated by the difference of deflection in both loaded slabs and unloaded slabs. How­ ever, it can be said that the load transfer efficiency does not represent directly the mechanical behavior of joints. Therefore, when the behavior of joints is mechanically evaluated, it is necessary to introduce a mechanical model that properly simulates joint behavior. This study was conducted to develop a mechanical model properly simulating joints. The following investigations were conducted : 1. Construction of a test road for RCCP 2. Measurement of deflection by FWD at joints 3. Calculation of load transfer efficiency using deflec­tion 4. Proposal of shear spring model 5. Determination of the coefficient of shear spring by backcalculation from FWD deflections 6. Stress calculation near joint edges using shear spring model