Crashworthiness Of Existing RC Parapets With Sustainable Rehabilitation

Ultra high performance cementitious composites( UHPCC) has excellent performances including mechanics and durability, and has important application prospects in civil engineering infrastructure rehabilitation. Recently, some research work were carried out about the comprehensive rehabilitation including durability and mechanical performances in existing reinforced concrete structures based on UHPCC internationally. Overall, the comprehensive rehabilitation of existing reinforced concrete structures based on UHPCC has been one of the important research directions of UHPCC engineering application. At present, the protection layer on Existing reinforced concrete Bridge Parapets(EBP) drops because of aggressive environments and de-icing salts, which is widespread. The effectiveness of the rehabilitation measures used in the current project is not significant. And the frequent rehabilitation of EBP has to be done.The application of UHPCC in rehabilitation of EBP has many advantages. On the one hand it can improve EBP’s durability; on the other hand, the mechanical performances of EBP are increased, such as crashworthiness. Therefore, EBP rehabilitation based on UHPCC is an advanced rehabilitation technique which belongs to multi-functional rehabilitation including durability and mechanical performances. UHPCC rehabilitation layer’s design parameters, structural degradation parameters(such as corrosion rate of steel bar), load parameters(such as collision load information) and the combined effects of these parameters influence the comprehensive rehabilitation of structural performance, which is the basic problem in this kind of comprehensive rehabilitation design. But there are few work carried out in this area.The crashworthiness of the typical reinforced concrete parapets rehabilitated with UHPCC was analyzed in this paper based on the nonlinear finite element method. The finite element model was verified by the experimental verification of the similar structure, which is reinforced concrete cantilever slab based on UHPCC rehabilitation in the early research. In this paper, the influence parameters of the vehicle-parapets collision model were divided into two parts, namely the material internal factors, including the rebar corrosion ratio, UHPCC rehabilitation layer thickness and the fiber volume fraction; load external factors including impact speed, impact angle and vehicle mass. The effect of the internal factors and the external factors were analyzed on this basis of the model. The influence of these parameters on crashworthiness of EBP including the maximum dynamic deformation, the peak impact loads were revealed. And a new sustainable rehabilitation method of existing RC parapets was proposed based on the level of crashworthiness.