Study On Impact Resistance Of Fiber-reinforced Rubberized Concrete For Structural Protection

Recently,China’s rapid socio-economic development and the significant increase in domestic and international trade have directly led to substantial growth in the volume of highway and waterway freight transportation.However,this has also resulted in more accidents between infrastructure and vehicles or vessels,and incidents of concrete bridges being impacted by trucks during their service life have become increasingly common in recent years.When such accidents occur,they not only pose a threat to people’s lives and property but also damage bridges as essential infrastructure,further expanding economic losses.Therefore,it is necessary to study the impact resistance of concrete bridges subjected to vehicle or vessel collisions,as well as bridge protection strategies.Although some studies have been conducted in this direction,the current research mainly focuses on the instantaneous response of pier impact,with few efforts to explore how to mitigate the negative effects of impact from the perspective of concrete protective structures.Achieving a balance between economic feasibility and practicality in the current studies on bridge-vehicle collisions is difficult.To address these issues,this thesis proposes the use of eco-friendly fiber-reinforced rubberized concrete as the protective jacketing for bridge piers.Fiber-reinforced rubberized concrete(FRRC)is a type of concrete that utilizes waste rubber as a partial replacement for natural aggregates to achieve a more sustainable and cost-effective construction material.Recent studies have shown that rubber concrete possesses exceptional ductility and energy dissipation characteristics,making it well-suited for application in the field of structural impact.This thesis conducts experimental and analytical research,filling the gap in current domestic and foreign research on the mechanical properties of rubberized concrete(Ru C)and FRRC under dynamic tensile and compressive loads.The study aims to contribute to the understanding of the performance of Ru C in structural impact protection and explore potential avenues for its application in this field through numerical simulation analyses.To address the above issues and research gaps,the specific work and innovations carried out in this paper are as follows:1.This thesis systematically conducts split Hopkinson pressure bar(SHPB)tests for Ru C and FRRC to study their dynamic mechanical properties under high strain rates in compression and splitting tensile tests.The influence of rubber aggregate and steel fiber on the dynamic mechanical properties of FRRC is qualitatively studied.Additionally,this thesis uses DIC strain analysis technology and high-speed cameras to quantitatively analyze the damage and crack initiation mechanisms and corresponding stress wave characteristics of Plain Concrete(PC),Fiber-Reinforced Concrete(FRC),Ru C,and FRRC under impact loads.The results indicate that compared with PC,Ru C exhibits higher strain rate sensitivity,better energy dissipation capacity,and higher ductility.Moreover,FRRC combines the characteristics of rubber concrete and fiber-reinforced concrete,exhibiting even stronger ductility and energy consumption ability.2.To address the shortcomings in the current research on the DIF model of concrete materials,this thesis proposes uncertainty probabilistic models for concrete and steel rebars using Bayesian analysis.It is found that the proposed probabilistic models eliminate the bias of deterministic models and exhibit higher accuracy.This thesis carries out K&C model parameter calibration for Ru C and FRRC.The parameter and damage evolution relationship between the replacement ratio of rubber aggregate and the volume fraction of fiber in terms of the strength and damage evolution of Ru C and FRRC are established and verified.3.Based on the above material characteristics and model studies,this thesis proposes using FRRC as a protective structure for bridge piers to reduce the damage of concrete structures after impact.The investigation encompasses Finite Element Analyses(FEA)of the instantaneous response and damage mechanism of bridge piers with rubberized concrete jacketing subjected to different impact scenarios by adjusting vehicle velocities and masses.Key factors influencing the impact resistances of concrete bridge piers were studied,and strategies for optimizing the protective performance of rubberized concrete were proposed.The results indicate that the impact force and post-impact displacement responses of bridge piers equipped with FRRC jacketing are significantly lower than those of ordinary concrete bridge piers,which indicates the FFRC jacketing has an excellent protective function.