橡胶混凝土材料耗能特性及其在梁式桥防撞减振中的应用

Rubberized concrete is a composite material, which is based on concrete material and mixed with crumb rubber.Crumb rubber can not only improve anti-cracking ability and ductility, which makes concrete a stronger dissipation capacity, but also provide a new way to deal with scrap tire scientifically.The subject studies the dissipation performance of rubberized concrete firstly,and then carries out its application in anticollision and vibration reduction of girder bridge by combining theoretical method and experimental method.According to the level of material,component and structure, the dissipation performance of rubberized concrete and the influence of dynamic load characteristics on dissipation performance are obtained by axial hysteretic test, and the dissipation computational method of rubberized concrete is proposed. The influence of some parameters, such as clad material,cladding setting ways,thickness ratio and stiffness ratio of cladding and the original members,etc.,on the natural vibration characteristics,dynamic response and impact properties is studied by the experiment of adding rubberized concrete cladding to the ordinary concrete members,and optimization design method for anticollision and vibration reduction of rubberized concrete is proposed.The collision response and seismic response of girder bridge with rubberized concrete cladding are calculated and the anticollision and vibration reduction effects of rubberized concrete are analysed by additional modal damping ratio,and reasonable implementation plan for anticollision and vibration reduction of real bridge are proposed.

橡胶混凝土是以混凝土为基材，掺入橡胶集料制成的复合材料，橡胶集料的加入不仅改善了混凝土的抗裂性能和延性，使得它具有较强的耗散能力，而且为科学处理废旧轮胎提供了一条新的途径。本课题拟利用理论与试验相结合的方法，从研究橡胶混凝土材料的耗能特性入手，开展其在梁式桥防撞减振中的应用研究。按照从材料到构件再到结构的层级，通过轴向滞回试验获取橡胶混凝土材料的耗能特性及动荷载参数对其耗能特性的影响规律，提出橡胶混凝土材料耗能计算方法；通过普通混凝土构件增加橡胶混凝土覆层的试验，研究覆层材料、覆层设置方式、覆层与原构件厚度比、刚度比等参数对构件自振特性、动力响应特性及抗冲击特性的影响规律，提出利用橡胶混凝土覆层防撞减振的优化设计方法；通过附加模态阻尼比的方法考虑橡胶覆层的影响，对采用橡胶混凝土覆层的梁式桥进行撞击响应和地震响应计算，分析应用橡胶混凝土覆层的防撞减振效果，给出针对实桥的合理防撞减振实施方案。

本课题采用理论与试验相结合的方法，探究了橡胶混凝土材料耗能特性，并对其以覆层形式应用到梁式桥中的防撞减振效果展开研究。首先通过轴向滞回试验获取橡胶混凝土材料的耗能特性及动荷载参数对其耗能特性的影响规律，提出了橡胶混凝土材料耗能计算方法；其次，通过摆锤撞击橡胶混凝土覆层试验，研究覆层材料、覆层设置方式、覆层与原构件厚度比、刚度比等参数对构件自振特性、动力响应特性及抗冲击特性的影响规律，提出利用橡胶混凝土覆层防撞减振的优化设计方法；最后，通过附加模态阻尼比的方法考虑橡胶覆层的影响，对采用橡胶混凝土覆层的梁式桥进行撞击响应和地震响应计算。以此来评价应用橡胶混凝土覆层的防撞减振效果，并针对实桥提出了合理的防撞减振实施方案。研究结果表明，1）橡胶混凝土抗压强度、弹性模量随着橡胶掺量的增加而减小,最终破坏形态呈明显塑性,橡胶掺量对其力学性能影响更大；2）橡胶混凝土阻尼耗能能力明显高于普通混凝土。表现为损耗因子随加载力幅值水平的增大呈线性增长，但随着橡胶粒体积掺量的增加呈现二次函数增长关系。橡胶粒体积掺量比粒径大小对其阻尼耗能能力的影响更大；3）加设具有延性特征的橡胶混凝土覆层可减弱碰撞接触刚度，减小撞击力峰值。橡胶混凝土材料的高阻尼特性能够吸收耗散输入于墩柱的碰撞能量，使墩底应变、墩顶位移和墩身加速度大为减小。此外，随着撞击速度的增加，其阻尼耗能能力有较大幅度的提高。该形式覆层兼顾防撞和抑振的双重效果，可有效保护桥墩，且为废旧轮胎的处理提供了一条绿色有效的途径。