为给横向混凝土挡块的设计提供明确的依据和参考，以Kelvin模型和Hertz模型为基础，考虑梁体和挡块质量以及二者在碰撞前相对速度的影响，根据动能定理和动量守恒，提出碰撞刚度的计算方法；在此基础上考虑地震作用下主梁与横向挡块间的碰撞效应，分析挡块的初始间隙、高度、厚度等设计参数对墩身、盖梁及挡块自身受力的影响规律。以在满足挡块对墩梁相对位移限制作用的同时，尽可能控制墩身剪力为挡块的设计原则，给出了挡块主要设计参数的建议取值。研究结果表明：设置横向挡块能有效防止落梁震害的发生；随着挡块间隙的逐渐变大，墩身的剪力总体呈减小趋势，碰撞效应减弱；过渡墩的支座滑移距离随挡块初始间隙的增大而增大；挡块厚度和高度对墩底剪力的影响均较小，但对盖梁应力的影响较大，盖梁应力随着挡块厚度的增加而减小，随着挡块高度的增加而增加，当挡块高度达到一定数值时，盖梁的最大拉应力可能超过其最大抵抗应力而破坏；挡块与主梁的初始间隙以0.06 m左右为宜，挡块高度可在0.55~0.65 m取值，挡块厚度在0.48~0.58 m内取值，根据以上参数设置的混凝土挡块，碰撞时最大拉应力可能超过混凝土的抗拉强度而开裂，但受压区混凝土不发生破坏，钢筋的应力亦不超过钢筋的屈服强度，满足挡块承载力的设计要求。
Abstract
To provide a reliable design reference for the transverse concrete block, a collision stiffness calculation method based on the Kelvin model and the Hertz model was put forward in consideration of the mass of the girder and block as well as the influence of relative velocity before the collision. The theorem of kinetic energy and conservation of momentum were considered as the theoretical basis. Considering the collision effect between the main girder and the transverse concrete block during the earthquake, the influence of the initial gap size, height and thickness on the force of the pier, the cover beam and the block was analyzed. A design principle was related to controlling the shearing force of the pier and satisfying the displacement limitation of the relative displacement between the main girder and the pier. The results show that the transverse block can effectively prevent the girder dropping. With the increasing gap size of the block, the shearing force of the pier body gently decreases. Moreover, the collision effect is weakened with the decreasing slipping distance of the transition pier. The influence of the block thickness and height on the shearing force at the pier bottom is slight, but it has a great influence on the stress of the cover beam. The stress of the cover beam decreases with the increase of the thickness of the block and the decrease of the height of the block. The maximum tensile stress of the cover beam may exceed its maximum resistance stress when the block height reaches a certain value. Furthermore, the main design parameters of the block are given as follows:the initial gap size is 0.06 m; the block height can be between 0.55 m and 0.65 m; the block thickness in the range of 0.48 m to 0.58 m. Using above mentioned parameters set for the concrete block, the maximum tensile stress at the time of collision may exceed the tensile strength of concrete to crack, while there is no damage on the concrete in the compression area. Meantime the stress of the steel bar may not exceed the yield strength of the steel, which satisfies the block capacity design requirements.
关键词
桥梁工程 /
横向挡块 /
碰撞模型 /
碰撞刚度 /
挡块设计参数
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Key words
bridge engineering /
transverse concrete block /
collision model /
collision stiffness /
design parameter of transverse concrete block
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中图分类号：
U441.5
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脚注
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基金
国家重点研发计划项目（2017YFC0703400）；国家自然科学基金项目（51778289）；江苏省科技支撑计划项目（BE2014716）
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