抗拔不抗剪连接新技术及其应用

New technique and application of uplift-restricted and slip-permitted connection

负弯矩区混凝土板的抗裂难题一直以来制约着钢-混凝土组合结构体系的发展。该文针对这一难题,从组合结构的基本原理出发,提出抗拔不抗剪连接新技术,并研发相应的连接件构造形式,包括滑动式、T型和螺杆式。其中,螺杆式连接件构造简单、施工方便,建议在工程中优先采用。节段模型试验结果表明,抗拔不抗剪新型连接件在几乎不削弱负弯矩区组合梁整体刚度和极限承载力的同时,可显著提高负弯矩区混凝土板的抗裂性能。连接件性能试验还深入揭示了抗拔不抗剪连接件的滑移和抗拔机理。抗拔不抗剪连接新技术已成功应用于组合结构实际工程,解决其抗裂设计难题。抗拔不抗剪理念还可推广应用于提高桥梁上部结构的抗倾覆能力,为改善和加强结构整体牢固性提供新的思路。

Cracking of reinforced concrete( RC) slab at hogging moment regions has always been the critical issue hindering the application of steel-concrete composite structural systems. To address this problem,a new connection concept,called the uplift-restricted and slip-permitted( URSP) connection,is proposed according to the basic theory of composite structures to overcome existing hurdles in cracking resistance. Following this new concept,three types of new URSP connectors( i. e.,sliding-type,T-shape,and screw-type connectors) are developed,and among them,the screwtype connector is recommended as the first choice in actual practice because of its simple details and ease of construction. The section model test indicates that the new URSP connectors can significantly improve the cracking resistance of RC slab at the hogging moment region with the overall stiffness and strength of the composite beam almost unchanged. Through the testing of mechanical properties,the slip and uplift mechanisms of the new URSP connectors are revealed in depth. The URSP connection technique has been successfully applied to several actual composite structures,and has overcome the difficulty in the design of cracking resistance. The URSP connection concept can also be employed to enhance the overturn resistance of bridge superstructures,and offers a new approach for improving and strengthening the structural overall firmness.