Experimental Research On Shear Capacity Of Composite Component Of Double Beams Clipping Wall

With the development of social economy, large quantities of old buildings can not adapt to the needs of the production development. Transformation of the old cities has become a hot issue of common concern to the local governments of China. Reinforced concrete frame structure composed of wide column and double beams is a better approach to solve the problem of restructuring masonry buildings to bulk space ones, in which the role of underpinning technology is crucial, which is not only related to the overall appearance of the buildings and the normal use, but also directly involves the safety of the structure.The double-beams-underpinning is a very important design in underpinning technology. In the underpinning process of masonry buildings, the wall clipped double beams should not be removed, and the rational design of connections can ensure the interaction of double beams and unremoved walls. A reasonable consideration of connecting ribs and the role of wall played on bearing capacity will directly influence the ductility design of "strong shear-weak bending" calculation method.As a part of NSFC(Research on frame structure system of double reinforced concrete beam and wide column in the old masonry underpinning reconstruction),7construction members owned different combination forms and different rib spacing and are designed, including1for the comparison of cast-in-situ concrete beam,3for combination member of unilateral concrete and3for bilateral concrete beam combined structure (i.e. composite member of double beams clipping wall),and static load test is carried on to research the shear performance of members. In this paper, the main work are as follows:1.A connection rib is designed, which can be used as a single hoop directly bearing shearing force.2.Static load tests are done to observe the occurrence, development of bending crack and shearing crack and failure pattern of the experimental beams.3.The results of static load tests are analysed to research the influence of different connection rib spacing and masonry beams on the composite member deflection、the strain of concrete or masonry beams、Longitudinal bar or stirrup and cracking load or ultimate load, the law is summed up.4. Using truss-arch model for reference, A theoretical formula of bearing capacity of composite member of double beams clipping wall is derived, and the similarity of theoretical formula is analysed by comparing with the experimental results.5.Combined with the standard formula of shear bearing capacity of reinforced concrete beams oblique plane, a theoretical formula of bearing capacity of composite member of double beams clipping wall is given, and the similarity of simplified formula is analysed by comparing with the experimental results.