Experimental Study on the Pre-stressed Underpinning Joints

摘要

The underpinning technology is one of the key procedure in the building moving or uplifting retrofitting.The previous research found the old-new concrete bonding interface is the fragile position for frame structure underpinning joints.Therefore, the pre-stressed underpinning joint was put forward and did some experiments.Eight pre-stressed double-beam underpinning joint specimens and ten four-sides-wrapped pre-stressed underpinning joints and one comparison specimen are tested.The experimental results show that the bearing capacity is higher as the pre-stress value increased and almost obey positive linear relationship with the pre-stress value.On the other hand, pre-stress added on the underpinning beam and coupling beam simultaneously is more suitable which the bearing capacity will increase about 20％ than the pre-stress added on underpinning beam or coupling beam only.