Study On Tensile Strength Of Steel/CFRP Double Strap Joints Subject To Overload And Hygrothermal Environment

Carbon Fiber Repair Steel Structures technology is a new type, efficient and practical structure Repair technology. Compared with the traditional method of steel structure repair, Pasting CFRP repair steel structure technology has obvious advantages, the application field for bearing capacity of steel structure repair, corrosion fatigue repair and brittleness repair, etc. To make this method get more extensive application in engineering, we must ensure that CFRP and steel structure has good cohesiveness, and the structure in practical engineering, often suffer from fatigue load and the influence of damp and hot environment. Therefore, in this paper, the CFRP reinforcing steel plate bonding interface, and overload damage and tensile bearing capacity of the structure under hot and humid environment erosion is studied, the main research contents and conclusions:(1) Is derived on the basis of Hooke’s law, the bonding interface of CFRP reinforcing steel structure stress calculation formula, at the same time, considering the working condition of two kinds of load and temperature changes, and beg out the middle gap and CFRP plate end calculation formula of maximum shear stress and normal stress. In theoretical calculation, the gap between the bond stresses is greater than the bond stress between the end of outer loading, the gaps in the middle of the bonding interface was destroyed. The theoretical calculation formula parameters analyzed, including rubber thickness and the thickness of CFRP plates and steel plate thickness. Results showed that the maximum stress of bonding interface was increased with the increase of rubber thickness and CFRP plate thickness decrease.(2) For CFRP paste butt plate specimen tensile test study of over damage and the dry-wet circulation two factors, the load and the strain of the component is obtained by tensile test curve, tensile bearing capacity and failure form of the specimens, and analyzes the CFRP and steel plate bonding interface stress distribution rule. Results showed that the maximum stress of bonding interface reduced with the increase of rubber thickness and CFRP plate thickness is reduced, along with the increase with the increase of the thickness of steel plate. Specimen under overload damage and the erosion of the dry-wet circulation, compared with an undamaged specimens, overload damage specimen, dry-wet circulation after the specimen, overload damage and bearing capacity of specimens after dry-wet circulation to reduce rate of18.3%,24.4%and26.5%respectively.(3) Test of tensile bearing capacity with the theoretical calculation results of deviation within15%, the accuracy of theoretical calculation formula is verified. Gaps between cracks first, this is consistent with theoretical calculation, the theoretical calculation of the gaps between the interface stress is greater than the CFRP plate end interface stress. Under tensile load, gaps between cracks, the theoretical calculation of the gaps between the interface stress is greater than the CFRP plate end interface stress.