Experimental Study On Performance Of Bond-Slip Between Steel Shape And Concrete Under High Temperature

Steel reinforced concrete structure with large bearing capacity,good stiffness.good seismic performance and a series of superior performance, therefore is widely used in the construction in modern constructures. With the rapid development of society, fire occurrence frequency of buildings is more and more higher, which has caused great loss and destruction for the human environment and the national economy, so how to ensure the safety of high temperature has become a hot issue in the field of fire resistance of structure.This paper by researching on pushing-out experiment of bond-slip between steel shape and concrete under high temperature, discussed the performance of bond-slip between steel shape and concrete, load and slip value (P-S curve) relation curve, characteristics of steel reinforced concrete and the average bond strength under high temperature in the process of test, analysised main factors affecting the bond -slip between steel shape and concrete under the high temperature, deduced simplified calculation formular of the steel reinforced concrete characteristics of average bond strength under high temperature, providing the reference and suggestions for the practical engineering application.Considering the main influence factors of bond-slip between steel shape and concrete under high temperature:temperature, the compressive strength of concrete, protective layer thickness of steel concrete, embedment length of steel shape in concrete, steel shape of surface in concrete and shape steel concrete stirrup ratio, design of the 27 components; menwhile, considering high temperature steel flange and web of difference for the bond strength of steel reinforced concrete, also designed two group contrast member,2 member of each group to avoid discreteness in the testing process; the whole high temperature type experiment design of component 31 push out of steel and concrete.This paper summarized three characteristics of stage test:the initial slip state, the ultimate slip sliding state and residual state. During the push-out test, detailed observation and recorded the steel shape up loading and the free down slip, the load, crack development characteristics of component, got the push-out test constitutive slip relationship-the load slip curves. The whole test process is comprehensively analyzed, discussing the the change regulation of steel shape and concrete on bond -slip under high temperature.By researching push-out test results of 31 steel reinforced concrete members under high temperature, this paper drawed all the members P-S relationship curve in the process of test. According to test data, analysised the difference of temperature, the compressive strength of concrete in high temperature, protective layer thickness of steel concrete, embedment length of steel shape in concrete, steel shape of surface in concrete and shape steel concrete stirrup ratio.By using the method of linear regression, deduced the simplified formula of average bond strength characteristics of linear regression statistics of various factors. On the basis of that, summarized and considered the correlation of each factor for all test data, deducing the calculation formula for the simplified bonding strength of the SRC in the high temperature.