Study On The Residual Bearing Capacity Of The Anchor Embedment And Bond-slip Performance After The Fire

With the rapid development of construction industry in our country, embedded parts are widely used in all kinds of building structure. When the fire broke out, as a key part of the connection of steel structure and concrete structure, the fire resistance of embedded parts is directly related to the overall safety of the structure. In addition, due to the embedded parts that are anchored in the construction phase is difficult to change, the remaining bearing capacity of the embedded parts after the fire will be directly related to post-disaster construction of performance evaluation and reinforcement work. The bonding strength between steel bar and concrete is an important prerequisite for reinforced concrete can work together, the fire influences the mechanical properties of material,at the same time, the bond anchorage performance of steel bar and reinforced concrete can be caused varying degrees of impact, those will be directly related to the overall security of the structure. Therefore, the embedded parts residual bearing capacity after fire and bonding performance between steel bar and reinforced concrete research is necessary.This article mainly includes two parts. One is based on a project example as the background, in view of the construction materials used in engineering, design of69specimens, after the fire test,we had a center pull-out test, obtained the bonding strength between steel and concrete after fire and the τ—s curve, then simply analyzed the degradation mechanism of bond strength. The second is based on the experimental studies of residual bearing capacity of embedded parts after the fire, the corresponding ABAQUS finite element model had been established, obtained the temperature field curve in the whole process of fire and the residual bearing capacity of anchor embedment after the fire, and has carried on the comparative analysis with experimental results.The main conclusions are:After the fire, with the maximum temperature experienced increased, the bond strength of deformed steel bars losses increased significantly. Low temperatures (20-300℃), the loss is10%-25%; Medium temperature (300-500℃), loss of40%-60%; High temperature (500-750℃), the loss is80%-90%; Using finite element software ABAQUS,we obtained the maximum temperature which is generally about10%higher than the value in the test,and the highest temperature appears in the time also in advance than the test results, and about20%in advance,for structure after fire refractory performance analysis, the simulation results of partial security; After the fire, the remaining bearing capacity of anchor embedded parts decline, the tension-shear specimen losses the most, while the specimens were heated for60minutes,the specimens’bearing capacity will decline less than15%, compared with the test results, the simulation result is more conservative, specimens after repair reinforcement can continue to used.The corresponding conclusions in the paper about the bonding performance and the anchor embedments after high temperature have significance for structural member’s fire-resistance design and strengthening after fire.