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Study on bonded anchors in case of fire

There exist no norms and evaluations to check the fire resistance of bonded anchors. The study on behavior of bonded anchors in fire is conducted at TU Kaiserslautern. The bonded anchors have been used widely in the construction projects as they have high bond strength which can stand long in fire. This study is all about bonded anchors and will be conducted to determine the impact of fire on the bond strength of anchors. The use of FE simulation techniques have significantly increased in the recent years and more often have certain advantages over experimental methods like less computational cost, less economical cost, less man power required and also it is non-hazardous. In visualization the Temperature and stress distribution and crack formation with time advancement are possible. The FE simulations will be conducted using commercial software ANSYS. The material-non linearity and Geometric non-linearity will be considered. The thermal and material properties of steel and concrete can be taken from Eurocodes and of Mortal what provided by manufacturers. The thermal influence of fire can be modeled with natural fire curve according to ISO-834.

Temperature distribution in concrete for different embedded length

In the first stage of the project a parameter study will be conducted for different diameter of steel rod, embedded length of steel rod and the moisture content in concrete. It will help to determine how these parameters affect temperature distribution. Temperature vs. Time and Temperature vs. Length relationships will be compared for Concrete-Steel interface.

Temperature vs Length for different diameter of rebar

In the second stage the temperature distribution will be determined in bonded anchors with mortal filled in between steel rod and concrete. It will give an idea on how the temperature distribution gets affected due to different mortal types. The mortar filled between steel and concrete shall have high resistance to temperature which will maintain its holding capacity in fire. The temperature values measured at concrete-mortar interface will be compared with the previous Temperature values measured at concrete-steel interface.

Tensile load on anchor

Later on the advance thermal-mechanical simulation will be conducted to investigate the crack formation in concrete. For good strength of bond there will be more resistance to tensile load acting on it. The bond strength of anchor is affected by the load and temperature simultaneously acting on it. The mechanical load can be set either constant or time dependent.

 

All the failures associated with bonded anchors under the influence of thermal and mechanical load will be investigated in this study. This work may provide a basis to check the fire resistance of bonded anchors which have not been done yet.