Study On The Response Characteristics Of Welded Connection Joint Exposed To Fire

As an key component of steel frame structural building, beam-to-column joint plays an important role in maintaining the integrity and stability of the steel structure. Welded connection joint of beam-to-column is widely used in steel frame structural building. It is an important prerequisite and basis for fire-resistant design and fire safety assessment of steel structure to systematically and accurately understand the response of joint exposed to different fire conditions.In this paper the applicability of finite element analysis method which used in welded connection joint research was studied firstly. Then ANYSY was applied to simulate thermal and structural coupling response of welded connection joint exposed to fire. The fire behavior of welded connection joint under different elevated temperature conditions was analyzed. The effect of specific parameters on joint was revealed. The fire-resistance performance of welded connection joint and bolted-and-welded joint was comparative analysis. The effect of fire-resistance performance of welded connection joint in different fire exposure and fire-retardant coating was analyzed. The fire-resistance performance of welded connection joint at cooling phase was exploratory studied. The results indicate that:1. The finite element analysis method had strong applicability in welded connection joint research.2. The elevated temperature curves with different temperature rise rates can significant affect fire-resistance time of welded connection joint in fire. The increase of load ratio will lead to the decrease of limited time under the same fire condition. The welded connection joint with stiffeners can improve fire-resistance time. The fire-resistance of welded connection joint is higher than that bolted-and-welded joint under the same elevated temperature condition.3. The different fire exposure can significant affect fire-resistance performance of welded connection joint, the fire-resistance time of joint?exposed to fire is shorter than that beam-column joint exposed to fire. The different thicknesses of fire-retardant coating can also significant affect fire-resistance performance of welded connection joint, the thicker fire-retardant coating will improve fire-resistance time of joint.4. The different cooling rates can significant affect fire-resistance performance of welded connection joint,?the slower the cooling rate is, the higher the temperature of joint is, and the larger the deformation of joint is, and vice versa. The different temperature rise rates can significant affect fire-resistance performance at cooling phase. The faster the temperature rise rate is, the fire-resistance performance at cooling phase decreased becomes more obvious, and vice versa.All these results offered technical references for fire-resistant design of welded connection joint in steel frame structural building.