Dynamic Response Of Single-layer Reticulated Domes Under Fire And Blast Loads

With the development of large-span steel structure design theory and construction technology,there are more and more large-scale venues with large-span steel structures,such as gymnasiums and museums.These large-scale venues are often the focus of the terrorist attacks because of the crowded population.In addition,fires due to management negligence and other causes and the consequent explosions will cause damage to large venues.Therefore,it is of great practical significance to study the dynamic stability of long-span steel structures under the impact of fire-coupled explosion.In this paper,the K8 single-layer spherical reticulated shell model was established by using the finite element simulation software ANSYS.Based on the empirical formula of large space fire temperature rise,the theory of temperature rise of steel under fire and the theory of explosion shock wave propagation,the dynamic response of reticulated shell structure under fire-coupled explosion impact was analyzed.The influence of the parameters such as the ratio of rise to span,roof load,restraint arrangement,cross-section of the shell members,initial defect and span on the dynamic stability of reticulated shell under fire-coupled explosion impact was analyzed.The influence of different fire and explosion locations on the dynamic stability of reticulated shell under fire coupling explosion impact was analyzed.The conclusions are as below:(1)The temperature rise of the reticulated shell members caused by fire has a great influence on their dynamic stability under the impact of the explosion.The critical explosion peak overpressure of the reticulated shell structure decreases with the temperature rise of the reticulated shell members.When the maximum temperature of the reticulated shell members reaches 500? or more,the critical explosion peak overpressure decreases by more than 20%relative to the reticulated shell structure at room temperature.(2)In the range of common ratio of rise to span,given a certain span the anti-blast performance of the larger reticulated shells under fire is better,and it is recommended to use a larger ratio of rise to span.The roof load in the common range is favorable to the explosion resistance of the reticulated shell structure,and the anti-blast performance of the structure increases with the increase of the roof load.The anti-blast performance of the reticulated shells with more constraint arrangement is better.It is suggested that the constraint arrangement should be arranged with the edge node interval or the whole arrangement.The anti-blast performance of the reticulated shell structures with hollow circular cross-section is better than that of reticulated shells with other cross-section shapes.It is recommended to use a hollow circular section.The initial defect has a great influence on the anti-blast performance of the reticulated shell structure.Considering the safety,suggest that the actual critical explosion peak overpressure of the reticulated shell is suggested to be 70%of the ideal critical explosion peak overpressure of the reticulated shell.The span of the reticulated shell determines the internal space of the reticulated shell,so the larger the span,the more the critical explosion TNT equivalent.It is suggested that anti-blast protection measures should be applied to reticulated shells with span below 40m.(3)The location of fire and explosion has a great influence on the critical explosion TNT equivalent of reticulated shell structures.With the location of the fire and explosion point moving from the center point of the reticulated shell to the edge,the critical explosion TNT equivalent of the reticulated shell structure decreases.The critical explosion TNT equivalent of the reticulated shell under fire and explosion located at the edge of the reticulated shell at room temperature is 23%of the critical explosion TNT equivalent of the reticulated shell under fire and explosion located at the center of the reticulated shell at room temperature.The fire and explosion located at the edge of the reticulated shell is a huge threat to the reticulated shell,so it is recommended to strengthen the protection near the edge.