Dr. Lauren K. Stewart

Project Information

PI: Lauren Stewart

Students: Marc Sanborn and Maria Warren

Summary

Explosive threats continue to be a primary tactic of terrorist organizations in today’s international security environment, primarily targeting civil structures and infrastructure. When structures are subjected to blast events, the potential for progressive collapse of the structure due to the loss of load bearing members is a significant concern. A better understanding of the behavior of bolted steel connections before and after extreme loading events is necessary to be able to predict and prevent progressive collapse of structures subjected to extreme loadings. Connections ensure ductility and transfer loads to surviving structural elements after an extreme loading event.

Relatively little experimental research has been done on the behavior of structural bolts under dynamic shear and little research has evaluated the residual shear capacity of bolts or bolted connections after an extreme loading event. The research in this proposal aims to fill that gap with an experimental test program of structural bolts and simple bolted steel connections in shear.

A residual shear capacity experimental test system has been developed to subject ASTM A307 and ASTM A325 structural bolts and bolted connections to an impulsive loading event and then test the residual static capacity of the bolt in an in-situ state. The development of the experimental test system, validation, and preliminary results are presented. The experimental test system can be used to further investigate structural bolts and bolted connections.

The experimental test program will investigate the relationship between an applied impulse and resulting bolt damage. It will also investigate the relationship between an applied impulse and the residual capacity of a structural bolt. Further, the experimental test program will investigate the response of slip-critical connections to impulsive loadings to investigate overall connection behavior. The results from the experimental tests will be used to evaluate the accuracy of current modeling methods. Finally, development of a fast running model using an artificial neural network is proposed to predict the damage and residual capacity of bolts and bolted steel connections subjected to impulsive loadings.

Publications

Sanborn, M. (2018). Experimental methods for understanding the behavior and residual capacity of bolts and steel bolted connections under impulsive loads. Link to dissertation