Steel Shear Connections in Composite Frames Subject to Progressive Collapse

  • Author / Creator
  • The susceptibility of structures to extensive collapse when subjected to a localised failure due to an extreme loading event has in recent years gained considerable research attention. The scenario most often used to assess such performance, either experimentally or through finite element simulation, is the loss of a column, requiring the floor system to bridge across two building bays with the aid of arching and catenary actions. When a column is abruptly disengaged by an abnormal load, the resulting double-span beam must bridge over the removed column by developing a new equilibrium path to redistribute the load to the adjacent elements. This severe damage in a steel gravity frame, which is designed to carry primarily gravity loads, creates significant demands on shear connections. The response of steel shear connections as a component of steel gravity composite frame systems under the column removal scenario is still largely unknown due to the complex interaction between the slab and the steel framework at large deflections. While the slab itself can participate in maintaining the integrity of the overall floor system, its presence amplifies the demand on the steel connections after experiencing initial flexural action. This research investigated the behaviour of steel shear connections in composite frames under a simulated progressive collapse scenario. The research objectives, experimental protocols, and the most significant conclusions drawn from test observations are discussed. The present study describes the details of a comprehensive experimental and numerical program that has been completed to assess the behaviour of connections in composite floor construction by evaluating the failure mode, load carrying mechanisms, strength, and ductility of the connections. An experimental program consisting of 17 full-scale physical tests was performed on connections that included shear tabs and double angles. A variety of parameters were considered, including the connection type, connection depth, connection material thickness, and notional beam span. A testing procedure based on the proposed loading protocols was developed and executed on connections to simulate demands and deformations expected in a composite floor system under a column removal scenario. The second part of this research consisted of comprehensive finite element modelling and analysis techniques. Models were validated using the test results. They were also expanded to investigate the effects of critical parameters on the performance of shear connections in composite frames. Detailed three-dimensional prototype simulations were evaluated and compared with the simplified finite element models and physical tests. The overall capacity of the prototype systems was evaluated and compared with the integrity requirements stipulated in current Canadian and US building codes and design guidelines. Design recommendations based on the experiments and finite element models are proposed for calculating the capacity and ductility of shear connections in composite frames when subject to central column removal.

  • Subjects / Keywords
  • Graduation date
    Spring 2016
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
  • Specialization
    • Structural Engineering
  • Supervisor / co-supervisor and their department(s)
  • Examining committee members and their departments
    • Jar, Ben (Department of Mechanical Engineering)
    • Adeeb, Samer (Department of Civil and Environmental Engineering)
    • Liu, Judy (Civil and Construction Engineering, Oregon State University)
    • Chan, Dave (Department of Civil and Environmental Engineering)
    • Cheng, Roger (Department of Civil and Environmental Engineering)