Behavior of beams in bolted column‐tree frames at elevated temperature

Column‐tree moment resisting frames, as the efficient shop‐welded and field‐bolted structural systems, are used in many countries. Very limited research has been carried out on such systems under fire conditions. This paper presents experimental and numerical investigations of the behavior of beam and bolted splice connections in steel column‐tree moment resisting frames exposed to fire. Two full‐scale steel sub‐frames with different splice connections were tested under International Organization for Standardization (ISO 834) fire. The observation of thermal and structural fire behaviors including temperature histories, temperature deflection of the beam, temperature rotation of splice connections, and failure modes was investigated. The beam splice connection failed because of shear fracture of top bolts at temperatures beyond 750 °C, while beam underwent large deflections of more than span/20. In addition, detailed 3‐D finite element models were developed to simulate the structural behavior of the specimens in fire. Obtained numerical results from the finite element analysis successfully simulated the experimental fire test results. Copyright © 2015 John Wiley & Sons, Ltd.