Experimental and Numerical Study on Bolted Web-Flange Steel Connections in Fire

  • Paul Akagwu

Student thesis: Doctoral Thesis


The behaviour of bolted web-flange steel splice connections when exposed to elevated temperatures was studied using experimental and numerical modelling. Failure modes were identified and the major parameters that affect the response of these connections under such extreme loadings were analysed.

Eight bolted web-flange steel splice connections were tested. Six specimens were fastened with M16 bolts and two with M20 bolts. The specimens fastened with M16 failed abruptly by bolt shear with negligible deformations in the splice plate bolt holes. The specimens fastened with M20 bolts however, failed in a more ductile pattern with significant bearing deformation in the bolt holes and shear deformation in the bolts. The observed rotations with the M16 fastened specimens ranged from 75 to 85 mrad, while those for the M20 fastened specimens were within 90 to 100 mrad.

The 3D finite element parametric analyses revealed that from ambient to the mid high temperature ranges the contribution of plate thickness to rotational capacity is more pronounced when compared to the higher temperature ranges.

The temperature - rotation curves obtained from the tests were converted into moment – rotation – temperature curves using the Ramberg-Osgood curve fitting technique and incorporated into Abaqus to enable a more extensive parametric study to be performed. The influence of axial restraint, connection type, temperature gradient amongst others were investigated. The results revealed that the temperature of the connection relative to that of the beam has implications for the behaviour of the beam in fire. Connection temperatures within 40 to 60% of the beam bottom flange temperature could prevent premature failure especially if the beam is expected to enter catenary resistance.
Date of AwardApr 2021
Original languageEnglish
SupervisorFaris Ali (Supervisor) & Ali Nadjai (Supervisor)


  • Finite element
  • Elevated temperature

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