Compressive arch action in beams of steel frames subjected to a column loss

Abstract

Steel frames subjected to a column removal typically exhibit a complex load resisting mechanism characterised by three contributions: i) beam yielding mechanism, ii) compressive arch, and iii) catenary action. The development of compressive arch actions in the beams bridging over the lost column has not been yet thoroughly investigated in steel frames, although such effects proved to significantly contribute to the collapse‐resistance of reinforced concrete frames.This paper aims at shedding light on the compressive arch actions of steel beams in case of column removals accounting for various boundary conditions. Numerical and analytical methods were employed for quantifying the contribution of these effects to the structural robustness of steel frames. A simplified analytical model that allows estimating the magnitude of arching effects in steel beams with various types of end‐connections and horizontal restraints provided by the surrounding structure was introduced. The agreement between numerical and analytical results suggests that the proposed analytical model allows for accurate predictions. This validates the model's use for practical applications and gives promising prospects for its inclusion in consistent analytical methods for predicting the activated alternative load path in steel frames subjected to a column loss scenario.

The FAILNOMORE project – Practice‐oriented design recommendations against progressive collapse in steel and steel‐concrete buildings

“…The longitudinal spring KH,c in Figure 5 represents this relative movement capacity. The geometry and the properties of the beam-to-column joints may also influence the arching effect; this arching effect is discussed in detail by Golea et al [12] in the same Eurosteel 2023 proceedings. From Point (4) to (5) (Phase 3), high displacements are observed in the DAP and therefore second order effects play an important role.…”