Keywords: robustness, building structures, alternate load path method, tying force method, sudden member loss, ductility.

This paper presents two rational methods for the robustness assessment of building structures subject to the sudden loss of a vertical load bearing member. The first is a multi-level assessment framework which offers a practical alternate load path approach based on nonlinear static analysis combined with a simplified dynamic assessment approach. Besides applicability at various levels of structural idealisation, a key feature of the proposed approach is its utilisation of the energy balance principle in simplified dynamic assessment, leading to the notion of the pseudo-static capacity as a rational measure of structural robustness. An important feature of this approach is it application to various types of nonlinear static pushdown response, avoiding prescribed dynamic increase factors which are typically unsafe for a nonlinear static response characterised by tensile catenary/membrane action and/or compressive arching action. The second method is a recently developed simplified tying approach which recognises the inadequacy of the prescriptive tying force requirements originating from the UK Building Regulations and currently considered in the Eurocodes. The new horizontal tying force method recognises the significance of the system deformation capacity, accounts for various types of loading and sources of tying, and allows for dynamic amplification. Moreover, it comes with supplementary methods that consider the interaction of the affected floors system with the surrounding structure. The relative simplicity of the proposed tying force method, which has been validated for different forms of building construction, renders it a suitable for prescriptive tying force requirements in the next generation of the Eurocodes.

download the full-text of this paper (PDF, 7 pages, 535 Kb)

go to the previous paper
go to the next paper
return to the table of contents
return to the volume description