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PurposeThis study provides an integrated risk-based cost and time estimation approach for deep excavation projects. The purpose is to identify the best practices in recent advances of excavation risk analysis (RA) and integrate them with traditional cost and time estimation methods.Design/methodology/approachThe implemented best practices in this research are as follows: (1) fault-tree analysis (FTA) for risk identification (RI); (2) Bayesian belief networks (BBNs), fuzzy comprehensive analysis and Monte Carlo simulation (MCS) for risk analysis; and (3) sensitivity analysis and root-cause analysis (RCA) for risk response planning (RRP). The proposed approach is applied in an actual deep excavation project in Tehran, Iran.FindingsThe results show that the framework proposes a practical approach for integrating the risk management (RM) best practices in the domain of excavation projects with traditional cost and time estimation approaches. The proposed approach can consider the interrelationships between risk events and identify their root causes. Further, the approach engages different stakeholders in the process of RM, which is beneficial for determining risk owners and responsibilities.Originality/valueThis research contributes to the project management body of knowledge by integrating recent RM best practices in deep excavation projects for probabilistic estimation of project time and cost.

In recent earthquakes, the observed collapses have been mainly attributed to inappropriate distributions of stiffness and strength of structural members which result from using inefficient seismic lateral load distribution pattern in design phase. Using nonlinear time history analysis under 88 strong ground motions, this paper investigates the seismic lateral load distribution pattern of 3-, 6-, 12-and 16-story buckling restrained steel braced frames, which have been increasingly used during the past decade. Through comparing analytical results with those predicted by IBC-2009 lateral load distribution equation, it can be concluded that except for low-rise structures, code pattern lateral load is quite different from analytical lateral load pattern in particular for taller structures. Therefore, code pattern lateral load would not necessarily lead to efficient distribution of strength and stiffness within the structure; consequently, the structure does not response in a predictable and desirable manner.