Risk for Progressive Collapse of Seismically Designed RC Framed Structures: Long Side Column Case Adrian G. Marchiș, Mircea D. Botez, and Adrian M. Ioani __________________________________________________________________________________________ Abstract – The present study investigates the risk for progressive collapse of mid-rise RC framed buildings when subjected to damage case C 2 , long side column removal, the most dangerous case for the structures under investigation as the previous study indicates. Four models are designed for three distinct seismic zones from Romania: high, moderate and low. The models located in moderate seismic areas are designed for two ductility classes: medium and high. The step-by-step linear static analysis procedure from GSA 2003 Guidelines is used to establish the potential for progressive collapse. The results show the beneficial influence of the seismic design on the progressive collapse resistance of buildings. In the same time, it was found that the GSA 2003 Guidelines cannot taking into account the positive effect brought by the seismic design when more ductile elements are provided in the structure. Keywords – GSA 2003 Guidelines, progressive collapse, RC framed building, seismic design. __________________________________________________________________________________________ 1. INTRODUCTION Progressive collapse is a situation where local failure of a primary structural component leads to the collapse of adjoining members which, in turn, leads to additional collapse. Hence, the total damage is disproportionate to the original cause [1]. This phenomenon has been an important issue since the partial collapse of the Ronan Point Building, in England, 1968. The attack on the Murrah Federal Building in 1995 and terrorist attacks on September 11, 2001, started a second wave of attention on structural failure and better understanding of progressive collapse [2]. The design philosophy of structures subjected to abnormal loads is to prevent or to mitigate damage, not necessary to avoid the collapse initiation from a specific cause. The U.S Governmental Agency (GSA 2003) provides an independent methodology to assess the potential for progressive collapse of building based on the notional removal of load-bearing elements. Four “missing column” scenarios are specified: the loss of an exterior column located near the middle of the short side (case C 1 ), the loss of an exterior column located near the middle of the long side (case C 2 ), the loss of a corner column (case C 3 ) and the loss of an interior column (case C 4 ). In the linear static analysis the following load combination is considered: Load = 2(DL + 0.25LL) (1) where DL and LL are dead and live loads. The factor of two takes into account the dynamic effect that occurs when the vertical support is instantaneously removed from the structure. The GSA acceptance criteria for the linear static analysis are based, in part, on the DCR (Demand-Capacity-Ratios) concept adopted in FEMA 356 [3]. A. G. Marchiș is with Technical University of Cluj-Napoca, Faculty of Civil Engineeering, Str. C. Daicoviciu, no. 15, 400020-Cluj- Napoca, Romania (e-mail: Adrian.Marchis@mecon.utcluj.ro). M. D. Botez is with Technical University of Cluj-Napoca, Faculty of Civil Engineeering, Str. C. Daicoviciu, no. 15, 400020-Cluj- Napoca, Romania (e-mail: Mircea.Botez@mecon.utcluj.ro). A. M. Ioani is with Technical University of Cluj-Napoca, Faculty of Civil Engineeering, Str. C. Daicoviciu, no. 15, 400020-Cluj- Napoca, Romania (e-mail: ioaniam@yahoo.com).