# A Parametric Computational Study of RC Building Structures under Corner-Column Removal Situations
## 1 Introduction  
Progressive collapse is one of the hottest topics in structural engineering [1; 2]. In this field, many researchers have worked on independent-scenario approaches, considering the sudden removal of an element in buildings or bridges to study the consequences of an extreme event rather than studying the triggering causes of a progressive collapse. These approaches can demonstrate (or not) that the structure has a minimum level of robustness and highlight potential areas for improvement, extracting conclusions to increase the resilience of a structure against accidental actions. Research studies to date have concentrated on both computational simulations (e.g., [3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16]) and experimental analysis (e.g., [17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28]), together with studies of real events of progressive collapse [29; 30; 31; 32].  
Few experimental studies are available on reinforced concrete (RC) building structures, particularly on purpose built full-scale structures subjected to sudden removal of columns [28; 33]. Most of the cases studied with sudden column removal have been on subassemblies, including cases involving internal and edge columns (e.g., [PERSON] et al. [34]) and, to a lesser extent, on corner columns (e.g., [35]), although the columns in the latter case are more vulnerable to accidental events [28]. Due tothe small number of tests on full-scale buildings, only a few of the computational models found in the literature have been fully validated.  
The aim of this paper was thus to make a thorough parametric study based on a validated Finite Element (FE) analysis and high performance models of a purpose-built full-scale RC building structure under a corner-column removal situation experimentally tested in a previous work carried out by the authors [28]. This is part of the research significance and novelty of the paper, together with its focus on design accidental situations according to the actual load combinations established in the codes [36; 37; 38] so as to set: (i) Alternative Load Paths (ALPs) activated after the sudden loss of a corner-column, (ii) Dynamic Amplification Factors (DAFs) or Load Increase Factors (LIFs) and (iii) key aspects of building design and recommendations for achieving safe structures. This work is focused on predicting the response to failure of one of the members in the structure after column removal which could trigger progressive collapse; the propagation of failure after this point is not within the scope of this paper.  
The paper is organised as follows: Section 2 contains a description of the study carried out, including the building and the test itself, the FE model, its validation and the parametric study. The results obtained are given in Section 3, while Section 4 contains the discussion on the activation of the ALPs and considers key aspects for the design of robust structures against corner-column removal situations and the definition of the DAFs and LIFs obtained in relation to the parameters studied. The main conclusions are given in Section 5.