2025/07/30 by MILKESA BERHANU SAKATA
paper · doi:10.20372/nadre:14511
Major Advisor: ENGR. ELMER C. AGON, (ASSO PROF). ABSTRACT Buildings designed in accordance with conventional design codes can lack the robustness necessary to withstand localized damage, as evidenced by a series of events beginning with the Ronan Point apartment building collapse in 1968 and continuing over the next decades (U. Starossek. 2006). Many factors can lead to a collapse of this magnitude, such as design faults, construction problems along with manmade and natural hazards. This variable performance of structures has sparked increased interest and research into progressive collapse analyses for existing and new structures. This study has come up with analysis of low-rise building using beam column sub-assemblage as a protype model for progressive collapse due to middle column loss located at the ground floor through numerical simulation using ABAQUS, (2020) software. the main goal of the model is to come up with simply model and understand the behaviour under large displacement in approximate of collapse. The model contains assembly of two beams and three column stubs representing different parameters such as symmetry and asymmetry beam span, the effect of boundary condition (axial restraint), transverse beam and flexural reinforcement ratio. The impact load that caused column loss is not discussed but the after effect of the loading analysis is performed by a series of finite element analyses for the purpose of achieving the objective of this thesis. The developed model takes into account the structural behavior in terms of applied load vs middle joint displacement (MJD) relationship having impact of bending and arching from both the force and deflection perspectives and damage in concrete at joints. Flexural action following the compressive arching action, catenary action will develop at a considerably large displacement, and this response will assist for progressive collapse analysis. This thesis is made up of five chapters, the first deals with the introduction such as background, statement of problem, objectives, significance, scope and limitation of the study. Followed by literature review on previous researchers, studies and practices in chapter two. The third chapter sort out the methodology used, study variables, source of data, formulation of FEM and validation of the study using experimental data from literature. Chapter four presents results and discussion of the analysis for the developed models. Models having different span length have higher flexural and arching capacity of about 65.18% compared with those having the same span length, but these models fail after CAA where as models having the same span length undergo large deflection before failure. Beam column sub-assembly models with transversal beam have 15.41% flexural capacity and 17.41% compressive arch capacity higher compared with those models without transversal beam. Double reinforced models have 19.94% flexural capacity and 16.23% compressive arch capacity compared with models having transversal beam. In the last chapter conclusions were made concerning the geometer and effects of adjusting the parameters of the model. all proposed models went through the phases of resisting mechanisms, except for asymmetry beam span. models with transversal beam and double reinforcement have relative higher Flexural and arching capacity with relatively small deflection at MJD, the location of maximum damage is at beam column joint where as there is no substantial failure over the length of the beam. The longitudinal side of a beam column sub-assemblage (with the same span) is more resistant to progressive collapse than the lateral side which have asymmetry span. Keywords: Progressive Collapse; Non-Linear Analysis; Finite element method; ABAQUS.