The influences of surface geometry and local soil properties on ground motion are parametrically studied. The system response is numerically evaluated. In the modelling, finite and infinite elements are applied. Three types of topography (single-faced slopes, canyons and ridges) are taken into account. According to the results, topographic conditions, depth of the rigid bedrock and geotechnical properties have significance in the alteration of ground motion at the irregular soil surface and its surroundings. For all selected surface shapes, the most critical cases occur at top corners especially when the slope gets steeper. These cases are independent on the natural period of structures. The results correspond with those earthquakes where topographical effects are observed and could be seemed to be worthwhile from the perspective of earthquake engineering and seismology.

Progressive collapse is defined as the spread of an initial local failure of a structure. This phenomenon, caused by the removal of one or more load-bearing element, is followed by a chain of failures through the structure and ultimately leads to partial or even full collapse of an entire structure. As a result, an accurate understanding of structural behavior subjected to large displacements, caused by progressive collapse, is essential to ensure a safe structural design. A progressive collapse in buildings often starts with the removal of one or more columns and continues with the collapse of adjoining structural elements. Experimental studies on progressive collapse are generally not recommended because of its cost and safety reasons. Today, as a result of progress in computer technology, more complicated problems can be investigated numerically. In this study, a numerical model is used for nonlinear analysis of a reinforced concrete (RC) frame behavior subjected to progressive collapse. It is obtained that there is a good agreement between the results with those of the experimental study given in the literature. According to the results, it can be predicted numerically the response of an RC frame to progressive collapse at a highly accurate level.