Evaluation of the amounts of concrete needed to meet stiffness requirements in portal frame buildings with less than seven storeys located in areas of intermediate seismic hazard in Colombia

Abstract

The structural system of reinforced concrete moment-resistant portal frames has been commonly used in buildings constructed in Colombia, due to both functional and technical aspects. Of the latter, extensive knowledge regarding analysis, design and construction is highlighted. Despite its widespread use in the country, this system is characterized by excessive flexibility to horizontal loads, so, in many cases, it is necessary to have large structural elements in order to meet the stiffness requirements stipulated by regulations on earthquake resistant design and construction. This often makes it unfeasible to use this structural system from economic, structural, and architectural points of view. This research, by designing 200 computer models of typical portal frame buildings with occupation listed as standard (group of use I), seismic parameters corresponding to intermediate seismic hazard zones, and variation in height and soil type, demonstrated the quantities of concrete needed per square meter to meet the stiffness requirements stipulated in the Colombian regulations on earthquake resistant constructions (NSR-10). These results allow the design engineer to count on a tool to assess the economic and operational feasibility of using portal frame systems in possible projects to develop, as long as they are within the number of storeys evaluated in this research. Moreover, if the use of the system is considered feasible, a pre-sizing of the structure can be rapidly obtained, considering horizontal effects generally predominant in this type of constructions, to select sections to be used