Effects of Infills in the Seismic Performance of an RC Factory Building in Pakistan

Abstract

Infilled reinforced concrete (IRC) frames are a very common construction typology, not only in developing countries such as Pakistan but also in southern Europe and Western countries, due to their ease of construction and less technical skills required for the construction. Their performance during past earthquakes has been in some cases satisfactory and in other cases inadequate. Significant effort has been made among researchers to improve such performance, but few have highlighted the influence of construction materials used in the infill walls. In some building codes, infills are still considered as non-structural elements, both in the design of new buildings and, sometimes, in the assessment of existing buildings. This is mainly due to some difficulties in modeling their mechanical behavior and also the large variety of typologies, which are difficult to categorize. Some building codes, for example, Eurocode, already address the influence of infill walls in design, but there is still a lack of homogeneity among different codes. For example, the Pakistan building code (PBC) does not address infills, despite being a common construction technique in the country. Past earthquake survey records show that construction materials and infill types significantly affect the seismic response of buildings, thus highlighting the importance of investigating such parameters. This is the object of this work, where a numerical model for infill walls is introduced, which aims at predicting their failure mode, as a function of some essential parameters, such as the friction coefficient between mortar and brick surface and mortar strength, usually disregarded in previous models. A comprehensive case study is presented of a three-story IRC frame located in the city of Mirpur, Pakistan, hit by an earthquake of magnitude 5.9 on 24 September 2019. The results obtained from the numerical model show good agreement with the damage patterns observed in situ, thus highlighting the importance of correctly modeling the infill walls when seismically designing or assessing Pakistani buildings that make use of this technology.

Studying several parameters on unreinforced masonry infill walls R.C framed structure by SeismoStruct program

“…In lled wall frames improve ductility, stiffness, and energy absorptions of structural systems [5]. The in ll walls can be modeled by different numerical techniques such as micro, meso, and macro modeling [6,7]. In lled frames damage is caused by the serious interaction between masonry in lls and bounding frames.…”

Seismic Performance Target and Fragility of Masonry Infilled RC Frames under In-Plane Loading

“…Masonry infills are one of the most prevalent types of nonstructural elements used in modern architecture buildings in both China and abroad [1]. The existence of infill walls not only changes the stiffness and strength of the structural system and its distribution, but also adversely affects the local restraint conditions of the main structural members [2,3]. The collapse of infill walls can cause significant property damage, and may even affect emergency evacuation and endanger life safety [4][5][6][7][8].…”

Natural-Fibrous Lime-Based Mortar for the Rapid Retrofitting of Masonry Heritage

“…Kashmir 2005, L'Aquila 2009, Christchurch 2011, Emilia 2012, Amatrice 2016). Under earthquake excitation, masonry structures are subjected to multi-directional ground motions, which causes in-plane and out-of-plane loads and eventually provokes their collapse [1][2][3][4][5][6][7][8]. In the last decade, there has been a growing demand in protecting masonry heritages because of decades of studies and investments in this field as well as the necessity to maintain and to pass them to future generations.…”