Experimental study on the effect of lintel on infilled frames under cyclic loading

Abstract

Numerous new and existing reinforced concrete frame structures have unreinforced masonry infill walls, establishing a composite program known as an infilled frame structure. These structures are one of the most extensively exploited structural systems in the world. Identically, these structures are profusely renowned in Bangladesh. However, every year a plethora of natural calamities ensue here and these structures are drastically subjected to cyclic excitation.

In our country, in most of the cases solid clay brick is used in the masonry wall. These buildings composed of solid clay brick perform miserably, especially in cyclic loading. Consequently, alternative material is necessary to address the defects and deficiencies uncovered by previous investigations which resulted in the development of the lightweight perforated clay brick. On the other hand, Lintel has a novel function to transfer loads of the masonry above the opening to the side walls nevertheless; its relevance is totally dismissed in structural design. Hence, these two parameters in infilled frame structure would be interesting to assess.

Four one-story and one-bay infilled frame structures have been constructed at half Scale. Two specimens have been built with solid clay brick masonry (the first one is a normal infilled frame structure and the second one includes lintel connecting one column to another) and the other two have been cast with perforated clay brick masonry (the first one is normal infilled frame structure and the second one includes lintel connecting one column to another). Afterward, they have been subjected to lateral cyclic loading.

From the experiment, it is found that specimens having lintel considerably increase the ductility (52%-81%), ultimate load carrying capacity (7%-23%), and energy dissipation (1.5-5 times). On the other hand, specimens containing perforated clay brick significantly enhance the ductility (10%-30%), and energy dissipation (1.1-4 times).