Abstract
The lateral capacity of exterior concrete columns subjected to a blast load is the key factor in the building collapse probability. Due to potentially severe consequences of the collapse, efforts have been made to improve the blast resistance of existing structures. One of the successful approaches is the use of ultra-high-performance-concrete (UHPC) jacketing for retrofitting a building’s columns. The columns on the first floor of a building normally have higher slenderness due to the higher first story. Since an explosion is more likely to take place at the ground level, retrofitting the columns of the lower floors is crucial to improve a building’s blast resistance. Casting a UHPC tube around a circular RC column can increase the moment of inertia of the column and improve the flexural strength. In this study, a retrofitting system consisting of a UHPC layer enclosed by a thin steel jacket is proposed to improve the blast resistance of buildings in service. Most of the previous research is focused on design aspects of blast-resistant columns and retrofitting systems are mostly based on fiber reinforced polymers or steel jackets. A validated FE model is used to investigate the effectiveness of this method. The results showed significant improvement both at the component and building system levels against combined gravity and blast loading.
Highlights
Prevention of progressive collapse due to blast is an important consideration in design of modern buildings and bridges
Columns are the main elements for the stability of a structure and several approaches have been proposed in literature to improve the performance of reinforced concrete (RC) columns under combined axial and extreme lateral loading
Thai et al [14], used a commercial Finite element (FE) analysis code to study the behavior of 250 × 250 × 3600 mm rectangular concrete columns retrofitted with a steel jacket under blast loading having scale distances from 0.10 to 0.40 m/kg1/3
Summary
Prevention of progressive collapse due to blast is an important consideration in design of modern buildings and bridges. Omran and Mollaei [12] performed an experimental and numerical investigation on rectangular RC columns made with normal strength concrete They proposed six different retrofitting schemes based on steel jacketing to improve the blast resistance. The inner steel tube thickness, hollowness ratio, axial load level, and fiber orientation were found to be more effective than the concrete strength and the outer FRP tube thickness in improving the blast-resistance. Thai et al [14], used a commercial FE analysis code to study the behavior of 250 × 250 × 3600 mm rectangular concrete columns retrofitted with a steel jacket under blast loading having scale distances from 0.10 to 0.40 m/kg1/3. Cui et al [15] investigated the damage response of two concrete-filled steel tube columns subjected to near-filed blast loading with a scale distance of 0.14 m/kg1/3.
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