Dynamic response of CFST column with in-plane cross reinforcement and partial CFRP wrapping upon contact blast

Explosions including accidental and manmade too not only cause damage to the structure/building but also inflict severe injuries and loss of human lives around the explosion. Structural damage further aggravates injuries and life loss. Conventional structural design does not include loading from explosion events. Thus few buildings are designed with the requisite resistance against blast loading. Exceptions to this are buildings in petrochemical facilities where explosion hazards exist and high profile buildings such as embassies. The columns of a structure are the basic elements that provide stability and stiffness and carry the loads to the foundation through lateral and gravity load paths. Excessive deflection of a column and its damage may jeopardize the stability leading to disproportionate partial or complete collapse of the structure. This makes the researchers and structural engineers look for improving the performance of key members of a structure under blast loading. In this work, the concrete-filled steel tube (CFST) square column equivalent to an experimentally tested reinforced concrete (RC) column has been considered to improve its anti-blast performance. The seismically reinforced RC column with axial load subjected to an explosive charge of 100 kg ANFO (82 kg-TNT equivalent) at a scaled distance of 1.0 m/kg^1/3 using ABAQUS/Explicit-v.6.15 software equipped with concrete damage plasticity model is validated first. The investigation has been strategized by considering contact blast on columns of (1) steel tube, (2) CFST, and (3) CFST strengthened with in-plane cross-reinforcement, and combined with partial CFRP wrapping of 2 mm thickness over the mid-height region only. Results have been compared with the reference RC column. CFST column shows better performance compared to the steel tube column as well as the reference RC column. Additional in-plane cross-reinforcement to the CFST column improves the displacement and damage response by 42.80% and 22.52%, respectively, with respect to the CFST column without cross-reinforcement. The wrapping applied on the CFST column with the cross-reinforcement further excels the above response by 38.20% and 69.60%, respectively. The novelty of the present work is the tremendous anti-blast performance of the tubular column filled with concrete commonly known as the CFST column as a wise substitute for the conventional RC column, strengthened with in-plane cross-reinforcement and partial CFRP wrapping.