Investigation of Reinforced Concrete Column with Concealed Pipe for Plumbing and Electric Installation using Finite Element Analysis

Abstract

It is known that the ultimate strength and carrying capacity of columns depends on pattern of loading, cross-sectional shape of columns, diameter of reinforcement, and cross-sectional area of the columns. Hollow-core systems are cost effective, allow construction to remain on budget and on schedule, require less maintenance, and create less environmental impact than conventional building materials. Hollow core columns having circular holes shall be better performance as it creates smooth configuration to cross-section of columns. The behavior of reinforced concrete columns with holes under axial load is not understood, and researches in the subject are needed to help designers and structural expert officials. Holes drilled out to install additional services or equipment, such as ducts through columns, beams, or walls, can lead to loss of strength and possible structural failure. Until now little work has been done on effect of holes in columns and, hence, this study aims to examine the amount of capacity and strength lost due to the presence of holes in columns. Nonlinear finite element analysis on 14-columns (7- squares; 7-rectangulars) specimens is conducted by using ABAQUS software. The nonlinear finite element analysis program ABAQUS is used owing to its capabilities to predict either the response of reinforced concrete columns in the post-elastic range or in the ultimate strength range of reinforced concrete columns. An extensive set of parameters is investigated including; dimensions of the holes with diameter of (20mm, 50mm), and different relative position of the holes in the columns. The shapes of holes are circular for both columns. The carrying capacity and ultimate strength of reinforced concrete short-braced columns with different position of longitudinal openings are discussed in the lesson of study. The effect of the electric wiring through the columns with help of ducts are adequately assessed under the effects of axial loading; because the structural response of the members with a hole under pure axial loading may be significantly different from that of solid column due to existence of avoid section. In conclusion, the analysis result shows significant reduction in load carrying capacities for both square and rectangular columns with duct of wiring compare to their respective solid columns due to reduction of their effective cross-sectional area. The study also reveals that, square columns are sensitive in reduction of capacity than rectangular columns of the same size of the holes at the same position in the columns cross-section. For instance, the peak reduction for rectangular column is 5.55 % (case-d) and 7.75 % (case-d) for square columns compare to their respective control specimens.