Structural behaviour of Putra block under axial load using FEM

Abstract

Interlocking hollow block (IHB) system is a new building technology which eliminates the mortar layer and instead provides a key connection (protrusions and grooves) to interconnect the blocks. With respect to the mortarless feature of the system, it will shorten the construction period, reduce labour and cost, and is environmental friendly. This study covers the modelling and the analysis of Putra Block which is an interlocking hollow block system developed by the Housing Research Centre at Universiti Putra Malaysia (UPM) under axial compression load using Finite Element Method (FEM). The block units comprise of a stretcher block, a corner block and a half block. The aims of this research were to develop the Putra Block prism model using ABAQUS software and to study the structural behaviour of these prisms under axial load using finite element analysis. The Putra Block prism consists of three layers of blocks where the top and bottom layer are made of stretcher block where the middle layer are made of two half blocks placed side by side. Before proceeding with the simulation study, validation of the Putra Block prisms was conducted by using results from previous experimental research work. It was found that the ultimate load between experimental and simulation results had slight differences with an error of 2.56%. The small variations justify the ability of ABAQUS to predict the structural behaviour of elements under axial compression load with good accuracy level. Based on the FEA study, higher compressive stress value was observed on the face-shell of the block whilst higher tensile stress occurred at the webs. The failure of the prisms was mainly due to extensive tensile cracks induced at the web-shell interaction and middle of the block. Further parametric study reveals that by increasing the height of the individual blocks lead to the reduction of its ultimate load. Consequently, the use of higher concrete grade block indicated an improvement in the prism strength and stability under axial load.