Finite element modelling of structural clay brick masonry subjected to axial compression

This Paper Presents The Numerical Verifications Of The Experimental Investigation On The Effect Of Mortar Joint Thickness On Compressive Strength Characteristics Of Axially Loaded Brick-Mortar Prisms. The Three Dimensional Micro Modeling Of The Prisms Was Based On Two Approaches: Firstly, Models Were Assumed To Be Made Of Homogeneous Material; The Second Approach Envisaged The Models As Composite Material Made Of Brick And Mortar. The Later Modeling Approach, Which Assumed The Prism To Be Made Of Composite Material, Gave More Accurate Prediction Of The Stress Distribution In The Prisms, And Also The Failure Loads Predictions Were In Good Agreement With The Experimental Results, Suggesting That This Modeling Approach With Composite Material Assumption Is More Appropriate Than The Homogenous Material Assumption. In The Present Work, A Strength Magnification Factor Has Also Been Proposed For The Design Purposes, Which Can Be Used To Assess The Experimental Compressive Strength Of The Brick Masonry From Its Finite Element Analysis Results

Simulation of Industrialised Building System components production

The construction of IBS building should starts with the production of the IBS components and the production process is the main activity concerned in the IBS production plant. Having an optimum production line to manufacture the required IBS elements within targeted time and limited number of reusable steel mould is very important. In this study, workstation organization method has been adopted in the production of IBS component of beam and column. Witness 2001 simulation software has been used to model and simulate the most optimum production line set up. Here, two production lines set up have been proposed to complete the production of IBS beam and column between two and three months time with limited number of reusable steel mould to supply for the construction of medium size single storey IBS housing project ranging from 100 to 300 units. A contingency production line set up which able to complete the production of required IBS components within a month time with increased number of reusable steel mould has also been proposed. Number of resources such as workstation, tool, storage area and labour has been determined from the proposal. The proposed production line can be applied in the planning and cost estimating of IBS production plant set up

Study on the behaviour of repaired reinforced concrete (RC) concrete elements.

Carbon FRP has recently being used as strengthening elements of reinforced concrete elements such as beams. Two sets of experiments was carried out to study the behaviour beams strengthened with FRP fabric wrap and beams strengthened with FRP plates. The first set consists of 3 beams; a control beam, a beam reinforced with FRP plates, and a pre-cracked beam reinforced with FRP plates. Observations were made on the ultimate load capacity, load-deflection behaviour, crack pattern and propagation of tested beams. Ultimate load capacity of strengthened beams increased by more than 20% when compared to control beam. Strengthened beams also exhibited improved load-deflection behaviour and crack pattern and propagation behaviour. The behaviour of the pre-cracked beam was almost the same as the uncracked beam. The second set of 3 beams was designed with no shear reinforcement so that the beams would fail in shear. Two of the beams were wrapped with FRP fabric wrap while one acts as control. One of the wrapped beams was wrapped with one layer 90o to the horizontal while the other was wrapped with two layers; one at 45o and the other at –45o to the horizontal. Load carrying capacity and load-deflection behaviour of all beams tested were observed. From the results of the experiments it can be seen that the load carrying capacity of the strengthened beams wrapped at 90o to the horizontal almost doubled when compared while the other wrapped beam more than double its load carrying capacity. From the experiments, it is shown that both FRP plates and fabric wrap strengthened beams that were misdesigned or damaged which should encourage their use it the repair of structural elements amongst practitioners

A Novel Approach for Blast-Induced Flyrock Prediction Based on Imperialist Competitive Algorithm and Artificial Neural Network

Flyrock is one of the major disturbances induced by blasting which may cause severe damage to nearby structures. This phenomenon has to be precisely predicted and subsequently controlled through the changing in the blast design to minimize potential risk of blasting. The scope of this study is to predict flyrock induced by blasting through a novel approach based on the combination of imperialist competitive algorithm (ICA) and artificial neural network (ANN). For this purpose, the parameters of 113 blasting operations were accurately recorded and flyrock distances were measured for each operation. By applying the sensitivity analysis, maximum charge per delay and powder factor were determined as the most influential parameters on flyrock. In the light of this analysis, two new empirical predictors were developed to predict flyrock distance. For a comparison purpose, a predeveloped backpropagation (BP) ANN was developed and the results were compared with those of the proposed ICA-ANN model and empirical predictors. The results clearly showed the superiority of the proposed ICA-ANN model in comparison with the proposed BP-ANN model and empirical approaches

Strength characteristic of brown kaolin treated with liquid polymer additives

Kaolin deposits are considered to have poor engineering characteristics, exhibiting expansive properties, high plasticity, poor workability, and low shear strength. This may cause severe damage to civil engineering structures and facilities. Hence, these soils must be treated prior to construction operations, so that desired properties can be achieved. SS 299 is a liquid polymer stabilizers used as a compaction aid or a stabilizer for soil improvement. Yet, it is not used as a common approach when comes to soil stabilization due to its uncertainties in strength improvement when mixed with soils. As a result, laboratory testing programs were conducted to study the strength development of brown kaolin when treated with the liquid polymer with 3%, 6%, 9%, 12% and 15% of soil’s dry mass. The result indicated that the increase in the percentage of SS 299, increases the unconfined compression strength. The maximum value of the unconfined compressive strength of 385 kPa was observed at 15% SS 299 content, cured at 28 days, which was twice the strength of the untreated brown kaolin. The increment of strength was really steep for the first 7 days but the rate decreased thereafter. The optimum content of liquid polymer SS 299 was found as 12%

Liquefaction resistance of sand matrix soils

Numerous researches have been focusing on the roles of fines in liquefaction resistance of sand matrix soils (sand dominant soil that contains little presenting fines). It has been reported that the presence of plastic fines would either imposed additional liquefaction resistance of sand matrix soils or caused reduction to the liquefaction resistance. This paper aims to present the liquefaction resistance of sand matrix soils with respect to different fines content based on the results from cyclic tests using triaxial testing system. The sand matrix soils were reconstituted by mixing the plastic fines (kaolin and bentonite) to the clean sand at seven different percentages by weight. Results showed that liquefaction resistance of sand matrix soils decreases with an increase of fines content until a minimal value and increases thereafter. It was identified that the presence of fine contents to give the minimum liquefaction resistance were 20 % for sand-bentonite mixtures and 25 % for sand-kaolin mixtures. These values represent the threshold fines content for respective mixtures

Surface settlement induced by tunneling in greenfield condition through physical modelling

Geotechnical conditions such as tunnel dimensions, tunneling method and soil type are few factors influencing the ground movement or disturbance. This paper presents the effect of tunnel cover to diameter ratio and relative density of sand on surface settlement induced by tunneling using physical modelling. The aluminum casing with outer diameter of 50 mm was used to model the tunnel shield. The size of the casing was 2 mm diameter larger than the tunnel lining. The tunnel excavation was done by pulling out the tunnel shield at constant speed with a mechanical pulley. The tested variables are cover to diameter ratio (1, 2 and 3) and relative density of sand (30%, 50% and 75%). The results demonstrated that the surface settlement decreased as the relative density increased. Also, as the relative density of sand increased, the overload factor at collapse increased. The surface settlement was at the highest when the cover to diameter ratio was 2. It can be concluded that in greenfield condition, the relative density and cover to diameter ratio affect the surface settlement

Engineering properties of polymer mortar composites in hot humid environment

The understanding of environmental influenced on the properties of polymer mortar composites is still far from complete. This preliminary investigation is to provide some informative data to this unsettle topic. When cured in hot humid environment, it has been observed that the specified compressive strength is obtained as early as 1 day age but the modulus of elasticity is significantly less than the specified values. The flexural strength of polymer mortar composites has been expressed as a function of compressive strength. However, the compressive strength of polymer mortar composites cannot be used as a measure of the modulus of elasticity

A critical review of the reinforced concrete columns and walls concealing rain water pipe in multistorey buildings

Various problems and deficiencies in the strength and load carrying capacity of the reinforced concrete (RC) walls and columns caused by concealing PVC drain pipes within them have been identified. Alternative methods of positioning the drain pipes outside the columns are proposed. An improved method of the present practice has also been suggested. Finally, the research methodology and investigation of this problem which is presently in progress in the Universiti Teknologi Malaysia, Skudai, has been outline

Geotechnical properties of tanjung bin coal ash mixtures for backfill materials in embankment construction

Class F fly ash and bottom ash are the solid residue by-products produced by coal-burning electric utilities. They are usually disposed of together as a waste in utility disposal sites with a typical disposal rate of 80% fly ash and 20% bottom ash. Reutilization of these waste materials in civil engineering applications that require large volumes of fill or back-fill materials, such as embankments and retaining structures, is beneficial. The literature contains only limited information on the use of mixtures of fly and bottom ash in these types of applications. This paper presents a laboratory investigation on the physical properties (grain sizes and specific gravity test), morphology, mineralogy, chemical properties and Mechanical properties (Standard compaction, hydraulic conductivity and strength test) of Tanjung Bin class-F fly and bottom ash mixtures. Six mixtures of fly and bottom ash with different mixture ratios (i.e. 0%, 30%, 50%, 70%, 90% and 100% fly ash content by weight) were prepared for testing. Strength properties of coal ash mixtures are carried out by conducting direct shear test and unconfined compression test. Besides, chemical properties are carried out by XRF analysis. Morphology and mineralogy of coal ash mixtures are studied using scanning electron microscope (SEM) analysis and x-ray diffraction (XRD) analysis. The coal ash mixtures were compacted at 95% of maximum dry density. Morphological analysis showed that the number of irregular shaped particles increased confirming change in material type with different mixture ratios. From mineralogical analysis, the crystalline compounds present in Tanjung Bin coal ash mixtures were quartz, mullite, magnetite, hematite, and calcium oxide. From chemical analysis, Tanjung Bin fly ash is classified as class F in which fly ash has low lime, less than 10%. Its low specific gravity, freely draining nature, ease of compaction, good frictional properties, high shear strength and low compressibility can be gainfully exploited in the construction of embankments, roads, reclamation and fill behind retaining structures