Abang Abdullah Abang Ali

Construction performance comparison between conventional and industrialised building systems in Malaysia

Purpose – Labour usage represents one of the critical elements in the Malaysia construction industry due to severe shortage of local workers. This paper aims to present a construction performance comparison between conventional building systems and industrialised building systems (IBS).Design/methodology/approach – Data were obtained from 100 residential projects through a questionnaire survey in 2005. A total of 100 respondents participated in this study.Findings – Analysis of variance (ANOVA) results indicated that the actual labour productivity comparison between conventional building system and IBS was significantly different. Further, the comparison of crew size indicated that the conventional building system of 22 workers was significantly different from the IBS of 18 workers. Similarly, the cycle time of 17 days per house for conventional building system was found to be significantly different from the IBS of four days. However, the conventional building system was found to be insignificantly diffe...

Development of Nanotechnology in High Performance Concrete

Concrete is the most widely used building material all around the world which has been undergoing many changes aligned with technological advancement. The most recent available type of concrete is high performance concrete which is produced employing different admixtures both chemical and mineral to enhance mechanical and durability qualities. As sustainability emerged as an indispensable factor in concrete industry, many researchers targeted micro sized mineral admixtures such as silica fume, fly ash, rice husk ash, slag and so on in order to replace Portland cement which is known to be responsible for almost 7% of carbon dioxide emission into atmosphere.Recently, technology has made it easy for scientist to study nanoscale admixtures and their effect on structure of concrete. This paper reviews nanomaterials in cement composites and how they can improve different properties of concrete.

Effect of Soft Story on Structural Response of High Rise Buildings

Severe structural damage suffered by several modern buildings during recent earthquakes illustrates the importance of avoiding sudden changes in lateral stiffness and strength. Recent earthquakes that occurred have shown that a large number of existing reinforced concrete buildings are vulnerable to damage or even collapse during a strong earthquake. While damage and collapse due to soft story are most often observed in buildings, they can also be developed in other types of structures. The lower level containing the concrete columns behaved as a soft story in that the columns were unable to provide adequate shear resistance during the earthquake. Usually the most economical way of retrofitting such as a building is by adding proper bracing to soft stories. So, in this paper occurring of soft at the lower level of high rise buildings subjected to earthquake has been studied. Also has been tired to investigate on adding of bracing in various arrangements to structure in order to reduce soft story effect on seismic response of building. It is lead to assess the vulnerability level of existing multi-storied buildings so that they can be retrofitted to possess the minimum requirements. This will help in minimizing the impending damages and catastrophes.

Housing shortage for low-income in Yemen : causes and suggestions.

Purpose – The purpose of this paper is to identify the factors that cause housing shortage for low‐income groups in Yemen and recommend some solutions to alleviate the problem.Design/methodology/approach – A questionnaire survey has been used as the tool to carry out this study. The first part of the questionnaire consisted of three groups namely: economic, administrative, and legal factors. The second part consists of suggestions on housing supply, construction methods, and materials used for low‐cost housing in Yemen. The level of importance of the categories was measured and the relative importance of weightage was ranked.Findings – The results show that the most important economic factors causing housing shortage were poor handling of available economic resources and shortage of economic resources. The most important administrative factors causing housing shortage were lack of organization and synchronization and not conducting studies on housing. The most important legal factor causing housing shorta...

Behavior of high-strength concrete cylinders repaired with CFRP sheets

This study aims to investigate the behavior of damaged high-strength concrete cylinders repaired using carbon fiber reinforced polymer (CFRP) sheet. The experimental work on CFRP-wrapped concrete cylinders with various predamage levels indicated that CFRP can precisely resist the axial aggravated deformation of cylinders caused by damaging under uniaxial loading. The findings also revealed that the energy absorption of the damaged specimens confined with CFRP was restored approximately three times more than that of the undamaged specimens without confinement. Therefore, an empirical relationship exists between the pre-damage levels and the uniaxial compressive strength reduction of the concrete cylinders.

An Overview of Strut-and-Tie Model and its Common Challenges

B-Regions are parts of the structure in which Bernoullis principle of straight-line strain is used. D-Regions are parts of the structure with a complicated variation in strain. In essence, D-Regions contain the parts of structure which are near to the concentrated forces or steep changes in geometry which are so-called geometrical discontinuities or static discontinuities. Strut-and-Tie Model (STM) is one of the best models to analyse the D-regions. Nevertheless, according to the existing literature, there are still some challenges about STM which are addressed in this paper. STM and its details are investigated to show its common challenges presents some recommendations to overcome these challenges. According to this review, the major challenges in STM are related to the strut effectiveness factor, static uncertainties of STM, strain compatibility, and anchorage requirements in STM. The scope of this research is confined to the two dimensional STM.

A simple and practical model for FRP-reinforced cracked beam

In this paper, a numerical method is developed to model tensile crack in a three-point bending concrete beam which is reinforced with fibre-reinforced polymer (FRP). In this method, the energy release rate is estimated by considering fracture process zone (FPZ) and more accurate stiffness. To do so, the depth of the beam, the effective crack and the initial notch are considered in the FPZ length. To improve the accuracy of estimation, a spring element is used to model the cohesive zone. The energy dissipation rate is also calculated using virtual crack closure technique in FRP-reinforced concrete beam and then, the crack propagation criterion is presented. The model is easy and accurate, converges fast and is capable to model the crack growth in FRP-reinforced concrete cracked beam. Also, the model presented in this study shows acceptable similarity to the experimental data used.

A Web-Based Architecture for Interactive Finite Element Program

In the recent decade, using of Personal Digital Assistants (PDAs) and smart phones had incredible growth and they can be used as a small computer in business, communication and education. Most of current civil engineering software are created for desktop computers in specific operating system and platforms without any portability and flexibility feature. This paper proposed a web-based architecture for an interactive Finite Element (FE) program. The architecture supports linear and nonlinear analysis of reinforce concrete buildings subjected to static and dynamic loading. Structure modeling is performed on the client-side via any internet browser. Data is send to the server and analyzed by FE program which has been installed on the server. Then, the result of analysis which is response of structure under imposed load is send back to the client-side to show and plot output of analysis. The developed software which is named Analysis of Reinforced Concrete Structure (ARCS) implemented in secure and user friendly interface. Running software in offline mode is possible for modeling but internet connection is needed to transfer input data to the server and transfer output of analysis from server to the client-side. The most important advantage of proposed model is operating system and platform independency. Backup capability of all data and authority access control are other features of ARCS. Therefore the developed software is able to use extensively by engineers to carry out modeling and analysis of structures by any PDAs or smart phones through any operating systems and platforms.

3 Dimensional Damper Element For Reinforced Concrete Frames

This paper describes the development of a numerical finite element algorithm used for the analysis of reinforced concrete structure equipped with shakes energy absorbing device subjected to earthquake excitation. For this purpose a finite element program code for analysis of reinforced concrete frame buildings is developed. The performance of developed program code is evaluated by analyzing of two reinforced concrete frame buildings model. The results are show that using damper device as seismic energy dissipation system effectively can reduce the structural response of framed structure during earthquake occurrence.

Plain Concrete linearized Stiffness Diminution Modeling Subjected to Different Stresses-Strain Relationship Models

Linearized stiffness diminution, which is correlated with material damage characteristic, is the major parameters due to modeling of granular material behavior such as plain concrete subjected to cyclic loading. Many damage equations in tension and compression states are proposed in the literatures, however, they produces different damages considering the concepts of the equations development without any capability of fitting and calibration of produced damages curves with any arbitrary test records. In the present paper, the new equations of concrete damages in the tension and compression state with calibration capability based on the two separated damage indices are developed based on linear interpolation hypothesis. In the result, it is shown that the present equations can be produced the damage parameters close to experimental data.