Kamal Nasharuddin Mustapha

Effective Method of Repairing RC Beam Using Externally Bonded Steel Plate

Repair of reinforced concrete beam with externally bonded steel plate or fibre reinforced polymer (FRP) laminate is becoming both environmentally and economically preferable rather than replacement of deficient beam. The well known advantages of external reinforcement over other methods include; low cost, ease of maintenance and the ability to strengthen part of the structure while it is still in use. The disadvantage of this method, however, is the premature debonding of the externally bonded strips which is brittle and undesired mode of failure. It is also known that debonding of the externally bonded steel plates prevents the reinforced concrete (RC) beam from reaching its full strengthening capacity. The aim of this study was to increase the scientific understanding on the behaviour of damaged reinforced concrete beams strengthened and/or retrofitted for shear using vertical steel plate fixed with adhesive and steel connectors to eliminate or delay debonding failure. Four reinforced concrete beam specimens were prepared to investigate the effects of connectors in preventing or delaying premature debonding of shear strips to restore the capacities of fully damaged beams. Three damaged beams have been repaired and strengthened with steel plates and loaded monotonically up to the maximum load capacities in order to define load–deflection relationship. It is concluded that the repairing of severely shear-damaged RC beams with steel plates by using steel and adhesive connectors can fully restore the original shear capacities of the beams.

Optimization of Structural Design for Sustainable Construction of Transmission Tower Based on Topographical Algorithm

Optimization of transmission tower structures is traditionally based on either optimization of members sizes with fixed topographical shape or based on structural analysis modelling strategies without taking cognizance of fabrication and constructability issue facing the contractors . This paper look into an integrated optimum design approach strategies whereby size, shape and topology are combined together with the fabrication issues in the construction of the transmission tower. The topographical algorithm is based on changing the inclination degree of the legs of the tower at first with optimum individual members sizing and later rationalized member sizes are performed through member groupings for the ease fabrication and construction of the transmission tower. The optimum weight using topographical algorithm obtained for the transmission tower is 10,924 kg for singular members and 18,430 kg for element grouping at 10° inclination angle.

Impact Resistance Performance of Kenaf Fibre Reinforced Concrete

This paper investigate the performance of kenaf fibre mesh reinforced concrete (KFMRC) with varied kenaf fibre mesh reinforcement content for the concrete slab of 300mm × 300mm size reinforced with different mesh diameter at constant spacing with varied slab thickness subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.236 kg drop at 0.40 m height has been used in this research work. The main variables for the study is to find the relationship of the impact resistance against the amount of mesh reinforcement and slab thickness. A linear relationship has been established between first and ultimate crack resistance against kenaf fiber diameters by the experiment. The linear relationship has also been established between the service (first) crack and ultimate crack resistance against the slab thickness. The threshold (highest) values for service crack and ultimate crack is 47.9 N/mm2 and 130.58 N/mm2 respectively observed and computed for 50 mm slab with 7 mm diameter mesh.

A Conceptual Framework for Procurement Decision Making Model to Optimize Supplier Selection: The Case of Malaysian Construction Industry

This paper intends to fathom the current state of procurement system in Malaysia specifically in the construction industry in the aspect of supplier selection. This paper propose a comprehensive study on the supplier selection metrics for infrastructure building, weight the importance of each metrics assigned and to find the relationship between the metrics among initiators, decision makers, buyers and users. With the metrics hierarchy of criteria importance, a supplier selection process can be defined, repeated and audited with lesser complications or difficulties. This will help the field of procurement to improve as this research is able to develop and redefine policies and procedures that have been set in supplier selection. Developing this systematic process will enable optimization of supplier selection and thus increasing the value for every stakeholders as the process of selection is greatly simplified. With a new redefined policy and procedure, it does not only increase the companys effectiveness and profit, but also make it available for the company to reach greater heights in the advancement of procurement in Malaysia.

Impact Resistance Behaviour of Light Weight Rice Husk Concrete with Bamboo Reinforcement

This paper investigate the performance of lightweight rice husk concrete (LWRHC) with varied bamboo reinforcement content for the concrete slab of 300mm × 300mm size reinforced with varied slab thickness subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.236 kg drop at 0.65 m height has been used in this research work. The main variables for the study is to find the relationship of the impact resistance against the amount of bamboo reinforcement and slab thickness. A linear relationship has been established between first and ultimate crack resistance against bamboo diameters and slab thickness by the experiment. The linear relationship has also been established between the service (first) crack and ultimate crack resistance against the bamboo reinforcement diameter and slab thickness. 5% RH content exhibit better first and ultimate crack resistance up to 1.80 times and up to 1.72 times respectively against 10% RH content.

Impact resistance of sustainable construction material using light weight oil palm shells reinforced geogrid concrete slab

This paper investigate the performance of lightweight oil palm shells (OPS) concrete slab with geogrid reinforcement of 300mm ? 300mm size with 20mm, 30mm and 40 mm thick casted with different geogrid orientation and boundary conditions subjected to low impact projectile test. A self-fabricated drop-weight impact test rig with a steel ball weight of 1.2 kg drop at 1 m height has been used in this research work. The main variables for the study is to find the relationship of the impact resistance the slab thickness, boundary conditions and geogrid reinforcement orientation. Test results indicate that the used of the geogrid reinforcement increased the impact resistance under service (first) limit crack up to 5.9 times and at ultimate limit crack up to 20.1 times against the control sample (without geogrid). A good linear relationship has been established between first and ultimate crack resistance against the slab thickness. The orientation of the geogrid has minor significant to the crack resistance of the OPS concrete slab. OPS geogrid reinforced slab has a good crack resistance properties that can be utilized as a sustainable impact resistance construction materials.

Application of Response Surface Methodology in Finite Element Analysis of Deflection of Pretensioned Inverted T-Beam with Web Openings Strengthened with GFRP Laminates

A precast, prestressed concrete girder with circular web openings allows building service systems (mechanical, electrical, communications, and plumbing) to cross the girder line within the member’s depth, reducing a building’s floor -to-floor height and the overall height of the structure. These height reductions have the potential to improve the competitiveness of total precast concrete structures versus other types of building systems. The experimental program reported in this paper tested three inverted -tee girders with circular web openings strengthened with GFRP to failure to evaluate the openings’ effect on girder behavior. The test girders were designed using available recommendations in the existing literature. Using ANSYS, finite element models were developed to simulate beam deflection behavior. Accuracy of the model is assessed by applying it to prestressed beam tested in this research. Comparison of analytical results with the available experimental results for load–deflection relationships show good agreement between the finite element and experimental results. Polynomial mathematical model, generated using various combination parameters using multiple regression analysis were found to be statistically significant. Parametric study using response surface methodology through finite element analysis may form efficient approximation to immediate deflection.

Embedded Connector in Severe Optimization of Steel Plate for Shear Strengthening of RC Beam: Experimental and Numerical Investigations

Environmental impact has become one of the major factors taken into consideration for recent civil engineering studies and projects. Thus, researchers have been concentrating on shear strengthening of existing reinforced concrete structure as an upgrade method instead of demolishing and reconstructing. In general, shear strengthening of RC beams using externally bonded steel plate has gained huge popularity. However, premature debonding of plates is the main drawback of the system, which could be mitigated using embedded connector; thus, the dimension of steel plate could be reduced significantly. Furthermore, numerical analysis on shear strengthening of beams using embedded connector would provide a great insight on the structural behavior. The aim of this research is to severely reduce the dimension of the steel plate using embedded connector for shear strengthening of RC beams and to investigate the performances of optimized shear-strengthened beams through experimental and numerical investigations. The results showed that the dimension of plate was reduced without debonding of the plate if the beam was designed for shear strengthening with the consideration of yield strength of steel plate and shear link. Experimental results showed a maximum increase in failure of 24%. The numerical results predicted accurately the structural performance of beams. The embedded connector had a great effect in deferring and minimizing the debonding failure and accordingly increasing the maximum load of shear failure between 14.5% and 24% compared to control beam.

A New Approach of Shear Connectors to Delay Debonding of CFRP Laminates Used for Shear Strengthening of RС Beams

Shear strengthening of RC beam with adhesively bonded carbon fiber reinforced-polymer (CFRP) laminates is becoming both environmentally and economically more preferable than replacement. However, the early separation of these plated stripes was the most critical failure which leads to prevent reaching the full capacity required from the strengthening. This study aims to present a new method to prevent debonding failure of CFRP laminates adhesively glued to concrete surface using embedded connectors to enhance the interfacial bond strength. Therefore, steel bar and adhesive connectors were fabricated and used at the interface of the bonded CFRP laminates. Five beam specimens including one control beam were tested to investigate the effects of the connectors to prevent or delay the premature debonding of the EB CFRP laminates. The experimental results showed that both steel and adhesive connectors completely prevented premature debonding failure of CFRP shear strip and allowed the beams to fail by flexure with full ductility and strength. Steel and adhesive connectors would enhance 33% and 38% failure loads respectively as compared to strengthened beam without connectors.

An Evaluation on Factors Influencing Decision making for Malaysia Disaster Management: The Confirmatory Factor Analysis Approach

For the past few years, natural disaster has been the subject of debate in disaster management especially in flood disaster. Each year, natural disaster results in significant loss of life, destruction of homes and public infrastructure, and economic hardship. Hence, an effective and efficient flood disaster management would assure non-futile efforts for life saving. The aim of this article is to examine the relationship between approach, decision maker, influence factor, result, and ethic to decision making for flood disaster management in Malaysia. The key elements of decision making in the disaster management were studied based on the literature. Questionnaire surveys were administered among lead agencies at East Coast of Malaysia in the state of Kelantan and Pahang. A total of 307 valid responses had been obtained for further analysis. Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) were carried out to analyse the measurement model involved in the study. The CFA for second-order reflective and first-order reflective measurement model indicates that approach, decision maker, influence factor, result, and ethic have a significant and direct effect on decision making during disaster. The results from this study showed that decision- making during disaster is an important element for disaster management to necessitate a successful collaborative decision making. The measurement model is accepted to proceed with further analysis known as Structural Equation Modeling (SEM) and can be assessed for the future research.