Civil Engineering Dimension (E-Journal)
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Modelling the Hydraulic Processes on Constructed Stormwater Wetland
Get PDFConstructed stormwater wetlands are manmade, shallow, and extensively vegetated water bodies which promote runoff volume and peak flow reduction, and also treat stormwater runoff quality. Researchers have noted that treatment processes of runoff in a constructed wetland are influenced by a range of hydraulic factors, which can vary during a rainfall event, and their influence on treatment can also vary as the event progresses. Variation in hydraulic factors during an event can only be generated using a detailed modelling approach, which was adopted in this research by developing a hydraulic conceptual model. The developed model was calibrated using trial and error procedures by comparing the model outflow with the measured field outflow data. The accuracy of the developed model was analyzed using a well-known statistical analysis method developed based on the regression analysis technique. The analysis results show that the developed model is satisfactory
Effect of the Use of Metakaolin Artificial Lightweight Aggregate on the Properties of Structural Lightweight Concrete
Get PDFThis paper investigates the effect of using metakaolin Artificial Lightweight Aggregates (ALWA) as a substitute for coarse aggregates to produce structural lightweight concrete. A combination of 10M NaOH solution and sodium silicate solution was used as alkali activator. The ratio between the metakaolin binder and the alkali activator used in producing metakaolin ALWA is 48%:52%, by mass. It is shown that metakaolin ALWA has higher abrasion and water absorption, and lower bulk density values compared to normal aggregates. To determine the effect of using metakaolin ALWA as coarse aggregates in concrete, three variations of ALWA dosages were used, i.e. 0%, 50%, and 100% of the total coarse aggregates, by volume. The results show that the compressive strength of concrete decreased along with the increase of ALWA content in the mixture. However, concrete using 100% ALWA as coarse aggregates meets the requirements of compressive strength and density of structural light weight concrete
Compressive Strength of Post Fire Exposed Concrete Column Wrapped with Fiber Reinforced Polymer
Get PDFIn this study, behaviour of reinforced concrete columns strengthened using fiber reinforced polymer (FRP; glass fiber and carbon fiber) after fire exposure are discussed. After being exposed to fire as high as 720oC for 180 minutes, the specimens showed concrete and reinforcement strength degradation, even though there was no carbonation. It was found that specimens wrapped by carbon fiber showed better compressive strength but less ductility compared to specimens wrapped by glass fiber. It was also found that the low initial compressive strength did not decrease FRP confinement effectiveness. Increase of wrapped concrete compressive strength was evident despite the low initial strength (<17 MPa). Strength estimation using ACI 440.2R-08 formula, which is originally for wrapped plain concrete without fire heat exposure, underestimated the compressive strength. In the proposed formula, the initial compressive strength (f’co) should be adjusted by considering the modulus elasticity and strain limitation to have more precise estimation.
Spinning Induced Compression Strength of Precast Hollow Concrete Piles
Get PDFPrefabricated precast-hollow concrete pile is widely used as deep foundations due to its several benefits such as the uniformity in concrete quality and its durability. It is also called spun pile since the spinning method is utilized to compact the fresh concrete. During spinning, the fresh concrete is propelled outward due to centrifugal force, which generates a compaction process and develops a hollow in the center of the pile. Several factors, such as the rate of spinning, frequency, and duration of spinning, are affecting the quality of the pile. This paper presents the study of density and compressive strength of spun piles. The specimens were cored from the spun piles with diameter of 800 mm. The results show that the density and the compressive strength of the concrete at outer region of the spun pile are bigger than those at the inner side
Bolt Spacing and End Distance of Bolted Connection of Laminated Veneer Lumber (LVL) Sengon
Get PDFThis paper focuses on bolt connections on Laminated Veneer Lumber (LVL) Sengon. Series of connection tests were conducted to evaluate 3.5d, 5d, and 7d end distances and 3d, 4d, and 5d bolt spacings, where d is a 10 mm bolt diameter. All connections were double-shear model (steel-LVL-steel). The results showed that all variations of end distance failed in ductile manner especially the connections with end distances of 5d and 7d. Load carrying capacity of the connections with end distances of 5d and 7d were about the same. For single bolt connections, those with 5d bolt spacing had the highest ratio of load carrying capacity. Only the two-bolt connections with 5d bolt spacing gave the ratio of load carrying capacity higher than that of prediction. These findings therefore suggests that minimum end distance of 5d and minimum bolt spacing of 5d are recommended to be addopted in LVL Sengon bolted connections
Design and Build: Perception of Project Owners and Contractors on Cost in Java, Indonesia
Get PDFDesign-build (DB) is a project delivery that has already been used widely in USA, UK, Singapore and in other countries. However, it is not widely used in Indonesia and there are limited studies available on DB. The purpose of this paper is to quantify project owners’ and contractors’ opinions about the perceived benefits of DB in terms of cost in Java, Indonesia. The quantitative research design using survey study was conducted to evaluate stakeholders’ opinion on the impact of DB on cost. Survey forms with questionnaires were sent to ten project owners and ten contractors. Inferential statistics using t-test was used to compare the perception between them. The result shows that project owners and contractors agree that DB project delivery has some benefits on cost. However, implementation has to be improved in order for DB to be a preferable project delivery option
A Novel Implementation of Nature-inspired Optimization for Civil Engineering: A Comparative Study of Symbiotic Organisms Search
Get PDFThe increasing numbers of design variables and constraints have made many civil engineering problems significantly more complex and difficult for engineers to resolve in a timely manner. Various optimization models have been developed to address this problem. The present paper introduces Symbiotic Organisms Search (SOS), a new nature-inspired algorithm for solving civil engineering problems. SOS simulates mutualism, commensalism, and parasitism, which are the symbiotic interaction mechanisms that organisms often adopt for survival in the ecosystem. The proposed algorithm is compared with other algorithms recently developed with regard to their respective effectiveness in solving benchmark problems and three civil engineering problems. Simulation results demonstrate that the proposed SOS algorithm is significantly more effective and efficient than the other algorithms tested. The proposed model is a promising tool for assisting civil engineers to make decisions to minimize the expenditure of material and financial resources
Experimental and Theoretical Deflections of Hybrid Composite Sandwich Panel under Four-point Bending Load
Get PDFThis paper presents a comparison of theoretical and experimental deflection of a hybrid sandwich panel under four-point bending load. The paper initially presents few basic equations developed under three-point load, followed by development of model under four-point bending load and a comparative analysis between theoretical and experimental results. It was found that the proposed model for predicting the deflection of hybrid sandwich panels provided fair agreement with the experimental values. Most of the sandwich panels showed theoretical deflection values higher than the experimental values, which is desirable in the design. It was also noticed that the introduction of intermediate layer does not contribute much to reduce the deflection of sandwich panel as the main contributor for the total deflection was the shear deformation of the core that mostly determined by the geometric of the samples and the thickness of the core
Managerial Skills for Managing Construction Safety
Get PDFPrevious research has suggested that self-awareness, visioning, and sincerity are foundational managerial skills for delivering positive safety outcomes in construction projects. This paper aims to verify this finding and to suggest learning approaches for developing these skills in practice. Interviews with experienced construction practitioners were analysed thematically to find common themes. The thematic analysis confirms the necessity of the managerial skills identified in the previous research for managing construction safety and provides directions for construction organisations to improve safety learning. Existing approaches, which mainly adopt the cognitivism learning philosophy, may not be sufficient because the nature of learning in practice aligns with social constructivism, showing that learning occurs informally through interactions with people and artefacts at work instead of in a classroom-structured environment. Furthermore, although learning methods to develop safety skills have been suggested, there remains a need for better statistical evidence of the effectiveness of these methods in delivering safety outcomes
Barriers to Construction Health and Safety Self-regulation: A Scoping Case of Nigeria
Get PDFThis scoping study builds on the recent uncovering that in terms of health and safety (H&S), the Nigerian construction industry is self-regulated in various forms, not unregulated and that the size of company can further explain H&S self-regulation. Consequently, the barriers identified through literature review were assessed using questionnaires. Analysis of the data collected from construction practitioners in Nigeria shows that ‘economic factors’ mostly explains the barriers to construction H&S self-regulation. This is followed by the ‘ability to self-regulate’ and ‘lack of awareness’. Furthermore, the results show significant differences among small, medium and large construction contractors on seven factors of which include ‘normative case’ factors, ‘H&S is a duty’, ‘H&S is the right thing’ and ‘unfair H&S standards or legislation’. Although a scoping study, the study draws attention to the barriers to construction H&S self-regulation in Nigeria and demonstrates an alternative to state regulation of H&S