Civil Engineering Dimension

Characteristics of PVC Coated Welded Wire Mesh Fiber Reinforced Concrete

2019-04-30T15:10:47+00:00

Introducing fibers into concrete aims to improve the low tensile strength of concrete and its brittle properties. In this research, readily available PVC coated welded wire mesh with diameter of 1 mm was used as fibers in concrete. There are several variations of concrete samples prepared for this study, i.e. based on the fiberâ€™s volume fraction, length and interlocking schemes. Concrete samples were subjected to tensile and compressive strength, and elastic modulus tests. The results show that the incorporation of PVC coated welded wire mesh slightly increases the tensile strength of concrete, with the optimum fiber volume fraction of 1.5%; with the fiber length of 3.6 cm, and with the interlocking of 1.2 cm. However, the concrete compressive strength is slightly reduced, compared to the normal ones. The presence of PVC coated welded wire mesh as fiber also tends to reduce the elastic modulus of fiber reinforced concrete.

Performance Evaluation of Hot Mixture Asphalt Using Concentrated Rubber Latex, Rubber Compound and Synthetic Polymer as Modifier

2019-04-30T10:31:06+00:00

Research on the utilization of natural rubber for Hot Mixture Asphalt as modifier has been widely carried out, and more intensively since 2016 due to the declining global natural rubber price. Further research conducted is the utilization of pre-vulcanized concentrated rubber latex and rubber compound added with antioxidants and treated through vulcanization process. This study experimentally evaluates the performance of Asphalt Concrete Wearing Course (ACWC) using natural rubber and synthetic polymer as modifier, compared to ACWC without modifier (only petroleum asphalt). Â The results show that the rubberized asphalt has higher index penetration value as well as higher elasticity compared to petroleum asphalt penetration grade 60, but lower than synthetic polymer modified asphalt. Similarly, the level of performance of rubberized asphalt mixtures, particularly resilient modulus, water resistance, deformation, and fatigue cracking, is between that of petroleum asphalt and synthetic polymer modified asphalt

Eco Drainage System for Surface Runoff Reduction in Indonesia

2019-04-30T10:31:06+00:00

Sustainable urban drainage systems (SUDS) or eco-drainage system has been implemented in developed countries. The aims of the construction of the system are: to minimize surface runoff by capturing and temporarily retain it, to improve the quality of surface runoff, to infiltrate stormwater, to increase evapotranspiration, and to enhance landscape aesthetic value. Learning from the success of the implementation of SUDS in developed countries, the paper presents a model of eco-drainage system for residential area in Indonesia, which consists of rainwater harvesting system (RWHS) and retention ponds. A simulation of stormwater and surface runoff utilization is also presented. At 14,602.26 m² bare land in Mojokerto Regency, East Java, which is transformed into residential area, the model of eco-drainage system could reduce surface runoff volume almost by 70%. It is recommended to adjust the dimension of rainwater storage tank and retention ponds in order to reduce more surface runoff volume.

Impact of Earthquakes on the Transportation Infrastructure of Indonesia: A Preliminary Study

2019-04-30T10:31:06+00:00

Indonesia is a high seismic region and one of the most vulnerable countries prone to experiencing damaging earthquakes. It is critical that lifeline infrastructure remain operational or is quickly remediated after an earthquake to minimise physical, social, and economical losses. Not much work has been carried out in understanding the effect of earthquakes on transportation infrastructure systems. This study aims to gain a better understanding of the impact of earthquakes on the transportation infrastructure in Indonesia. This is achieved by firstly reviewing the frameworks and tools for conducting seismic risk assessment of lifeline infrastructure. The critical components of the transportation system are then identified. Various forms of transportation infrastructure damage caused by earthquakes are discussed. An overview of the damaging earthquakes for the past 20 years is presented. Finally, conclusions and recommendations are provided about the future work required for conducting risk assessment of the transportation infrastructure in Indonesia

Proposed Design Philosophy for Seismic-Resistant Buildings

2019-04-30T10:31:06+00:00

Modern seismic design and technologies have undergone tremendous developments. In modern design codes, building structures subjected to high earthquake loads are allowed to experience plastic deformations without collapsing, and the design is permitted up to the ultimate strength. According to comparative results in Japan, the number of humans injured due to earthquakes is higher than the number of deaths/missing. Likewise, the number of residential buildings that collapsed are less than the partially damaged buildings. This outcome implies that residential buildings designed based on the revised seismic standards have good earthquake resistances. It also infers that the human deaths/injury casualties were not a result of the collapsed the structure, but due to the strong vibrations originated from the earthquake, yielding in the collapse of non-structural elements such as ceilings and bookshelves. This paper presents a proposed design philosophy that attempts to implement the effect of earthquakes to non-fatal human casualties

Monitoring the Shear Fatigue Response of Reinforced Concrete Beams Subjected to Moving Loads using Digital Image Correlation

2019-04-30T10:31:06+00:00

A series of three reinforced concrete beams without shear reinforcement were tested to failure under a centre-span monotonic load, a centre-span pulsating load, and a stepwise-moving pulsating load. During each experiment, load-deflection response was continuously monitored and at several stages during the experiment, the load was briefly stopped for crack observations. In addition to this manual crack mapping, more detailed crack mappings were undertaken using the digital image correlation (DIC) technique, employing the open-source DIC software Ncorr. It was shown that while the three beams exhibited a similar mode of failure (i.e. shear), each beam displayed a rather distinctive overall behaviour, particularly with regard to the load-deflection response and the nature of crack initiation and propagation. Results from the DIC analysis are presented to provide direct evidence on the damage progression during the load cycles and discuss the reduced fatigue life exhibited by the beam subjected to stepwise-moving pulsating load

The Correlation between Penetration Pressure Required to Install Pile Foundation and to Insert Bi-cones in Cone Penetration Test

2019-04-30T10:31:06+00:00

One of the common methods used to install pile foundation is hydraulic jacked-in machine. In this method, a pile is pushed down into the ground up to the predetermined depth. The method has similar principle to that of Cone Penetration Test (CPT). This paper presents the correlation between the mobilize pressure required to install pile foundations and that required to push the bi-cones that attached at the tip of CPT rod. The results show that the penetration pressure required to install the pile into very soft clay layer is independent of pile diameter. The penetration pressure required to install the pile into soft to stiff clay layers depends on the pile diameter. The larger the diameter of piles, the smaller the penetration pressures required. The penetration pressure required to install the pile into stiff expansive clay layer beyond the depth of active zone can be predicted as high as the pressure calculated form CPT.

Optimization of resource leveling problem under multiple objective criteria using a symbiotic organisms search

2019-04-30T10:31:06+00:00

Bad scheduling and resource management can cause delays or cost overruns. Optimization in solving resource leveling is necessary to avoid those problems. Several objective criteria are used to solve resource leveling. Each of them has the same objective, which is to reduce the fluctuation of resource demand of the project. This study compares the performance of particle swarm optimization (PSO) and symbiotic organisms search (SOS) in solving resource leveling problems using separate objective functions in order to find which one produces a better solution. The results show that SOS produced a better solution than PSO, and one objective function is better in solving resource leveling than the others.

A Comparative Study on Bio-Inspired Algorithms in Layout Optimization of Construction Site Facilities

2018-10-08T10:39:21+00:00

A good arrangement of site layout on a construction project is a fundamental component of the projectâ€™s efficiency. Optimization on site layout is necessary in order to reduce the transportation cost of resources or personnel between facilities. Recently, the use of bio-inspired algorithms has received considerable critical attention in solving the engineering optimization problem. These methods have consistently provided better performance than traditional mathematical-based methods to a variety of engineering problems. This study compares the performance of particle swarm optimization (PSO), artificial bee colony (ABC), and symbiotic organisms search (SOS) algorithms in optimizing site layout planning problems. Three real-world case studies of layout optimization problems have been used in this study. The results show that SOS has a better performance in comparison to the other algorithms. Thus, this study provides useful insights to construction practitioners in the industry who are involved in dealing with optimization problems

Initial Surface Absorption of Cement Combination Concrete

2019-01-22T10:05:33+00:00

This paper investigated the initial surface absorption (ISAT) of concrete using Portland cement (PC) and some binary and ternary cement combinations containing fly ash (FA), silica fume (SF) and metakaolin (MK) as partial replacements for PC at equal water/ cement ratios and strengths. At equal water/cement ratios, the cement combination concretes have higher ISAT values than PC concrete at 28 days and the disparity reduced with increasing curing age due to improved pozzolanic reactivity of the supplementary cementitious materials. SF and MK as binary and ternary cement components performed better than FA due to their higher fineness, improved particle packing and higher pozzolanic reactivity. At equal strengths, FA binary cement concretes have the lowest ISAT values and these reduced with increasing content of FA. At total replacement levels more than 20%, all the ternary cement concretes have lower ISAT values than PC concrete and the values reduced with increasing total replacement level due to the beneficial effect of FA.

Improving Shear Strength Parameters of Sandy Soil using Enzyme-Mediated Calcite Precipitation Technique

2018-10-08T10:39:21+00:00

Several methods have been established for their various potential applications as soil improvement technique, and recently the application of grouting technique using biological process have been proposed. This study discussed the applicability of enzyme-mediated calcite precipitation (EMCP) in improving the shear strength parameters of sandy soil.Â In this study, soil specimens were prepared and treated with the grouting solutions composed of urea, calcium chloride, magnesium sulfate and enzyme of urease. Evolutions in the cohesion and internal friction angle of the improved soil were examined through the direct shear tests. The presence of the precipitated materials, comprising 4.1 percent of the soil mass of the treated sand, generated a cohesion of 53 kPa. However, contrary to the improvement of cohesion, the friction angle is relatively constant. It indicated that the application of the EMCP technique has no significant impact on the friction angle

Seismic Performance of Existing Building Retrofitted with VSL-Gensui Damper

2018-10-08T10:39:21+00:00

Buildings designed using older code should be checked against the higher demand required by newer code. In this study, performance of Building T of Petra Christian University, Surabaya, Indonesia, which was designed with older Indonesian Seismic Code (PPTGIUG 1983) is investigated. The effectiveness of VSL-Gensui Damper application is also investigated as an effort to enhance the performance of the building. Nonlinear time history analysis was conducted to analyze the building. Spectrum consistent ground acceleration generated from El Centro 18 May 1940 North-South component in accordance to current seismic code was used for analysis. The result shows that the existing building cannot resist the demand specified by current code (SNI 1726:2012) as some frame element failures are detected. The performance is greatly enhanced after installation of VSL-Gensui Dampers. Roof story drift and displacement decreased as much as 9% and 14%, respectively as compared to existing building, and structural element failures were no longer observed.

Considering the Effect of Motorcyclist Risk Tolerance in Accident Risk Management: A Preliminary Study

2018-10-08T10:39:20+00:00

Negative perceptions about accident are usually associated with speeding behavior. However, risk perception has not been considered in accident risk management. It is accepted as a personality matter, thus the number of accidents per year was used as accident risk tolerance indicator. Consequently, due to insufficient measurable indicators, it would be difficult to prevent the increasing speeding behavior. This paper discusses the improvement of accident risk tolerance indicators, i.e. safety factor and margin of safety, and their possible usage in speed management policies. These indicators were built based on the correlation between the results of interview and braking maneuver test. From this combine approach, using aggregated-individual and expert acceptance models, it was found that risk tolerance arose because motorcyclists accepted both the advantages and disadvantages gained from speeding, obtained through their riding frequency, duration of riding and/or accident involvement experienced. However, inappropriate speed due to miss-perception toward braking capability should be avoided. Inversely, an appropriate speed management should consider their travelling expectation

Displacement and Stress Function-based Linear and Quadratic Triangular Elements for Saint-Venant Torsional Problems

2018-10-08T10:39:20+00:00

Torsional problems commonly arise in frame structural members subjected to unsymÂmetrical loading. Saint-Venant proposed a semi inverse method to develop the exact theory of torsional bars of general cross sections. However, the solution to the problem using an analytical method for a complicated cross section is cumbersome. This paper presents the adoption of the Saint-Venant theory to develop a simple finite element program based on the displacement and stress function approaches using the standard linear and quadratic triangular elements. The displacement based approach is capable of evaluating torsional rigidity and shear stress distribution of homogeneous and nonhomogeneous; isotropic, orthotropic, and anisotropic materials; in singly and multiply-connected sections.Â On the other hand, applications of the stress function approach are limited to the case of singly-connected isotropic sections only, due to the complexity on the boundary conditions. The results show that both approaches converge to exact solutions with high degree of accuracy.

One Dimensional Site Response Analysis of Liquefaction Potential along Coastal Area of Bengkulu City, Indonesia

2018-10-08T10:39:20+00:00

This paper presents one dimensional non-linear site response analysis of liquefaction potential caused by the 2000 and the 2007 earthquakes in coastal area of Bengkulu City, Bengkulu, Indonesia. Site investigations, including Standard Penetration Test (SPT) and shear wave velocity (V_S) measurement, were conducted in three locations along the coastal area of Bengkulu City. Further, the site investigation data were used in simulation of one-dimensional non-linear site response analysis by applying the synthetic ground motions at bedrock. The results show that liquefaction could happen at 0 to 1.5 m deep. This was indicated by the excess pore water pressure ratio (r_u) which exceeded one. At depth between 1.5 m and 20 m, the excess pore water pressure almost reached the initial effective stress decreasing the effective confinement pressure close to zero. The results also indicated that liquefaction is possible to occur in this depth range if a stronger earthquake occurs.

Influence of Particle Size Distribution of High Calcium Fly Ash on HVFA Mortar Properties

2018-10-08T10:39:20+00:00

This study evaluates the effect of particle size distribution (PSD) of high calcium fly ash on high volume fly ash (HVFA) mortar characteristics. Four PSD variations of high calcium fly ash used were: unclassified fly ash and fly ash passing sieve No. 200, No. 325 and No. 400, respectively. The fly ash replacement ratio of the cementitious material ranged between 50-70%. The results show that with smaller fly ash particles size and higher levels of fly ash replacement, the workability of the mixture was increased with longer setting time. There was an increase in mortar compressive strength with finer fly ash particle size, compared to those with unclassified ones, with the highest strength was found at those with fly ash passing mesh No. 325. The increase was found due to better compactability of the mixture. Higher fly ash replacement reduced the mortarâ€™s compressive strength, however, the rate was reduced when finer fly ash particles was used.

Evaluation of a Reinforced Concrete Wall Macroscopic Model for Coupled Nonlinear Shear-Flexure Interaction Response

2018-04-10T09:44:02+00:00

Reinforced concrete shear wall (RC wall) is an important element in tall buildings, which provides strength and stiffness against lateral loadings, e.g. earthquake and wind. Numerous researches have been conducted to study its nonlinear behavior via microscopic and macroscopic model. The later approach is currently being widely explored since it has many advantages compared to the preceding models. A well-known macroscopic model, namely Shear-Flexure-Interaction Multiple-Vertical-Line-Elements-Model (SFI-MVLEM) in the open source platform Open Sees, is capable of simulating the coupled nonlinear shear-flexure interaction response in the RC wall. This paper presents an evaluation to the applicability of SFI-MVLEM model to predict the coupled nonlinear shear-flexure behavior of RC wall specimens compared to experimental results in available literature. The analysis results show that the model is able to predict the behavior of RC wall considerably accurate in terms of hysteretic curves, cracking patterns, and contributions of shear and flexural displacement to total displacement.

Performance of an Existing Reinforced Concrete Building Designed in Accordance to Older Indonesian Seismic Code: A Case Study for a Hotel in Kupang, Indonesia

2018-04-10T09:43:29+00:00

The recent seismic code SNI 1726-2012 is significantly different compared to the older code SNI 1726-2002. The seismic hazard map was significantly changed and the level of maximum considered earthquake was significantly increased. Therefore, buildings designed according to outdated code may not resist the higher demand required by newer code. In this study, seismic performance of Hotel X in Kupang, Indonesia which was designed based on SNI-1726-2002 is investigated. The structure was analyzed using Nonlinear Time History Analysis. The seismic load used was a spectrum consistent ground acceleration generated from El-Centro 18 May 1940 North-South component in accordance to SNI 1726-2012. The results show that Hotel X can resist maximum considered earthquake required by SNI 1726-2012. The maximum drift ratio is 0.81% which is lower than the limit set by FEMA 356-2000 (2%). Plastic hinge damage level is also lower than the allowance in ACMC 2001.

Wave Trajectory Study on the Coast of Lhoknga, Aceh Besar, Indonesia: A Numerical Model Approach

2018-04-10T09:42:50+00:00

A numerical model of wave trajectory using shoaling and refraction formula was proposed in the coastal waters of Lhoknga, Aceh Besar, Indonesia. The developed model used a two dimensional (2D) numerical methods for wave trajectory with the input of wave height and period; 0.62 m and 8 second for high tide and 0.47 m and 6 second for low tide. This model was tested on site during low tide and high tide conditions for verification. The purpose of this numerical study is to trace the distribution of wave trajectory because of shoaling, wave breaking, and wave refraction. The model determines the wave height and crest pattern of the ray wave trajectory. The simulation result shows the pattern of the wave propagation at Lhoknga beach moves from the northwest to the east and south of the coast. The model also informs that the maximum wave height during high tide condition is 1.72 m and 1.31 m during low tide condition. The result indicates that the coast of Lhoknga has moderate wave conditions caused by a gentle beach bathymetry slope.

Metaheuristic-Based Machine Learning System for Prediction of Compressive Strength based on Concrete Mixture Properties and Early-Age Strength Test Results

2018-04-10T09:42:00+00:00

Estimating the accurate concrete strength has become a critical issue in civil engiÂneerÂing. The 28-day concrete cylinder test results depict the concrete's characteristic strength which was prepared and cast as part of the concrete work on the project. Waiting 28 days is important to guarantee the quality control of the procedure, even though it is a slow process. This research develops an advanced machine learning method to forecast the concrete compressive strength using the concrete mix proportion and early-age strength test results. Thirty-eight historical cases in total were used to create the intelligence prediction method. The results obtained indicate the effectiveness of the advanced hybrid machine learning strategy in forecasting the strength of the concrete with a comparatively high degree of accuracy calculated using 4 error indicators. As a result, the suggested study can provide a great advantage for construction project managers in decision-making procedures that depend on early strength results of the tests.

Stabilising Potential of Sawdust Lignin based Extracts in Compressed Lateritic Bricks

2018-04-10T09:41:23+00:00

Lignocellulosic materials are abundant in nature, rich in some functional groups, considered less harmful to human health and the environment.The resulting waste may be recycled for other beneficial uses. Lignin is known to be a natural binder in lignocellulosic materials and several studies have confirmed it has binding ability with soil particles. This paper studied its stabilising potential in compressed lateritic bricks, especially its effects on density and compressive strength properties of the bricks. Lignin additives extracted from sawdust were used to stabilise laterite, while the bricks were moulded with the UNIFE ram, a type of the CINVA ram. The laterite was stabilised at 4%, 8% and 12%, while cement stabilised samples and 0% (unstabilised laterite) samples prepared accordingly were used as controls. The results showed that the LBAs contributed to the strength gained by the bricks at 3, 7, 14 and 28 days air curing, while the bricks samples were categorised as high density.

Development of the DKMQ Element for Analysis of Composite Laminated Folded Plate Structures

2018-04-19T08:04:33+00:00

The discrete-Kirchhoff Mindlin quadrilateral (DKMQ) element has recently been developed for analysis of composite laminated plates. This paper presents further development of the DKMQ for analysis of composite laminated folded plates. In this development, a local coordinate system is set up for each element at its centroid. The DKMQ stiffness matrix is superimposed with that of the standard four-node plane stress quadrilateral element to obtain a 24-by-24 folded plate stiffness matrix in the local coordinate system. To avoid singularity of the stiffness matrix, a small stiffness coefficient is added in the entries corresponding to the drilling degrees of freedom. The local stiffness matrix and force vector are then transformed to the global ones and assembled. The accuracy and convergence of the folded plate element are assessed using a number of numerical examples. The results show that the element is accurate and converge well to the reference solutions.

A Numerical Investigation on the Structural Behavior of Deficient Steel Frames Strengthened using CFRP Composite

2018-04-10T09:38:43+00:00

Carbon fiber reinforced polymers (CFRP) is one of the materials that is used to strengthen steel structures. Most studies on CFRP strengthening steel on structures have been done on beams and steel columns. No independent study has studied the effect of CFRP strengthening on the structural behavior of steel frames having initial deficiency.The deficiency in steel structures may be created due to the errors caused by construction and others.This study aims to carry out a numerical study on the efficiency of CFRP sheet on strengthening square hollow section (SHS) steel frames having initial deficiency. Seven specimens, five of which were strengthened using CFRP sheets, were analyzed. ANSYS software was used to analyze the SHS steel frames. The results showed that the coverage length, the width, and the number of CFRP layers have a significant effect on increasing and recovering the ultimate load capacity of the SHS steel frames having initial deficiency.

Combining Off-the-Job Productivity Regression Model with EPAâ€™s NONROAD Model in Estimating CO2 Emissions from Bulldozer

2017-10-21T07:51:51+00:00

Heavy duty diesel (HDD) construction equipment which includes bulldozer is important in infrastructure development. This equipment consumes large amount of diesel fuel and emits high level of carbon dioxide (CO2). The total emissions are dependent upon the fuel use, and the fuel use is dependent upon the productivity of the equipment. This paper proposes a methodology and tool for estimating CO₂ emissions from bulldozer based on the productivity rate. The methodology is formulated by using the result of multiple linear regressions (MLR) of CATâ€™s data for obtaining the productivity model and combined with the EPAâ€™s NONROAD model. The emission factors from NONROAD model were used to quantify the CO₂emissions. To display the function of the model, a case study and sensitivity analysis for a bulldozerâ€™s activity is also presented. MLR results indicate that the productivity model generated from CATâ€™s data can be used as the basis for quantifying the total CO₂ emissions for an earthwork activity.

Managerial Skills for Managing Construction Safety

2017-10-21T07:50:14+00:00

Previous 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 manaÂgerial 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.

The Study of Liquefaction Time Stages due to a Short Duration Shaking

2017-10-21T07:54:17+00:00

During the 2006 Yogyakarta earthquake, liquefactions were massively found in Opak River, Yogyakarta, Indonesia. Learning from those events, an experimental study of liquefaction using shaking table was performed, especially to investigate the effect of short shaking duration to liquefaction potential.Â Several experimental tests were performed under varied accelerations (0.3g, 0.35g, and 0.4g) and vibration frequencies (1.4 Hz, 1.6 Hz, and 1.8 Hz), with a short shaking duration of 8 seconds. The liquefaction parameter used in this study was the excess pore water pressure ratio. The results revealed that liquefaction occurs in every loading criteria and the short shaking duration applied on each loading influences time stages of liquefaction, i.e. the liquefaction duration, the initial time of liquefaction, and the initial time of pore water pressure dissipation. In addition, the dynamic loads applied in a short duration influenced the maximum excess pore water pressure ratio.

Effect of the Use of Metakaolin Artificial Lightweight Aggregate on the Properties of Structural Lightweight Concrete

2017-10-21T07:55:54+00:00

This paper investigates the effect of using metakaolin Artificial Lightweight AggreÂgates (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.

Spinning Induced Compression Strength of Precast Hollow Concrete Piles

2017-10-21T08:03:20+00:00

Prefabricated 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.

Compressive Strength of Post Fire Exposed Concrete Column Wrapped with Fiber Reinforced Polymer

2017-10-21T08:09:32+00:00

In 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 720^oC for 180 minutes, the specimens showed concrete andÂ 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 comÂpressive strength was evident despite the low initial strength (<17 MPa). Strength estiÂmation 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 (fâ€™_co) should be adjusted by considering the modulus elasticity and strain limitation to have more precise estimation.

Condition Assessment of the Deteriorated Reinforced Concrete Bridge

2017-10-21T08:06:01+00:00

A comprehensive assessment was conducted to an old reinforced concrete bridge in Brunei Darussalam. This bridge is about 30-40 years old, and has already shown signs of concrete distresses. The main concern was the integrity of the columns, beams and deck, as signs of concrete deteriorations were readily noticeable, e.g. cracks, delaminations, exposed rebar, and concrete spalling. Both visual inspection and non-destructive tests were performed on site. For more detail evaluation, concrete core samples were extracted and sent for testing. Based on information gathered during the investigation and the results of laboratory testing, the reviewed concrete columns were found in bad condition and required immediate repair. The main cause of this concrete distress was the reinforcement corrosion. The vertical column reinforcements were badly corroded and could not function as designed. Without initiating a repair program, it should be prepared for progressive deteriorating conditions, eventually leading to a structural at-risk scenario.

Crack Mapping on Shear-critical Reinforced Concrete Beams using an Open Source Digital Image Correlation Software

2017-10-21T07:57:52+00:00

Three reinforced concrete beams, one with no shear reinforcement and two others with shear reinforcement ratios of 0.4% and 1.1%, were tested to investigate the influence of stirrup spacing on the mode of failure, overall strength and ductility. The results show that the beam reinforced with closely-spaced shear reinforcement failed in a ductile manner, whereas the other two beams with large stirrup spacing and no stirrup exhibited only a small measure of ductility and failed in a brittle manner. The importance of the provisions of maximum spacing is highlighted to ensure adequate anchorage for the stirrups and prevent a premature shear failure to occur. The application of a non-contact monitoring system employing the open source digital image correlation software Ncorr, an ordinary digital camera and a smartphone is demonstrated to provide a visualization of the cracking process throughout the load history.

Study of the Discrete Shear Gap Technique in Timoshenko Beam Elements

2017-08-10T10:50:16+00:00

A major difficulty in formulating a finite element for shear-deformable beams, plates, and shells is the shear locking phenomenon. A recently proposed general technique to overcome this difficulty is the discrete shear gap (DSG) technique. In this study, the DSG technique was applied to the linear, quadratic, and cubic Timoshenko beam elements. With this technique, the displacement-based shear strain field was replaced with a substitute shear strain field obtained from the derivative of the interpolated shear gap. A series of numerical tests were conducted to assess the elements performance. The results showed that the DSG technique works perfectly to eliminate the shear locking. The resulting deflection, rotation, bending moment, and shear force distributions were very accurate and converged optimally to the corresponding analytical solutions. Thus the beam elements with the DSG technique are better alternatives than those with the classical selective-reduced integration.

Barriers to Construction Health and Safety Self-regulation: A Scoping Case of Nigeria

2017-08-10T10:48:42+00:00

This 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 â€˜economic factorsâ€™ mostly explains the barriers to construction H&S self-regulation. This is followed by the â€˜ability to self-regulateâ€™ and â€˜lack of awarenessâ€™. Furthermore, the results show significant differences among small, medium and large construction contractors on seven factors of which include â€˜normative caseâ€™ factors, â€˜H&S is a dutyâ€™, â€˜H&S is the right thingâ€™ and â€˜unfair H&S standards or legislationâ€™. 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.

A Novel Implementation of Nature-inspired Optimization for Civil Engineering: A Comparative Study of Symbiotic Organisms Search

2017-08-10T10:44:39+00:00

The 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

2017-08-10T10:38:45+00:00

This 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.

Modelling the Hydraulic Processes on Constructed Stormwater Wetland

2017-08-10T10:37:09+00:00

Constructed 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.

Early-age Performance of Cement Combination Concrete

2017-08-10T10:34:35+00:00

Heat of hydration up to 72 hours and compressive strength up to 7 days of Portland cement and 17 binary and ternary cements containing fly ash, silica fume, and metakaolin, at a water/cement ratio of 0.50 and addition contents of 20%, 35%, and 55%, were used to examine the early-age performance of concrete. Results revealed that early-age performance depends on the fineness, heat of hydration, and dilution effect of cement combinations. Fly ash, due to dilution effect, reduces the heat of hydration and compressive strength. Using silica fume and metakaolin with increasing content of up to 10% as binary and ternary cement components, due to their fineness and increased heat of hydration, supports the strength development. Most of the cement combinations met the standard of strength requirements for ordinary early-age performance of concrete, while only half of it satisfied the standard for high early-age performance.

Design and Build: Perception of Project Owners and Contractors on Cost in Java, Indonesia

2017-08-10T10:31:21+00:00

Design-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 ownersâ€™ and contractorsâ€™ 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 stakeholdersâ€™ 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.

Bolt Spacing and End Distance of Bolted Connection of Laminated Veneer Lumber (LVL) Sengon

2017-08-10T10:28:04+00:00

This 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 connectionsÂ 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.

Study on Shear Behavior of Concrete-polymer Cement Mortar at Elevated Temperature

2017-10-10T12:22:23+00:00

In this experimental and analytical work, interfacial shear strengths were evaluated at material and member level. Bi-surface shear strength was performed at material level and three-point bending test was conducted at member level. Beams were strengthened by adding steel reinforcement at soffit level and covered by spraying polymer cement mortar (PCM). After curing, strengthened RC beams were exposed to 60 â„ƒ for 24 hours and tested in three point loading test. Flexural capacity, load deflection relationship and failure modes were observed and compared with the strengthened beams tested at 20 â„ƒ. Reduction in flexural capacity was observed with temperature, failure mode was also shifted from flexural mode to debonding mode of failure at elevated temperature. Ultimate shear load and failure modes were predicted by truss analogy approach. Debonding model was proposed by incorporating bi-surface interfacial shear strength, close agreement were observed between experimental and predicted values.

Experimental Investigation on the Effect of Specimen Size in Determining Fracture Parameters of Concrete

2017-10-10T12:22:23+00:00

This paper presents the experimental results in investigating the effect of specimen size (ratio of beam width to aggregate size) on the value of stress intensity factor (KIC) and fracture energy (GF) using three-point bend (TPB). A test method recommended by RILEM was chosen to measure the KIC and the GF as fracture parameters. Three different specimen sizes of concrete beam with water/binder ratio of 0.2 and 0.30 were engaged in the experiments. Both qualitative and quantitative analyses based on the normalized stress against deflection curve, and the KIC and the GF were employed. Statistical analysis was carried out based on coefficient of variation of the measured value of fracture parameters in order to investigate the variability of corresponding results. It was found that specimen size have a relatively insensitive influence on the value of KIC, however, have a significant effect on the value of GF.

Reinforced Concrete Finite Element Modeling based on the Discrete Crack Approach

2017-10-10T12:22:23+00:00

The behavior of reinforced concrete elements is complex due to the nature of the concrete that is weak in tension. Among these complex issues are the initial cracking and crack propagation of concrete, and the bond-slip phenomenon between the concrete and reinforcing steel. Laboratory tested specimens are not only costly, but are limited in number. Therefore a finite element analysis is favored in combination to experimental data. The finite element technique involving the cracks inserting is one of the approaches to study the behavior of reinforced concrete structures through numerical simulation. In finite element modeling, the cracks can be represented by either smeared or discrete crack. The discrete crack method has its potential to include strain discontinuity within the structure. A finite element model (FEM) including the concrete cracking and the bond-slip was developed to simulate the nonlinear response of reinforced concrete structures.

Creep Properties of Walikukun (Schouthenia ovata) Timber Beams

2017-10-10T12:22:23+00:00

This study presents an evaluation of creep constants of Walikukun (Schouthenia
ovata) timber beams when rheological model of four solid elements, which is obtained by
assembling Kelvin and Maxwell bodies in parallel configuration, was adopted. Creep behavior
obtained by this method was further discussed and compared with creep behavior developed
using phenomenological model of the previous study. Creep data of previous study was deformation
measurement of Walikukun beams having cross-section of 15 mm by 20 mm with a clear
span of 550 mm loaded for three weeks period under two different room conditions: with and
without Air Conditioner. Creep behavior given by both four solid elements model and phenomenological
(in this case are power functions) had good agreement during the period of creep
measurement, but they give different prediction of creep factor beyond this period. The power
function of phenomenological model could give a reasonable creep prediction, while for the four
solid elements model a necessary modification is required to adjust its long-term creep behavior.

Comparing Performance of Government and Private Clients in Construction Projects: Contractorsâ€™ Perspective

2017-10-10T12:22:23+00:00

By nature, government and private projects have different characteristics, which influence client performance. This research aims to compare performance of government and private clients in construction projects as perceived by contractors. Six client performance indicators were used, i.e. understanding of project requirements, financial, decision making, management skills, supports for contractor, and clientâ€™s attitude. Data were collected through questionnaire surveys filled in by 117 respondents. The results show that there is a significant difference between both types of client performance. Three variables related to financial indicators, i.e. timely payment, owner value estimate, and payment approval, rank in the bottom three of the government client performance, but in contrast rank in the top three of the private ones. These results suggest that the government clientsâ€™ performance is perceived inferior to the private ones. Establishing a clientsâ€™ forum for sharing knowledge and best practices would be a strategic solution to enhance clientsâ€™ capacities.

Proposed Design Graphs of Geotextile Reinforcement on Soft Clay under Various Field Conditions

2017-10-10T12:22:23+00:00

This paper describes the behavior of reinforced embankments constructed on soft clay subgrade with varying compressible depths, embankment slopes and embankment heights. The stability of the embankment is evaluated using the Bishop method. The resistance moment and the numbers of geotextiles required are examined. It is shown that varying the subgrade and embankment can significantly affect the embankment stability and also the number of reinforcements. It requires a lot of time to design embankment reinforcements, especially when the length of the embankment is tens of kilometers. The main aim of this study is to develop graphs to assist in designing the number of geotextile reinforcements. This paper proposes design graphs to support engineers and designers to determine the required geotextile reinforcements for embankments.

Effect of Temperature on Precipitation Rate of Calcium Carbonate Produced through Microbial Metabolic Process of Bio Materials

2017-10-10T12:22:23+00:00

Concrete is the most widely used construction material in civil engineering. But plain concrete is a brittle material and has little resistance to cracking. The cracking in concrete promotes deterioration such as the corrosion of reinforcing rebar, therefore, repair in filling the crack is often carried out. Recently, repair methods using bio-based materials associated with microbial metabolic processes leading to precipitation of calcium carbonate have been intensively studied. In this study, influencing factors on the precipitation rate depending on the constituents of bio-based material comprising yeast, glucose and calcium acetate mixed in tris buffer solution was examined for improving the rate of initial reactions. In addition, effect of temperature change on the amount of calcium carbonate precipitation was also investigated. The precipitates were identified by X-ray diffraction. It was shown that the increase of temperature lead to a change on calcium carbonate precipitation and caused the pH decrease under 7.0.

Implementation of Decision Support System for Integrated Coastal Zone Management of Sustainable Mariculture Development Industry in Indonesia

2017-10-10T12:22:23+00:00

Indonesia has abundant and potential coastal resources for future development of mariculture industry activities. However, complex problem is found in the land and coastal zone
utilization, among others: coastal environment degradation, resources depletion, conflict and overlapping utilization of marine area. New perspective of Decision Support System (DSS) for
integrated coastal zone management (ICZM) can be used to solve this complexity with respect to the results of high resolution of hydrodynamic and wave numerical model, water quality, and
ICZM. The aim of this paper is to determine the suitable site for the implementation of sustainable future development of mariculture in Galang Island, Riau Province, Indonesia. A
suitability map of geographic information system based on ICZM is indicated by sixteen thematic maps. Implementations of the comprehensive ICZM of DSS criteria prove that Galang
Island has a bright potential of Grouper mariculture development industry by sustainable suitable area of about 12,940 hectares

Managing Pre-Construction and Construction Risks on Project Sites in Abuja-Nigeria

2017-10-17T13:22:50+00:00

Managing risks in construction projects has been acknowledged as a key direction process for the purposes of attaining the project goal in terms of time, cost, quality, safety, and environmental sustainability. Hence, the paper evaluated pre-construction and construction risks on active project sites in Abuja-Nigeria. This was achieved using survey method through the self-administration of 35 questionnaires to the professionals handling the 35 identified projects being undertaking at that time. Results showed that errors and omissions in design and improperly defined project scope had mean score values of 3.03 and 2.54, respectively, were the construction risks most experienced by the professionals during pre-construction. On the other hand, fluctuation in market prices and delays with mean score values of 3.14 and 2.74, respectively, were the construction risks experienced by the professionals during the construction phase of the projects. It is recommended that procurement methods such as construction management should be adopted and stakeholders should keep to their own side of the bargain to avoid unnecessary delays.

The Application of Statistical Design of Experiments to Study the In-Plane Shear Behaviour of Hybrid Composite Sandwich Panel

2017-10-17T13:22:50+00:00

This paper presents a statistical aspect of experimental study on the in-plane shear behaviour of hybrid composite sandwich panel with intermediate layer. The study was aimed at providing information of how significant the contribution of intermediate layer to the in-plane shear behaviour of new developed sandwich panel. The investigation was designed as a single factor experimental design and the results were throughly analysed with statistics software; Minitab 15. The panels were tested by applying a tensile force along the diagonal of the test frame simulating pure shear using a 100 kN MTS servo-hydraulic UTM. The result shows that the incorporation of intermediate layer has sinificantly enhanced the in-plane shear behaviour of hybrid composite sandwich panel. The statistical analysis shows that the value of F0 is much higher than the value of Ftable, which has a meaning that the improvement provided by the incorporation of intermediate layer is statistically significant.

Predicting the Response of Shear-critical Reinforced Concrete Beams using Response-2000 and SNI 2847:2013

2017-10-17T13:22:50+00:00

This study investigates the accuracy of Response-2000 in predicting the response of shear-critical reinforced concrete beams. The experimental data selected was that obtained by Vecchio and Shim in 2004 on twelve reinforced concrete beams which sought to replicate beams originally tested by Bresler and Scordelis in the early 1960s. This study also aims to compare the results obtained to the predictions of SNI 2847:2013. It is demonstrated that Response-2000 is capable of providing accurate predictions of load-deflection responses up to the peak load, but underestimates the ductility of beams that exhibit a mixed flexure-shear failure mode. It is also shown that both methods provide conservative predictions of the shear strength of beams with no shear reinforcement, with the software providing more consistent and reliable predictions of shear strength of beams containing shear reinforcement.