Applied Mechanics and Materials Vol. 735

Abstract: Construction industry is one of the most profitable sectors in Iran’s economic. Delay is common problem in the construction projects in Iran. By considering all viewpoints of the parties, this research identified the most effective and severe causes of delay in construction projects in the Capital of Iran, Tehran. Questionnaires were distributed among respondents who are involved in the construction project in Tehran. The process of data analysis and discussions were conducted based on the two statistical techniques namely descriptive analysis (RII) and factor analysis. Using factor analysis, most critical factors of Tehran’s construction delay were recognized as: (1) lack of commitment; (2) inefficient site management; (3) poor site coordination; (4) Complexity in heritage and legislation; (5) Lack of estimation skills and skilled workers; (6) Lack of communication between parties; (7) Improper planning; and (8) Lack of clarity in contract. These results are anticipated to be important contributions to construction projects in Tehran in controlling the time overruns in construction contracts.

Abstract: In recent decades Performance Based Seismic Design (PBSD) is widely used for evaluation of the structural performance because of its capability and simplicity to estimate inelastic response of structure. On the other hand, some times in construction based on architectural decision, size of beams are being decreased. The aim of this attempt is to investigate the effect of beam size on structural behavior based on PBSD method using simple procedure. Capacity Spectrum Method (CSM) was implemented using set of RC frames (2, 4, 6, 8 and 10 story with three bays) and ETABS2000 to determine the weakness of the frames system due to their reduced beam size. The performance of the frames was measured at Life Safety damage control level.

Abstract: This paper reports preliminary findings on the properties of concrete produced using iron ore tailings obtained from ZCM Minerals SDN BHD located in Kotta Tingi, Johor, Malaysia. The Iron Ore Tailings (IOT’s) a waste product, with particle size range from (850μm - 75μm) obtained from Iron Ore Processing was utilized as fine aggregate to produce concrete. Based on British Standard (BS) guidelines, normal concrete mix was designed. Five types of concrete samples (C0, C1, C2, C3, and C4) were produced, with the percentage of tailings used to replace sand as fine aggregate ranging from 0 to 40[%]. The reference sample is C0 with no tailings and the four others, containing tailings at 10[%] intervals. The effect of iron ore tailings on the consistency of the fresh concrete were studied, as well as the density, compressive strength, flexural strength and splitting tensile strength, of the hardened concrete. The results of the consistency tests on concrete shows that the slump values ranges from 81 to 53[mm] from concrete sample C0 to C4 respectively, while the compacting factor values ranges from 0.92 to 0.89 respectively. The density of the produced concrete cube samples falls within the range 2350 to 2430[kg/m³]. The concrete sample C3 gave the highest compressive strength value of 43.70[N/mm²]. The concrete sample C3 also gave the highest flexural strength value of 4.79[N/mm²], while the The concrete sample C4 gave the highest splitting tensile strength value of 4.0[N/mm²] after curing period of 28[days].

Abstract: The use of structural timber has never caught on in Malaysia despite the fact that the country is a major exporter of many commercially important hardwoods such as dark red meranti, kapur and keruing, among others. Chief concern among structural designers is the fact that due to its brittle tensile behaviour, timber tends to fail abruptly under the application of flexural loads. The presence of localized defects such as knots also tend to aggravate the problem as these localities are obviously not only weaker compared with the overall strength of the timber member considered, but also tend to be stress concentration regions. For engineered wood products (EWPs) such as glued laminated timber, the introduction of finger joints further compounds the predicament of the structural engineer as these joints are now crack initiation locations because these joints tend to open up when experiencing tensile forces due to flexural loads. However, it is possible to address these concerns by carrying out flexural strengthening of timber members using materials as varied as steel, fibre reinforced polymers (FRPs), biological fibres, and perhaps timber itself, albeit of a higher strength. This paper seeks to review the current strategies undertaken by international researchers to fortify and bolster the flexural strength of timber in order to make it an attractive construction material to architects, engineers and builders alike.

Abstract: The main objective of this study was to obtain the correlation between the severity of damage to the stiffness of the frame in the format of its intrinsic dynamic properties, the natural frequency of the structural system at damaged and undamaged state. In this research, a laboratory test was performed on the precast post-tension frame of a similar dimension and strength specification to Jabatan Kerja Raya (JKR) school buildings. The modal frame is a reduced in scale of 1 to 5 and subjected to cyclic lateral loadings and monitored its frequency through vibration test. The vibration test was performed at each end of the cycle of a lateral pushover test. The vibration data was recorded by accelerometers due to external forced vibration to assess its natural frequency, mode shapes and damping values of the system. This research found that there is a physical tangible relationship between natural frequency changes and stiffness in the frame. The results showed that as the severity of damage increases, the natural frequency of the frame decreases significantly, indicating that softening of the system that lead to a favorable ductility for earthquakes.

Abstract: Metakaolin is a produce from Kaolinite. Meanwhile, Kaolinite is a natural clay mineral that consists of so many mineral materials, metakaolin inclusive, that can be used in many areas of life and hence sustainable in contents if process adequately. The issue of global warming coupled with a general belief of greenhouse gas emission through the production and usage of cement, a main building and infrastructures construction materials, necessitate for the substitution of cement in building materials most especially concrete. This study focused on the effect of metakaolin on the early day's strength of sandwich engineered cementitious concrete modified with nanosilica particles. The nanosilica in this mix served two purposes, one as a cementitious substitute and secondly as to increase the silica content of the normal sand used. The fresh and engineering properties of samples with 12% weight replacement of ordinary Portland cement with metakaolin was also evaluated. The surface area of metakaolin used in this experiment was 25.4m²/g. The result shows that the sandwich ECC samples modified with nanosilica produced higher strength compared with the base standard M45 ECC.

Abstract: Vibration is a serious concern for tall structures during a natural disaster such as earthquake, wind storms, sea waves and hurricanes. The risk of occurrence of structural damage can be decreased by using a controlled vibration system to increase the damping characteristics of a structure. Damping is defined as the ability of the structure to dissipate a portion of the energy released during a dynamic loading event. The aims of this study are (1) to investigate a 4-storey 2D steel frame retrofit with viscous damper to reduce its vibration and (2) to demonstrate the performance of such a damper when fitted to a structure by analysis and tests the model. Therefore, a series of shaking table tests of the 4-storey 2D steel frame with and without viscous damper (VD) was carried out to evaluate the performance of the structure. The results of the experimental tests illustrate that viscous dampers decrease the structural responses of slender frame without changing their behavior on the shaking table. In other words, the displacement of the structure is reduced, however, there is no any transition of flexible to stiff structure related to its dynamic responses.

Abstract: Contractors are one of the important parties in completing a construction project as they directly involved in the construction works execution. Therefore, contractors’ performance should be monitored and assessed on a regular basis to ensure the success of the project, particularly by identifying the failures and shortfalls, as well as any delays and losses that might occur due to the poor productivity of the contractors. A systematic performance appraisal is one of the endeavours in ensuring that the contractors’ performance is as per the expectation of the stakeholders, particularly the client. Hence, this paper provides a review on the contractors’ performance appraisal practices in construction industry in Malaysia. Questionnaire survey on 214 respondents from construction industries, ranging from contractors to project managers, was undertaken where the results showed that contractors’ performance appraisal in a particular construction project is very essential as it drives the project towards better improvement and ultimate success.

Abstract: Density currents are flows driven by density differences caused by suspended fine solid material, dissolved contents, temperature gradient or a combination of them. Reservoir sedimentation is often related to sediment transport by density currents. This sedimentation can block bottom outlets, reduce the capacity of reservoir and harms the dam power plants. The head is the leading edge of density currents. In this paper, the influences of artificially roughened beds on dynamics of the frontal region of density currents are investigated experimentally. Three rough beds using conic roughness elements and a smooth bed were tested. The observed trend is that as the surface roughness increases the head concentration and velocity decreases.

Abstract: Consequence assessment is an integral part of risk assessment process. There are many types of consequences loss due to pipeline failure such as assets loss, environmental loss, production loss and human health and safety (HSE) loss. Yet, some of these factors are often neglected in environmental loss assessment such as agricultural, demographic, industrial and local factors. In real life problem solving, the factors of environmental consequence are not assessed precisely due to unquantifiable, deficient and lack of knowledge on the real on-site parameters. These limitations lead to the use of fuzzy-based approaches in environmental consequence assessment using on-site parameters as the main focused on this paper. Even though the basic model can be comparable to other established model, a lot of customization needs to be carried out network-wise, based on the carried products by the pipeline, locally applicable regulations and geographical surroundings. Knowledge of local conditions, past history and experience of similar incidents, are required to be considered and incorporated to provide a realistic picture of environmental consequence model. The damage area of the incident is calculated using ALOHA software by considering the details of the site such as atmospheric and topography condition. Finally, the proposed methodology is applied to a case study on high consequences areas of buried gas pipeline site in Malaysia to generate the environmental consequences index represented in each selected sites. The result can be utilized to determine the overall consequences loss using appropriate simulation analysis.