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Chitosan as a Drinking Water Treatment Coagulant
Issue:
Volume 4, Issue 5, September 2016
Pages:
205-215
Received:
14 July 2016
Published:
15 July 2016
Abstract: Inorganic aluminum or iron salts have been used for many decades to coagulate colloidal particles in surface water prior to flocculation, sedimentation and/or filtration. Although effective, inorganic coagulants have several disadvantages including large chemical dosages required for treating eutrophic waters, large volumes of chemical sludge produced, and toxic effects of metallic coagulants on the aquatic environment. Chitosan is a natural cellulose-like copolymer of glucosamine and N-acetyl-glucosamine. Because of their biodegradability chitosan-based materials have been suggested as a more eco-friendly coagulant for water and wastewater treatment. Chitosan was an effective coagulant in several prior laboratory studies. Practical application of chitosan as a drinking water treatment coagulant is evaluated here through a series of jar tests. The effectiveness of chitosan is compared to aluminum sulphate and ferric chloride with regard to treatment of algal-ladened waters. The optimum chemical dose for coagulation, optimum pH, and effectiveness for algae removal was determined for each coagulant. Practical aspects of applying chitosan at full-scale and the impact of feeding this chemical on overall treated water quality are addressed.
Abstract: Inorganic aluminum or iron salts have been used for many decades to coagulate colloidal particles in surface water prior to flocculation, sedimentation and/or filtration. Although effective, inorganic coagulants have several disadvantages including large chemical dosages required for treating eutrophic waters, large volumes of chemical sludge produ...
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A Fixed Platform Topside Piping System Strength Analysis Under Dynamic Pigging/Slugging Loads
Issue:
Volume 4, Issue 5, September 2016
Pages:
216-224
Received:
18 July 2016
Published:
19 July 2016
Abstract: This paper presents the strength analysis of a fixed platform topside piping system under dynamic pigging/slugging load. Flow assurance analysis by using OLGA provided the flow history in each pipe. Then the dynamic loads at each pipe elbow were added by time sequence onto ANSYS model. The analysis has shown overstressed region under new pigging/slugging loads and proposed modification plan to reduce the stress.
Abstract: This paper presents the strength analysis of a fixed platform topside piping system under dynamic pigging/slugging load. Flow assurance analysis by using OLGA provided the flow history in each pipe. Then the dynamic loads at each pipe elbow were added by time sequence onto ANSYS model. The analysis has shown overstressed region under new pigging/sl...
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Relevance of Contractors’ Prequalification Criteria to Time Performance of Civil Engineering Project
Ologunagba Mulikat Modupe,
Akinmusire Adeleye Ola
Issue:
Volume 4, Issue 5, September 2016
Pages:
225-232
Received:
27 June 2016
Accepted:
11 July 2016
Published:
28 July 2016
Abstract: Civil engineering project completion within predetermined time schedule is usually the desire of the client and every other stakeholder. This has been a mirage because project in this case often fails to meet time target as a result of challenges emanating from its various peculiar characteristics. Civil engineering project completion within estimated time target can be achieved by adopting appropriate contractors’ selection criteria. This research therefore reflected Quantity Surveyors’ and Civil/Structural Engineers’ perception on the relevance of contractors’ prequalification criteria to time performance of civil engineering project. The purpose was to determine the impact of contractors’ selection criteria on time performance of civil engineering project, revealed the contractor prequalification criteria impacting most on time performance of civil engineering project. The primary data used were obtained from construction professionals in consulting, client and contracting organizations engaging in both private and public projects through a well designed questionnaire. Regression analysis and Karl Pearson’s coefficient of correlation were employed to evaluate the impact as well as relationship between contractors’ prequalification criteria and time performance of civil engineering project. Contractors’ prequalification criteria had both positive and negative relationship with time performance of civil engineering project at varying degree of significance. Also, contractors’ prequalification criteria significantly impact on and differently predict time performance of civil engineering project. Therefore, prioritizing reputation and past performance as well as strict adherence to the impact order of the set of criteria for contractors’ prequalification listed in this study would lead to achievement of civil engineering project that meet time target.
Abstract: Civil engineering project completion within predetermined time schedule is usually the desire of the client and every other stakeholder. This has been a mirage because project in this case often fails to meet time target as a result of challenges emanating from its various peculiar characteristics. Civil engineering project completion within estima...
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Dynamic Analysis of High Building with Cracks in Column Subjected to Earthquake Loading
Nguyen Thai Chung,
Hoang Hai,
Shin Sang Hee
Issue:
Volume 4, Issue 5, September 2016
Pages:
233-240
Received:
25 June 2016
Accepted:
11 July 2016
Published:
2 August 2016
Abstract: This paper is devoted to studying the dynamic response of a high building on an elastic foundation with cracks on the column of the building under earthquake loading using the finite element method (FEM). The authors used a 3D modeling frame - plate system and integration method developed by Newmark, along with construction calculation programs in the Matlab environment to analyze the problem. The results were reflected the effect of the cracks on the columns and other parameters.
Abstract: This paper is devoted to studying the dynamic response of a high building on an elastic foundation with cracks on the column of the building under earthquake loading using the finite element method (FEM). The authors used a 3D modeling frame - plate system and integration method developed by Newmark, along with construction calculation programs in ...
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Improvement of Sub Base Soil Using Sand-Cement Stabilization
Md. Mahmud Hasan Mamun,
Md. Firoz Mahmood Ovi,
Farhana Akhter,
Saurav Barua,
Mohiuddin Ahmed,
Thahomina Jahan Nipa
Issue:
Volume 4, Issue 5, September 2016
Pages:
241-246
Received:
22 June 2016
Accepted:
15 July 2016
Published:
3 August 2016
Abstract: Sand is the most available construction material in Bangladesh. Sand- cement stabilization is more cost effective and environment friendly for the construction of sub-base pavement layer in perspective of Bangladesh. The researchers conducted an investigation for the use of cement stabilized fine to medium sand in the construction of roads. Sands from various location such as—Mymensingh, Fajilpur Munshigonj and Sunamgonj are procured for this research work. Although Sunamgonj and Fajilpur sand are slightly expansive, those sand can be easily used as a substitute of unbounded material. According to the laboratory tests, all of the four types of sand have satisfied the criteria of sub-base layer strength on 14 days. The sand-cement material with 8 to 10% cement proved to be adequate for sub-base layers of heavily trafficked roads. It is observed that, sand sample with 8% cement mixes obtained from Fajilpur and Sunamgonj fulfill the specification requirements of sub-base layer for low traffic roads. On the basis of quantitative evaluation, appropriate sand-cement stabilization systems for roads need to be exercised and suggested.
Abstract: Sand is the most available construction material in Bangladesh. Sand- cement stabilization is more cost effective and environment friendly for the construction of sub-base pavement layer in perspective of Bangladesh. The researchers conducted an investigation for the use of cement stabilized fine to medium sand in the construction of roads. Sands f...
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Parametric Study of the Lateral Behavior of Cast in Drilled Hole Piles
Samir Abdul Baki Jabbar Al-Jassim,
Rafi Mohammed Qasim
Issue:
Volume 4, Issue 5, September 2016
Pages:
247-253
Received:
8 July 2016
Accepted:
18 July 2016
Published:
15 August 2016
Abstract: A cast in drilled hole (CIDH) piles are to be used as a bridge foundation. The geotechnical data of the site indicate that the soil profile consist of 10m normally consolidated soft clay underlined by a thick layer of over consolidated stiff clay. Three different pile diameters of 1.6m, 1.8m and 2m are selected from the analysis to be used for a depth of 30m below ground level and an average height of 5m above ground level. To investigate behavior of these (CIDH) piles under lateral loads, an analytical parametric study is performed to evaluate the ultimate lateral load capacity of the piles (which is assumed to cause a pile head displacement of 10% of the pile diameter) and the distribution of shear force and bending moment along the depth of the piles. The soil is represented by two ways, linear and nonlinear material. For the linear case, a linear brick finite element is used to represent the soil with either a linearly variable modulus of elasticity from ground level to the bottom of the pile or a constant modulus of elasticity for the top 10 meters (the soft clay) while linearly varying for the next 20m. For the nonlinear case, the P-Y curves method is used to represent the soil by nonlinear springs at intervals of 1 meter. In both cases (linear and nonlinear soil), the piles are assumed to behave linearly. Results obtained indicate that the ultimate lateral load capacity of the piles from the nonlinear case is in the range of 50% to 60% of the linear case.
Abstract: A cast in drilled hole (CIDH) piles are to be used as a bridge foundation. The geotechnical data of the site indicate that the soil profile consist of 10m normally consolidated soft clay underlined by a thick layer of over consolidated stiff clay. Three different pile diameters of 1.6m, 1.8m and 2m are selected from the analysis to be used for a de...
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Occupational Accident Patterns and Prevention Measures in Construction Sites in Nairobi County Kenya
Raymond Kemei,
Julius Nyerere
Issue:
Volume 4, Issue 5, September 2016
Pages:
254-263
Received:
31 July 2016
Accepted:
11 August 2016
Published:
29 August 2016
Abstract: Construction accidents don’t just happen, they are initiated by unsafe acts, unsafe conditions or both. The construction industry in Kenya plays a vital role in achieving social and economic development goals, providing shelter, infrastructure, and employment. A study was carried out to identify the common accidents in construction sites and to examine the characteristics of the injured and deceased workers and evaluate factors that cause these accidents in Nairobi County, Kenya. The study cross examined data from Directorate of Occupational Safety and Health (DOSH) from Nairobi County ranging from 2010-2014. The study also utilized on-site questionnaires that were administered to 60 contractors in 9 administrative regions in Nairobi County. They constituted all class NCA2 contractors in the county as well as a few NCA3 and NCA4 contractors. Some 41 questionnaires were returned. Accidents were classified by the age of workers, time and month of the accident, location of an accident, causes of accident and management factors affecting the accident. The study established that 65% of all reported accidents occurred to workers below 37 years old. The accidents peaked between tea break (10am), lunch break (1pm) and after lunch (3pm) and during the months of June and July. The study determined that most construction site injuries were as a result of workers falling from heights (37%), being hit by falling objects (28%) and accidents occurring as a result of workers operating equipment (20%). Relative Importance (R. I) index of construction hazards were calculated for 24 factors contributing to construction site accidents. The top five hazards identified were: (1) reluctance to provide resources for safety (0.820); (2) lack of staff training (0.814); (3) lack of a safety policy and enforcement of safety regulations (0.795); (4) poor safety consciousness among workers (0.766); and (5) lack of strict operational procedures (0.756) in construction sites. The study concluded that in order to improve safety in the construction industry, each company should have a health and safety policy which is to be implemented in each contract. Furthermore, construction companies need to provide workers with the necessary Personal Protective Equipment (PPE), such as safety belts, retaining belts, safety ropes, and safety harness, and catch nets to prevent workers from being hit by falling materials and to secure them against falling from heights.
Abstract: Construction accidents don’t just happen, they are initiated by unsafe acts, unsafe conditions or both. The construction industry in Kenya plays a vital role in achieving social and economic development goals, providing shelter, infrastructure, and employment. A study was carried out to identify the common accidents in construction sites and to exa...
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