The Experts below are selected from a list of 14946 Experts worldwide ranked by ideXlab platform
R Park - One of the best experts on this subject based on the ideXlab platform.
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seismic design and construction of Precast Concrete buildings in new zealand
Pci Journal, 2002Co-Authors: R ParkAbstract:Trends and developments in the use of Precast reinforced Concrete in New Zealand for floors, moment resisting frames and structural walls of buildings are described. Currently, almost all floors, most moment resisting frames and many one- to three-story structural walls in buildings are constructed incorporating Precast Concrete elements. Aspects of design and construction, particularly the means of forming connections between Precast Concrete elements, are discussed. The paper emphasizes seismic design since that is where the major difficulties exist in using Precast Concrete in New Zealand. Confidence in the use of Precast Concrete in an active seismic zone has required the use of an appropriate design philosophy and the development of satisfactory methods for connecting the Precast elements together.
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A perspective on the seismic design opf Precast Concrete structures in New Zealand
Pci Journal, 1995Co-Authors: R ParkAbstract:The author describes trends and developments in the use of Precast Concrete in New Zealand for floors, moment resisting frames, and structural walls of buildings. Currently, almost all floors, most moment resisting frames, and many one- to three-story walls in buildings are constructed incorporating Precast Concrete elements. Aspects of design and construction, particularly the means of forming connections between Precast Concrete elements, are discussed. The paper emphasizes seismic design; the aim of the design methods for frames is to emulate monolithic construction. Examples of recent Precast Concrete buildings using the above discussed methods are presented
M. H. El Naggar - One of the best experts on this subject based on the ideXlab platform.
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Circular Precast Concrete manholes: experimental investigation
Canadian Journal of Civil Engineering, 2011Co-Authors: Reem Sabounir. Sabouni, M. H. El NaggarAbstract:Circular Precast Concrete manholes are widely used in sanitary sewer and storm water systems. The lack of detailed technical information on them and the conservatism of their governing codes and standards call for a detailed investigation on them. The main objectives of this paper are to evaluate the state of strains in the Precast Concrete manhole and state of stresses in the soil beneath the base to be used in developing enhanced guidelines for the design of their bases. Three full-scale circular Precast Concrete manholes, two 1200 mm in diameter and one 1500 mm in diameter, were tested in the large-scale geotechnical testing facility (LSGTF) at the University of Western Ontario. Only one 1200 mm manhole base was reinforced. Twenty seven load tests were performed on the manholes, which involved loads representing the Ontario truck loads incorporated in the Canadian Highway Bridge Code. None of the manhole sections tested in the experimental program experienced any cracks. The test results showed that tr...
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Development of a new class of Precast Concrete pipes: a numerical evaluation
Canadian Journal of Civil Engineering, 2007Co-Authors: H. El Naggar, E N Allouche, M. H. El NaggarAbstract:The Precast Concrete pipe industry is in continuous pursuit to add value to its products to strengthen its market competitiveness against other pipe products. The research reported in this paper aimed at developing a new class of Precast Concrete pipes that will provide added value to the final user in comparison with existing products. The technology developed by the authors consists of lenses of a porous material that are used to create "conduits" within the wall of a Precast Concrete pipe, which are continuous across adjacent segments. These conduits can accommodate telecommunication lines (i.e., fibre optics) and other small diameter utilities. The Concrete pipe provides protection for the smaller conduits while conserving underground right-of-way space. This paper describes the results of an extensive numerical study undertaken to evaluate the technical viability of the proposed conduit system. Key words: Precast Concrete pipe, cellular Concrete pipe, finite element analysis, conduit system.
Chih-chen Chang - One of the best experts on this subject based on the ideXlab platform.
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automated dimensional quality assessment of Precast Concrete panels using terrestrial laser scanning
Automation in Construction, 2014Co-Authors: Hoon Sohn, Chih-chen ChangAbstract:Abstract Precast Concrete panels are a popular component for many construction projects in the world. To safeguard the overall quality of these construction projects, it is imperative to ensure that the dimensions and the quality of Precast Concrete panels conform to their design specifications. It is, hence, necessary to develop techniques that can quickly measure the dimensions and reliably assess the quality of Precast Concrete panels. Currently, such measurement tasks mostly rely on trained inspectors, and the process can be rather time consuming. To address these limitations, this study presents a fully automated and non-contact measurement technique that measures and assesses the dimensions and the quality of Precast Concrete panels using a terrestrial laser scanner (TLS). An edge and corner extraction technique is developed to estimate the dimensional properties of Precast Concrete panels from TLS scanning data. To increase the measurement accuracy, a compensation model is employed to account for the dimension losses caused by an intrinsic limitation of TLS. Experimental tests are performed on a laboratory specimen as well as actual Precast Concrete panels to validate the effectiveness of the proposed technique. The results demonstrate that the proposed technique can accurately and reliably measure the length, width and squareness of Precast Concrete panels in an automatic manner.
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Active Dimensional Quality Assessment of Precast Concrete Using 3D Laser Scanning
Computing in Civil Engineering, 2013Co-Authors: Hoon Sohn, Chih-chen ChangAbstract:Quality assessment of Precast Concrete panels is an important factor that affects overall quality of construction. As prefabrication becomes popular at construction sites, demands for automatic and accurate inspections of the dimensions of the Precast Concrete panels have increased. Current techniques for measuring the dimensions of Precast Concrete panels, however, heavily rely on qualified inspectors, and are time and labor demanding. To overcome these limitations, a dimensional measurement technique for Precast Concrete panels is proposed using a 3D laser scanner. For autonomous implementation of the dimensional measurement, a new feature extraction algorithm of extracting only boundary points of the Precast Concrete panels is developed. To increase the measurement accuracy, a compensation model is employed to account for the dimension losses caused by an intrinsic limitation of laser scanners. This study focuses on measurements of length, width and squareness of Precast Concrete panels in a noncontact and speedy manner. Experimental validations on actual Precast slabs are conducted to verify the applicability of the proposed dimensional measurement technique for Precast Concrete panels.
Aleksander Nicał - One of the best experts on this subject based on the ideXlab platform.
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Optimization of reinforcement steel supply to Precast Concrete plants
Arabian Journal of Geosciences, 2019Co-Authors: Aleksander NicałAbstract:In addition to aggregates, cement, and water, reinforcing steel is one of the key building components of Precast products. Steel price fluctuations observed on global markets have a large impact on the cost of production of Precast products made of reinforced and prestressed Concrete. An important issue is, therefore, the proper planning of steel orders and deliveries to the Precast Concrete plants. A significant number of competing warehouses and construction warehouses offer diversified steel prices, which are subject to frequent changes in relatively short periods. This results in a problem in the selection of an appropriate procurement strategy by Precast Concrete plants. An additional unfavorable factor is the ordering of reinforcing steel that is too large in relation to the demands of the Precast Concrete plants, resulting in high costs of its storage in the warehouses or storage yards. In this paper, the issues of optimal planning and delivery of plain, ribbed, and prestressing steel were discussed. For the research and calculation purposes, supplies of steel from four wholesalers to four different Precast Concrete plants were assumed. In addition, the types of steel and the class of bars used to reinforce the elements were discussed. A different level of unit prices for the purchase and delivery of steel in each warehouse and a different demand for each of the four Concrete plants were also assumed. As a result of the analyses carried out, a model was developed, including the strategy of purchasing and supplying plain, ribbed, and prestressing steel with the assumption of minimum costs.
Xinlei Yang - One of the best experts on this subject based on the ideXlab platform.
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SEISMIC TESTS OF Precast Concrete, MOMENT RESISTING FRAMES AND CONNECTIONS
Pci Journal, 2010Co-Authors: Xinlei YangAbstract:This paper presents the results of experimental investigations on four full-scale Precast Concrete connections and a half-scale, two-story, two-bay, Precast Concrete, moment-resisting frame, which consisted of composite Concrete beams and cast-in-place Concrete columns, under cyclic loading. The Precast Concrete connections investigated in this paper included an exterior connection, an interior connection, a T connection, and a knee connection. Test results revealed that the four Precast Concrete connections, as expected, exhibited a strong column-weak beam failure mechanism and failed due to Concrete crushing and fracturing of longitudinal bars as a result of forming a plastic hinge at the fixed end of the beam. The four connections behaved in a ductile manner. However, the displacement ductility of the knee connection was the poorest among them. The Precast Concrete frame exhibited a mixed side-sway mechanism and behaved in a ductile manner. The hysteresis curves of the frame were full and exhibited good energy-dissipation capacity. The global and interstory displacement ductility of the frame was not less than 4.5. In general, the seismic behavior of the Precast Concrete frame was satisfactory. This research could provide structural engineers with useful information about the safety of Precast Concrete-frame structures.
