A House Framing System For Low Cost Construction

Author : Kofi Gyabaa Ayensu
Publisher :
ISBN 13 :
Total Pages : 109 pages
Book Rating : 4.:/5 (173 download)

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Download or read book Model Development for the Evaluation of Cost-effectiveness of Concrete Framing Systems for Low-, Mid- and High-rise Buildings written by Kofi Gyabaa Ayensu and published by . This book was released on 2006 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: The choice of a cost effective lateral-force-resisting system for low-, mid-, and high rise buildings is challenging. There is no streamlined methodology to quantitatively compare the cost-effectiveness of each system beyond the more qualitative perception based evaluation of advantages or disadvantages. Developers currently base their decisions on architectural layout and structural integrity. Cost considerations are often primarily based on experience. This decision making process has three primary shortfalls: (1) it may not incorporate factors which gravely affect the economy of a particular framing system, (2) it may not allow engineers to carry out designs at the least cost and (3) comparison of framing systems may not address the specific building types. At present, there is no documentation for preliminary comparison of lateral-load-resisting framing systems for specific building types which incorporates the above listed shortfalls. As a result, there is a need for an economic model for comparing lateral-force-resisting systems in concrete buildings. This investigation proposes a prototype cost-effective model for selecting either a moment-resisting or shearwall framing system for residential buildings. A model for selecting cost-effective moment-resisting or shearwall framing system will be a valuable tool for all decision makers. Engineers, in particular, will be able to select optimal concrete framing system faster, thus reducing design time and iterations. Furthermore, selection of economic framing system will also result in direct cost savings for concrete buildings project. The study involves the design and cost estimation of eighteen (18) apartment buildings representing moment-resisting and shearwall framing systems. The apartment buildings are modeled with flat plate floor systems having a 25 ft x 25 ft bay size and a floor area of 9,375 ft2 (125 ft x 75 ft). The prototype cost-effective model is calibrated for low-, mid- and high-rise (12-Story) cast-in-place buildings located in low seismic zones or regions with wind speeds of 90 and 150 mph. A review of current design and construction practices forms the framework for the selection of design variables and constants. Designs are carried out according to ACI 318-02 using RISA-3D® (force analysis and column design), pcaColumn (column section investigation) and pcaSlab (flat plate design) software packages. Shearwalls are designed using hand calculation. TimberlineTM version 9.2 is used in the estimation of the construction cost of the framing systems. It uses RSMeans construction cost data for the year 2006. The cost of the framing system represents the construction cost of concrete, reinforcement and formwork in place. The framing systems are compared based on drift requirements and cost. Drift is defined as lateral roof drift for wind force analysis (limit: H/400, where H is story height) and story drift for seismic force analysis (limit: 0.015hsx, where hsx is height below level x). The preferred framing system meets drift requirements and is lower in cost. The results of this pilot study showed that the moment-resisting framing system is the cost-effective choice for: (1) low-rise (3-Story) apartment buildings subjected to wind speeds ranging from 90 mph to 150 mph, and (2) mid-rise (7-Story) apartment buildings subjected to wind speed of 90 mph. The shearwall framings system is the cost-effective choice for: (3) low-rise (3-Story) apartment buildings located in seismic zones, (4) mid-rise (7-Story) apartment buildings located in seismic zones or subjected to wind speeds of 150 mph, and (5) high-rise (12-Story) apartment buildings subjected to wind speeds ranging from 90 mph to 150 mph or located in seismic zones. A prototype cost-effective model is proposed for selecting the cost-effective framing system for low-, mid- and high-rise (12-Story) cast-in-place apartment buildings. In addition, recommendations are developed for future work aimed at producing a comprehensive model for selecting cost-effective lateral-resisting framing system that reflects common scenarios in the building industry.