Abstract
Steel trusses are the most popular system for supporting long-span roofs in commercial buildings, such as warehouses and aircraft hangars. There are several advantages of steel trusses, such as lightweight, ease of handling and erection, and geometric flexibility. However, they have some drawbacks, such as high material and maintenance cost, and low fire resistance. In this paper, a precast concrete truss is proposed as an alternative to steel trusses for spans up to 48 m (160 ft) without intermediate supports. The proposed design is easy to produce and has lower construction and maintenance costs than steel trusses. The truss consists of two segments that are formed using standard bridge girder forms with block-outs in the web which result in having diagonals and vertical members and reduces girder weight. The two segments are then connected using a wet joint and post-tensioned longitudinally to form a crowned truss. The proposed design optimizes the truss-girder member locations, cross-sections, and material use. A 9 m (30 ft) long truss specimen is constructed using self-consolidated concrete to investigate the constructability and structural capacity of the proposed design. A finite element analysis of the specimen is conducted to investigate stresses at truss diagonals, verticals, and connections. Testing results indicate the production and structural efficiency of the developed system.
Highlights
Structural steel is typically and widely used for long-span roof applications, such as warehouses, storage facilities, and airplanes hangars
Using structural steel has been the only option when it comes to long-span roofs due to ease of handling and erection, geometric flexibility, and lightweight
Despite the advantages of structural steel roof systems, they have the following disadvantages: low fire resistance, being prone to corrosion, high maintenance cost, long lag period in steel orders, and increasing prices of steel. Most of these disadvantages can be addressed by using precast concrete components as they have excellent fire and corrosion resistance, low production and maintenance cost, and short order period
Summary
Structural steel is typically and widely used for long-span roof applications, such as warehouses, storage facilities, and airplanes hangars. According to e.Construct USA, LLC, the use of precast concrete truss system, along with Z-shape steel purlins and metal roof decking resulted in about 25% saving in the building cost compared to the original design using structural steel. This is a significant saving that motivated the authors to further investigate precast concrete truss systems to optimize their designs, improve their constructability, and accommodate production practices in the United States. Several enhancements, which will be discussed, have resulted in cost and weight reductions, and, the potential of using precast concrete trusses in long-span roof applications
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