Chapter 8 Pre-Engineered Structures: Buildings, K-Spans, Towers, and Antennas

CHAPTER 8 PRE-ENGINEERED STRUCTURES: BUILDINGS, K-SPANS, TOWERS, AND ANTENNAS As a Steelworker, pre-engineered metal structures are a special interest to you; you are expected to assemble and disassemble them. Rigid-frame buildings, k-spans, steel towers, and antennas are some of the more commonly used structures, particularly at advanced bases overseas. All pre-engineered structures, discussed in this text, are commercially designed structures, fabricated by civilian industry to conform to the specifications of the armed forces. The advantage of pre-engineered structures is that they are factory-built and designed to be erected in the shortest possible time. Each pre-engineered structure is shipped as a complete building kit including all the necessary materials and instructions to erect it. Various types of pre-engineered structures are available from numerous manufacturers, such as Strand Corporation, Pasco, and Butler; however, all are similar because each is built to military specifications. It would not be practical to try and include all of the structures that each company fabricates; therefore, in this manual a description of the basic procedures for erecting and dismantling the 40-foot by 100-foot building is provided as an example. PRE-ENGINEERED BUILDINGS This chapter introduces you to the design, the structure, and the procedures for the erection of the typical pre-engineered buildings (P.E.B.), the K-spans, the pre-engineered towers, and the antennas. The basic pre-engineered metal building (fig. 8- 1) is 40 feet wide by 100 feet long. Although the unit length of the building is 100 feet, the length can be increased or decreased in multiples of 20 feet, which are called “20-foot bays.” The true building length will be equal to the number of 20-foot bays plus 6 inches; each end bay is 20 feet 3 inches. The building is 14 feet high at the cave and 20 feet 8 inches at the ridge. Pre-engineered buildings are ideal for use as repair shops or warehouses because they have a large, clear floor area without columns or other obstructions as well as straight sidewalls. This design allows floor-to-ceiling storage of material and wall-to-wall placement of machinery. The column-free interior also permits efficient shop layout and unhindered production flow. After a building is up, it can be enlarged while in use by "bays”, providing additional space under one roof. If desired, buildings can be erected side by side “in multiples.” When a building is no longer needed it can be disassembled, stored, or moved to another location and re-erected because only bolted connections are used. There is no field riveting or welding. The rigid frame is strong. It is designed for Figure 8-l.—Completed 40-foot by 100-foot by 14-foot pre-engineered building. 8-1