Concrete expands and then contracts because of the increase in temperature during hydration of cement and subsequent fall in temperature. In continuous structures, if this movement is restrained, tensile stresses will develop which can cause cracks to form. Although it is accepted that there will be cracks in reinforced concrete structures, the degree and magnitude of cracking should be controlled. In the design of liquid retaining structures, it is essential to restrict the width of cracks in structures. The maximum design surface crack widths (w) in BS8007 for direct tension and flexure or restrained temperature and moisture effects are as follows: w = 0.2 mm for severe or very severe exposure; and, w = 0.1 mm for critical aesthetic appearance.The design calculations of both the serviceability limit state of cracking due to thermal and moisture effects and flexural can be tedious and time consuming. In the preliminary design stage, the design tables in this document will assist and 'short-cut' the design process and therefore save valuable time. "Design tables to BS8007" has been divided into two parts. Part 1 provides calculations of minimum reinforcement, crack spacing, and crack widths in relation to temperature and moisture effects. It summarises the design formulae and tables A1 to A6 provide calculated reinforcements required for control of thermal and shrinkage cracking. Part 2 provides calculations of crack widths in mature concrete under structural loading. It summarises the design formulae and tables B1 to B36 tabulate the service and ultimate flexural capacity of a range of slab thickness and reinforcement arrangements under differing conditions of crack width limitation, concrete strength and cover.
Descrizione libro Thomas Telford, 1996. Hardcover. Condizione libro: As New. As New. book. Codice libro della libreria F5S3-7-Z-0727725173-5