Formwork Design Tables课件.pptVIP

Temporary Structures CM 420 Formwork Design Tables Lecture 6 Formwork Design Tables Based on the principles outlined so far, safe spans for many timber and plywood formwork components have been calculated and arranged in tables for use by formwork designer. The tables cover single span beams, two-span beams, and beams continuous over three or more spans carrying a uniform distributed load. The tables can be used to develop a preliminary design for cases where rigorous structural analysis is required for formwork design. Formwork Design Tables Four sets of allowable (adjusted) stresses are included in the tables. Adjusted stresses for long term and short term loading stresses for formwork made of No. 2 grade Southern Pine and Douglas Fir-Larch. Adjusted stresses for both short term and long term loading of No. 2 Spruce-Pine-Fir and No. 2 Hem-Fir. Table 7-1 shows the expressions which are used to calculate the safe support spacings (spans). Formwork Design Tables Table 7-1: Expressions Used in Calculating the Safe Support Spacings of Chapter 7 Design Tables Formwork Design Tables The tables are in four groups: Table 7-2 through 7-4 for plywood sheathing Tables 7-5 through 7-7 for joists, studs, stringers or any other beam components of the formwork where framing members are used singly Tables 7-8 through 7-10 for wales or other formwork components where the members are used double Table 7-11 and 7-12 for shore loading and bearing checks Formwork Design Tables Nominal lumber sizes are shown in the tables. All calculations are based on lumber finished on all four surfaces (S4S). Actual thicknesses are shown for plywood. In each table, it is shown whether the safe span is controlled by bending, deflection of shear. Formwork Design Tables Sheathing Design: Tables 7-2—7-4 Tables 7-2, 7-3, and 7-4 were calculated for both long term and short term loading using the information from Table 4-2, for face grain parallel and perpendicular to direction of the span. Tables 7-