Concrete Formwork Svstems - Part 3

Slab Form Design - Các hình thức bê tông được thiết kế cấu trúc được yêu cầu để hỗ trợ tải bao gồm bê tông tươi, vật liệu xây dựng, thiết bị, công nhân, tác động của các loại, và đôi khi gió. Các hình thức phải hỗ trợ tất cả các tải áp dụng mà không sụp đổ hoặc lệch quá nhiều. Báo cáo Ủy ban ACI 347-1994 xác định những người tải ứng dụng và cung cấp cho một số hướng dẫn về an toàn và bảo trì. Trên cơ sở các nguyên tắc này, một số các. | 3 Slab Form Design Properties of Form Materials Properties of Area Properties of Sawn Lumber Properties of Plywood Slab Form Design Design Steps Copyright Marcel Dekker Inc. All rights reserved. Concrete forms are engineered structures that are required to support loads composed of fresh concrete construction materials equipment workers impact of various kinds and sometimes wind. The forms must support all the applied loads without collapse or excessive deflection. ACI Committee Report 347-1994 defines those applied loads and gives a number of guidelines for safety and serviceability. Based on these guidelines a number of design tables have been developed for the design of concrete formwork. These tables are useful design tools. However they do not take into consideration stress modification factors that are provided by the National Design Specification for Wood Construction NDS 1991. This chapter presents a design procedure for all-wood concrete slab forms based on NDS 1991 and Plywood Design Specification 1997. The objective of the formwork design is to determine the safe spacing for each slab form component sheathing joists stringers and shores and ensure that each component has adequate strength to resist the applied pressure without exceeding predetermined allowable deflection. PROPERTIES OF FORM MATERIALS The following sections provide an overview of some important properties of structural sections that are used in formwork design. Readers familiar with these expressions should start with Section . Copyright Marcel Dekker Inc. All rights reserved. PROPERTIES OF AREA Certain mathematical expressions of the properties of sections are used in design calculations for various design shapes and loading conditions. These properties include the moment of inertia cross sectional area neutral axis section modulus and radius of gyration of the design shape in question. These properties are described below. 1. Moment of inertia. The .