ISO/TR 4553:2022 保守性限界状態での建物および建物要素の変形と変位 | ページ 2

Foreword

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This document was prepared by Technical Committee ISO/TC 98, Bases for design of structures, Subcommittee SC 2, Reliability of structures.

Introduction

The underlying aim of this document is to provide guidance for the structural designer to identify those aspects of deformation that affect the suitability of a building for the purposes for which it was intended, and to suggest certain criteria by which the serviceability of the building in this respect can be assessed. In addition, numerical values for these criteria are provided to give some guidance where this might be appropriate.

Deformations of building structures can affect the serviceability of the building by causing damage to parts of the building and its finishes, by disturbing or harming users, or by preventing proper use of the building. Deformations can be caused by ground movements, by differential settlement of foundations, by environmental and occupational loads, by pre-stressing forces, and by movements of building materials due to creep under load, or changes in temperature, moisture content or chemical composition.

Prior to the 1960s, the allowable design stresses assigned to most engineering materials were low and design methods were conservative. This resulted in highly redundant building forms, typically with comparatively short spans and relatively massive elements. Such buildings were generally very stiff to the extent that deflection problems were uncommon. There was little need to realistically ascertain the actual deformation of elements since these seldom controlled design or element sizes.

In contrast, modern design methods result in structures that are generally lighter, possess less redundancy and are much more reactive to imposed loads. Modern structural design and material standards aim to realistically reflect the actual material properties and provide innovative designers with the tools to utilize the full potential of new materials. Material technology has also advanced, with higher strength materials allowing longer spanning elements, which are typically more susceptible to deformations and vibrations. Designers need to assess the response of each element to the appropriate combination of realistic actions, often modelling these using analytical and computer techniques. The engineering rationale inherent within such an approach is complex. Several assumptions are required to assess that response, both to reflect the actual condition of the element in service and to ascertain the response of that element to the applied action.

This document identifies and discusses many of the assumptions that are made when assessing elemental deformation control. This document provides more detailed background information to assist in assuring that these assumptions are appropriate and it provides guidance which allow the sensitivity of such assumptions to be assessed with regard to the member, its physical properties or its in-service condition.

1 Scope

This document establishes the basic principles for the determination of deformations of buildings at the serviceability limit state when formulating national standards and recommendations. This document contains information on how serviceability for buildings and building elements is dealt with in some national standards.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 8930:2021 apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

Bibliography