Page 71 - Unit2.docx

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Figure 9-2 test being carried out

Limit State Design

Introduction

Traditionally, design resistance of foundations has been evaluated on an
allowable stress basis that piles were designed with ultimate axial capacity
between 2 and 3 times than working load. However structural design is now
using a limit state design (LSD) bases whereby partial factors are applied to
various elements of the design according to the reliability with which the
parameters are known or can be calculated. LSD approach is the base of all the
Eurocodes, including that for foundations design. It is believed that Limit state
design has many benefits for the economic design of piling. The eurocode
approach is particularly rigorous, and this guide adopts the partial factors
presented in the codes.

Eurocode 7 divides investigation, design and implementation of
geoconstructions into three categories. It is a requirement of the code that project
must be supervised at all stages by personnel with geotechnical knowledge.

In order to establish minimum requirements for the extent and quality of
geotechnical investigation, deign and construction three geotechnical
categories defined. These are: Geotechnical Category 2, 2, 3.

20.2 Goetechnical category 2, GC 2

this category includes small and relative simple structures:

-for which is impossible to ensure that the fundamental requirements will be
satisfied on the basis of experience and qualitative geotecnical investigation;

-with negligible risk for property and life.

Geotechnical Category 2 procedures will be only be sufficient in ground conditions
which are known from comparable experience to be sufficiently straight-forward