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Terminology of loads explained

Terminology of loads explainedThe terminology and notation currently used in CFA Guidance Note: Procedure for site testing construction fixings and in particular for determining Allowable Loads, has been changed to bring it into line with BS 8539. 

 

 

The key difference is that the word Load is used only as a general term. The term Action is used for loads applied by the fixture, and Resistance for the capability of the anchor to withstand the action.

A more detailed guide to terminology and notation used in anchoring is to be found in a Guidance Note: Anchor terminology and notation

Note: In the table below under the heading "Old terminolgy' some symbols do not appear as intended. The symbol Y, describing factors for test loads. is intended to be gamma while the new equivalent shown as v is intended to be nu. See BS 8539 section 3.2 symbols or the CFA Guidance Note: Anchor terminology and notation for the correct representation.

 

 

 

Old terminology

New terminology

Meaning/comment

Preliminary test

Test for allowable resistance (simplified approach)

New title describes more accurately what the test achieves and differentiates it from the other method of achieving the same objective.

Ultimate load test

Test for allowable resistance (statistical approach)

New title describes more accurately what the test achieves and differentiates it from the other method of achieving the same objective.

Applied load, Napp

Characteristic action, NSk

The actual load intended, by the designer, to be applied to the fixing (Sometimes referred to as unfactored load, in CFA Guidance Note for Scaffold Anchors as "Working Load".)

Recommended Load, Nrec

Recommended resistance, Nrec

Load which may be applied to the fixing in the bas material specified. Safe working load (SWL) as quoted by the manufacturer.

Allowable Load, Nall

(Admissible load in previous Guidance Note)

Allowable resistance, NR,all

SWL of the fixing into the base material concerned as determined from site tests - usually only required when no manufacturer's Recommended Load is available.

Test load, Ntest

Test load, Ntest

Load to be applied in tests for allowable loads, Ntest = NSk x νtest

Proof load, Np

Proof load, Np

Load to be applied during Proof Tests, Np = NSk x νP,test

Ultimate load, Nu

Ultimate load, NRu

Maximum or failure load recorded in a single test

Mean Ultimate load, Num

Mean Ultimate load, NRu,m

Mean ultimate load recorded in a series of tests

Nu,ave

Nu,ave

Average load recorded in tests for allowable load

Nu,low

Nu,low

Lowest load recorded in tests for allowable load

γtest

νtest

factor used to determine the test load,

 

νP,test

factor used to determine the proof test load

γave

νave

factor used to determine allowable resistance from Nu,ave

NR,all = Nu,ave ÷ νave

γlow

νlow

factor used to determine allowable resistance from Nu,low

NR,all = Nu,ave ÷ νave

In the above definitions "N" implies Tensile loads. For shear loads "V" is used.