336 CHAPTER 10 Materials
normally cylindrical and are limited in length to eliminate the possibility of failure being caused by
instability.Again,contractionsaremeasuredoveragivengaugelengthbyasuitablestrainmeasuring
device.
Variations in test pieces occur when only the ultimate strength of the material in compression is
required.Forthispurpose,concretetestpiecesmaytaketheformofcubeshavingedgesapproximately
10cmlong,whilemildsteeltestpiecesarestillcylindricalinsectionbutareoftheorderof1cmlong.
Bending Tests
Many structural members are subjected primarily to bending moments. Bending tests are therefore
carriedoutonsimplebeamsconstructedfromthedifferentmaterialstodeterminetheirbehaviorunder
thistypeofload.
Two forms of loading are used, the choice depending on the type specified in Codes of
Practicefortheparticularmaterial.Inthefirst,asimplysupportedbeamissubjectedtoa“two-point”
loading system, as shown in Fig. 10.3(a). Two concentrated loads are applied symmetrically to the
Fig.10.3
Bending test on a beam, “two-point” load.