The Behaviour and Design of Cold-Formed Channel and Z-Section Beams
Abstract
The purpose of this investigation is to provide experimental data on the strength of cold-formed lipped channel and Z-beams to verify theoretical predictions, and to develop recommendations for the design strengths of such beams.
The design buckling strengths of cold-formed beams are currently calculated using theory and experimental data for hot-rolled I-section beams. Other loading conditions such as combined bending and torsion of channels or biaxial bending of Z-beams have few design guidelines, and those available are largely based on methods of designing hot-rolled I-section columns. The design code formulations based on those for hot-rolled I-sections may be inappropriate for cold-formed sections because of the different behaviour and properties of cold-formed beams. To satisfy the need for test data on cold-formed unbraced beams, an experimental program was established to measure the strengths of cold-formed channels and Z-beams and to gather a series of subsidiary test data.
Lateral buckling tests were conducted on simply supported unbraced cold-formed lipped channel beams of two different cross-sections, and tests on lipped Z-beams made from one type of cross-section. The beams were loaded with central concentrated loads at different heights with respect to the shear centre. The test results are compared with the theoretical predictions and capacities calculated using existing Australian design codes AS 4100 and AS/NZS 4600. Improvements are suggested for future design code formulations for the lateral buckling capacities of cold-formed channel and Z-beams.
Bending and torsion tests were conducted on simply supported channel beams of two different cross-sections loaded eccentrically at midspan while biaxial bending tests on Z-beams made from one type of cross-section. The concentrated loads were applied with different eccentricities for the channel beams, and with different angles of inclination for the Z-beams. The results from both series of tests are compared with the analytical predictions and used to develop simple interaction equations that can be used in the design of eccentrically loaded channels and Z-beams under inclined loading
No comments:
Post a Comment