A Numerical Study on Shear Buckling Capacity of Z-Section Steel Purlin with Opening

Cold-formed Z-section steel purlin is one of the most commonly available steel purlin worldwide. A numerical study on Z-section steel purlin with opening under shear loading was carried out. Six (6) variables such as opening size, opening shape, section type, opening distance, opening position and opening arrangement were identified and tested to investigate their effect on shear capacity of Z-section steel purlin. Results indicated that the presence of web opening did not improve the shear behaviour of Z-section steel purlin. However, non-negligible improvement in terms of volume reduction was observed. Each 0.1D (where D is the section height) enlargement of opening size caused an approximate 10% drop in shear buckling capacity (SBC) while volume reduction (VR) increased exponentially. Diamond shape performed up to 55% better in SBC compared to circular shape opening but circular shape opening performed up to 24% better in VR. Sections with smaller section height had higher SBC compared to sections with bigger section height. Nevertheless, sections with bigger section height had higher VR. No significant difference in terms of shear buckling capacity was observed when opening distance was manipulated. Opening position had no effect on SBC and VR. Opening arrangement had no significant effect on SBC and VR. An optimal section of Z100-19 with 0.3D to 0.5D diamond shaped opening and an opening distance of 100mm centre to centre depending on design engineer's specification is proposed.