Effect of temperature and galvanization on the compressive strength of cold-formed angles

Abstract

An experimental program was conducted at The University of Manitoba to investigate the effect of subfreezing temperatures and galvanization on the compressive strength of cold-formed steel angles. The study involved the testing of 20 cold-formed angles, 55 × 55 × 4 mm, with a slenderness ratio of approximately 70. Equal numbers of galvanized and ungalvanized angles were tested at various temperatures ranging from −45 to 25 °C. The material properties were obtained through 48 standard tension coupon tests conducted at the same temperature range. The results showed that the capacity of the angles measured at temperatures below −40 °C was approximately 8% higher than the capacity at room temperature. Similar results were obtained during testing of the standard tension coupons where the yield and tensile strengths of the steel used were approximately 10% higher at temperatures below −40 °C than at room temperature. On the average, the ultimate capacity of galvanized angles was approximately 9% higher than that of ungalvanized angles. Although the yield strength of the corner coupons was between 13% and 27% higher than that of flat coupons tested at room temperature, the compressive strength of the full-size angles was influenced mainly by the material properties of the flat regions. A comparison of the measured and predicted capacities using the current Canadian standard and American specification indicated that the Canadian standard overestimated the ultimate capacity of the angles by as much as 37%, while the American specification underestimated the capacity by as much as 45%. Key words: angles, cold-formed, galvanized, temperature, compression, ultimate.