In this thesis, the static and dynamic properties of cold-formed Rectangular Hollow Sections (RHS) produced by different manufacturing techniques (direct-forming versus continuous-forming;​ heat-treated versus non-heat-treated) were studied comparatively for the first time. The aim of this research was to quantify the effects of different manufacturing processes on the mechanical behaviour of RHS such that the implications of using RHS with different production histories can be better appreciated during the design of structures made of RHS and their welded joints.

The static properties of seven cold-formed RHS specimens were investigated by performing tensile coupon tests, stub column tests, and residual stress measurements. Analytical column curves were generated to reflect their compression behaviour, based on the experimental results. It was found that, in general, the static properties of a direct-formed RHS are midway between those of its continuous-formed and continuous-formed plus heat-treated counterparts.

The Charpy V-notch (CVN) impact toughness properties of six RHS specimens were studied via 378 CVN coupons. For RHS with different cross-sectional geometries and produced by different methods, complete CVN toughness-temperature curves of the flat face and the corner were compared to quantify the decrease of notch toughness from the flat face to the corner due to uneven degrees of cold-forming. It was also found that heat treatment in accordance with Canadian standards for "Class H" finishing does not provide improvement in the CVN toughness.

The high strain rate properties (compressive and tensile) of four RHS specimens manufactured by different cold-forming methods were examined by performing a total of 166 split Hopkinson pressure/tension bar tests at strain rates ranging from 100 to 1000 s⁻¹. Their dynamic yield stresses were compared to their static yield stresses, to characterize the strength enhancement of cold-formed RHS under such loading rates, which can be used in the blast- or impact-resistant design of RHS members.