Water-pressure test and determination of welding-throat-depth for welded built-up square CFST column

Welding process and throat depth are essential to reduce construction costs of steel tubes. However, the resulting welds should be checked to ensure construction safety especially when wet concrete is to be pumped into the tubes. In the past, tests (Mock-up Test) using actual size specimens were conducted to verify the feasibility of welding throat depth (WTD) during the concrete casting stage on site. However more than often, this is inapplicable owing to the high testing costs, difficulties in disposing of test specimens with wet concrete, and lack of suitable places to conduct tests. Accordingly, this study suggested a water pressure test method and carried out 6 tests on welded built-up square concrete-filled steel tubular (CFST) columns to evaluate the WTD safety. Recommendations are made for the WTD selection.