PREVENTION OF CRACKS AT CONNECTIONS BETWEEN LIGHT GAUGE STEEL COLUMN AND LIGHT WEIGHT BLOCK WALL SYSTEM

Abstract

Real estate industry in Thailand has increased using the cold-rolled Light gauge steel due to its excellent properties such as lightweight, rusting and corrosion protection, high yield strength, quick and easy installation, which results in economic construction and less environmental impact. Currently, building structural system consisting of steel and reinforced concrete columns have been substituted by the system of light gauge steel columns connected with the lightweight block wall panels. However, several surface cracks have been found at joints between the light weight block walls and the light gauge steel columns. These cracks are thought to be due to higher tensile stress than the strength of material at joints. These stresses can be caused by wind force, expansion and shrinkage of material due to changes of temperature and humidity, vibration from construction, trucks or vehicles, and etc. This research studies on comparison of stresses at joints between various cases of FE modeling structural analysis and experiments. The experiments were to measure bending stress capacity at joints between the lightweight block wall panels connected with the light gauge steel column. The bending stress capacity is used as an allowable tensile stress at joint surface. The compared results from the structural analysis were performed under load cases of wind force, temperature change, and traffic vibration which were measured as velocity at wall surface during construction and acceleration at building base. The results show that the connection between light gauge steel columns and light weight block wall panels using dowel bars or metal straps increases the strength at joint as well as applying the square wire mesh at joint for block plastering work. However, for condition with all load combinations including dead load, live load, wind load, temperature change and traffic vibration, all cases of present connection between light gauge steel columns and light weight block wall panels have not enough strength to prevent crack. The recently used connection can increase joint strength to prevent crack only for usual condition of combination between dead load, live load and traffic vibration. If wind force or temperature change is presented, more dowel bars or metal straps are necessary, even if additional structural components may be needed to be considered.