| Popis: |
In recent years, some reinforced concrete (RC) columns in high-rise buildings, bridges and elevated highways suffered severe damage during strong earthquakes due to brittle and catastrophic shear failure. Under seismic loads, depending on the direction of the ground motion and the connection between the columns and other members, these columns can experience any combination of shear force, axial force, bending moment and torsion. The disastrous collapse of RC columns during the earthquakes motivates a study on the behaviour of RC short columns subjected to multi-directional forces, typical of seismic or wind load. Previous researches prove that low shear span ratio elements are characterized by high strength and stiffness in monotonic or low cycle loading and fail at relatively low deformations, in brittle manner. However, behaviour of relatively high strength concrete rectangular short column under high axial load, especially when torsion is present, is still needs to be further investigated. Many studies have been conducted on prediction of shear strength and finite element modelling of reinforced concrete columns. Nevertheless, the present shear design methods do not consistently provide safe and efficient structures. The present finite element models also do not predict accurately cyclic response of short column particularly under multi-axial loading. Therefore, additional experimental and analytical works need to be conducted. This study consists of three parts. The first part investigates RC short columns subjected to multi-directional loading. Nine identical rectangular columns were tested in shear, torsion or combination of them under high axial load. Cyclic shear force was applied in double curvature mode at different angles to the weak axis of column cross section. Doctor of Philosophy (CEE) |
