Flexural Behaviour of Different Stiffener Section Area on Full Height Rectangular Opening Castellated Steel Beam

Vierendeel is one of failure mechanisms in a castellated steel beam. Vierendeel mechanism is the main failure that occurs in a full high rectangular opening castellated beam. Vierendeel decrease castellated flexural capacity compare to the original wide flange section beam. One solution to prevent the vierendeel mechanism is by installing a diagonal stiffener in form of a steel bar on a castellated beam. The research’s purpose is finding the effect of different size of steel bar diameter on the flexural capacity. Four different sizes of steel bar diameter used in this research: 10 mm, 12mm, 16 mm, and 19 mm. Castellated beam flexural capacity is analysed with the method of truss analysis and pushover analysis. This study shows it can be infer that the bigger size of steel bar diameter does not always determine the higher flexural capacity of the castellated beam. Optimum value of the beam’s flexural capacity is affected by the strength of the flange section. The largest increment of flexural capacity between original wide flange compare to the castellated beam is 139.4% by using 16 mm diameter of the diagonal stiffener.

The axial capacity of a full height rectangular opening castellated steel beam with steel reinforcement stiffeners

The axial capacity of a full height rectangular opening castellated steel beam with steel reinforcement stiffeners is proven to prevent Vierendeel failure mechanism. The effect is an increase in flexural capacity of the structure. Diameter of the steel reinforcement stiffeners is revealed to have an effect on its strength in resisting axial forces occur in the structure. However, size of the diameter is limited to the strength maximum value of the steel flange section in withstanding the moment force. Using optimal design of the castellated steel structure, this research aimed to find out the increase value of the axial capacity. There were two models of steel structures employed in the study, IWF 200x100x5.5x8 and castellated beam 362x100x5.5x8, both were loaded with axial directions. Analyses were conducted using truss and pushover methods. Results of the study showed an increase in both flexural (36.81%) and axial (60.78%) capacities. The increase in the value of structure capacity mainly influenced by the stiffeners shortened the effective length of the structure.

Experimental study for improving behavior of castellated steel beam using steel rings

Castellated beams are made from a hot rolled steel I-section in a few steps. Firstly, the web of the parent I-section is cut in a particular zigzag pattern and the two halves are reconnected by welding to form a castellated beam with hexagonal openings. In other cases, a spacer plate is placed between the two halves to produce octagonal openings, which increase the section depth. Increasing the depth by adding spacer plates leads to web-post buckling. This study focuses on improving the castellated beam to obtain high strength with relatively low cost by placing a steel ring inside the octagonal openings to strengthen the weakest part, which is its web. The results show that the steel ring is effective in strengthening the web-post.