Castellated steel beam is a beam with a regular section cut into half with a particular pattern and regrouped with welding to increase its height compared to the original. This structure element has been developed in building constructions since many years ago. However, its uniform section along the span will make the modification no longer effective in cantilever structure, unless it has additional adaptation. Therefore, in this study, it is proposed to use a castellated steel beam with a tapered shape to be applied as cantilever structures. A steel beam with IWF section 150x75x5x7 is the primary sample type in this research. Some variations were made such as openings angle for 450 and 500, openings space for 50 mm, 70 mm, and 90 mm, openings diameter for 50 mm, 75 mm, and 100 mm, and span length for 2 m, 2.5 m, 3 m, and 3.5 m. Two open-source software namely FreeCAD and LisaFEA were used to draw solid 3-dimensional samples and to conduct the numerical analysis to determine stress and deformation respectively. From the result, it is known that the smallest stresses and deformations can be achieved by a different angle of openings, openings space, and diameter for each span length.
Abstract. Castellated steel beams are made from normal steel beams cut into half with certain pattern and re-jointed to increase its height. This action results in many shapes of openings in its web, one of them being circular. Circular openings of castellated beams can also be implemented with single fix supported structures, but if uniform shape is used, it will reduce its effectiveness. In this paper, adoption of tapered shape on castellated beams with circular openings as cantilever structures will be discussed. This study uses 150x75x5x7 and 200x100x5.5x8 IWF sections with variations of opening diameters, opening spaces, and span lengths. The steel has a yield strength of 400 MPa and the analysis runs with solid element 10-node tetrahedron using the finite element method, by observing Von Mises stress and displacement. Free-licenced software such as LISAFEA 8.0 and FreeCAD are utilized for analysing and drawing solid elements. The result shows that the optimum height of IWF section for 150x75x5x7 is 230 mm and for 200x100x5.5x8 is 318 mm between span lengths of 2 m to 3.5 m. It can be concluded that each of the span lengths has various optimum diameters and opening spaces to acquire the smallest stress and displacement.
Abstract. Cantilever beams are generally used in all infrastructures, including precast concrete structures. In that type of structure, the asymmetric-section shape usage will be optimum and effective. However, in precast concrete structures, it might be susceptible especially in beamto-connection parts due to its strength. In this research, the damage mechanism of connections between cantilever beams and columns in precast concrete will be analyzed. The asymmetric shape will be applied in cantilever beams. Three samples were made with a length of 1500 mm equipped with six 10 mm-diameter deformed rebar and stirrup with 6 mmdiameter plain rebar. The results show that each of the three speciments has its own effectiveness based on stress, strain, displacement, load, and other related parameters.
Concrete is one of the most commonly used materials for construction. Due to the increased of concrete demand, the need for alternative material to substitute natural aggregate becomes crucial. In this study HDPE plastic waste was used as artificial aggregate. HDPE was mixed with natural coarse aggregate at variation of 0%, 10%, 15% and 20%. Compressive test and split tensile tests were performed on concrete age of 28 days. The compressive strength of concrete decreased with the addition of HDPE levels. The result shows that the highest value of compressive strength was 27,88 MPa on 0% HDPE and the lowest value was 11,08 MPa on 20% HDPE mixture. The highest split tensile strength achieved by normal concrete of 2,71 MPa. Split tensile strength of concrete gradually decreased with the addition of HDPE variations. The lowest value of tensile strength was obtained from variation of 20% HDPE plastic waste that is equal to 1.72 MPa. From the analysis it can be concluded that the replacement of coarse aggregate crushed stone with HDPE plastic waste reduce split tensile strength of concrete.
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