Castellated steel beams are those members which are made from hot rolled steel I-section firstly by cutting the web in zigzag pattern and rejoining the two halves by welding together to form a hexagonal castellated beam such that the depth of section will be increased. Generally, the openings made in the web are with hexagonal shape; however, octagonal shape of web openings is typically obtained by providing spacer plate which is utilized to increase the depth of beam. Nowadays, using castellated beams in building construction becomes very popular because of their useful functions such as ease of service provision, strength and low cost. This study focuses on improving the behavior of hexagonal and octagonal castellated beam with spacer plate. The ultimate strength of the original (parent) I- section beam increases due to the increasing its depth. The increment of castellated beam depth; however, leads to post buckling in its web and to many other modes of failure when these beams are subjected for loading. Hexagonal and octagonal castellated beams which are fabricated using parent I-section (IPN140) are analyzed using finite element model (FEM).The analysis results revealed that using ring stiffeners around edge of holes contributes effectively in strengthening the web. It was found that using ring steel stiffeners can reduce the stress concentration around the edge of holes and improve the behavior of these beams by increasing the ultimate strength and minimizing the deflection. From the numerical (FEM) results obtained by using ANSYS14, it is concluded that ultimate strength of castellated beam can be improved by providing spacer plate and ring stiffeners around the web hole. Also, the results showed that ultimate strength of octagonal castellated steel beam can be increased up to (53%) more than the parent beam (IPN140) with providing only (13.0%) weight of steel (spacer plate plus ring steel stiffeners).

This article discusses the experimental testing of tapered castellated beams (TCBs) under mid-span concentrated load. These beams are created by cutting the webs of standard I-sections in a particular zigzag pattern and rejoining the two parts by placing variable expansion plates between web posts and welding them together. Generally, the depth of the mid-span will be increased. A standard I-section (IPE140) was selected as a parent beam to fabricate three TCB specimens and one prismatic castellated beam. The experimental results showed that the ultimate load capacity of the TCBs could be increased up to 140% of the ultimate load capacity of the parent section. Fabricating a TCB is an effective way of increasing the allowable load of a long-span member while remaining within International Building Code-defined deflection limits. The experimental results showed that the allowable load at deflection (L/360) increased up to 183% of the allowable load for the control specimen at the same deflection. Finally, the experimental results showed that web-post buckling and joint-weld rupture failure modes occurred in TCBs due to the formation of high shear forces that tried to twist the web posts.

Castellated beams made by cutting web of hot rolled steel I-section in particular zigzag pattern and recollecting the two parts by welding, to form a castellated beam with hexagonal openings, or more increasing of section depth by placing expansion plates between these parts to fabricate castellated beam with octagonal openings. The main advantage of fabrication this type of beam is increasing section depth, which leads to improve its behavior compared with original beam. So as to use the castellated beams with expansion plates into its best advantages, the failure modes due to web opening need to be avoided. This paper aims to provide added strength of castellated beams with expansion plates by using two types of stiffeners (circular and octagonal ring) around octagonal web opening. This strengthening technique was suggested to reinforce web portion and avoid failure due to web-post buckling. Standard (IPE140) were chosen as a parent section for fabricating four specimens as well as original beam. The important observation through this study is that using ring stiffener leads to have significant effect on ultimate strength. In case of using circular ring stiffeners, the ultimate strength was increased up to (188%) compare with original beam. Whereas the increment in ultimate load at using octagonal ring stiffeners was reach to about (77.6%). Consequent, using circular ring stiffeners to reinforced this type of beams was more efficient than using octagonal ring stiffeners. It is worthwhile to mention that it can be used (37%) as additional steel material (Expansion plates and ring stiffeners) for increasing the load capacity of castellated beams up to (288%) relative to original beam.

Reduced beam section (RBS) behaviours with various cut-flange configurations were investigated numerically in this study. A three-dimensional finite element model material non-linearity was built and validated experimentally, and the impacts of the cut--flange profile on the moment-rotation behaviour and ductility response of moment-resisting connections were investigated in a parametric form. Five-moment connections with various forms of decreasing beam flange were thus modelled using ABAQUS software and compared in terms of cyclic behaviour. RBS with circular, rectangular, trapezoidal, triangular, and drilled holes cut-flange configurations were adopted, and the finite element analysis results showed that radius cut RBS have uniform stress contours, while a re-entrant corner in rectangular, trapezoidal, or triangular cut-flange profiles’ connections may result in stress concentration, resulting in a fracture of the flange. In addition, the numerical testing showed that the RBS connection with a circular cut-flange profile offers a lower rupture index than other connections. Thus, the RBS created using circular cut-flange profiles dissipates more energy than other connections.

Nowadays, use of castellated steel beams (CSBs) has become very common because of their advantageous implementations in construction of buildings. Castellated Steel Beams (CSBs) are those members that are fabricated from standard hot rolled steel (HRS) I- sections by cutting along its web in "zigzag" pattern and thereafter rejoining the two halves on one another by welding together to form a castellated beam, so that generally the depth of  a section will be increased. This research analyses the experimental results of six specimens of castellated steel beams and compares with control beam (Parent section). The purpose of this study is to investigate the effect of hexagonal hole dimensions on the ultimate strength and stiffens response of the castellated steel beam. Also, the effect of number of holes on the behavior of the castellated steel beams that have the same span and ratio of expansion was investigated. All specimens of the castellated steel beam were fabricated from hot rolled steel section (IPE140) and were expanded to (1.56) times the parent section depth. From the test results, it is observed that best dimension of castellated steel beam was (span length to holes space ratio L/S = 8.0); hole depth to Castellated beam depth ratio is h/H=0.56, and hole space to the castellated beam depth ratio is S/H = 1.03. The ultimate strength of the castellated steel beam was increased about (50%) stronger than the original beam.