No abstract

The construction industry is on the lookout for cost-effective structural members that are also environmentally friendly. Built-up cold-formed steel (CFS) sections with minimal thickness can be used to make beams at a lower cost. Plate buckling in CFS beams with thin webs can be avoided by using thick webs, adding stiffeners, or strengthening the web with diagonal rebars. When CFS beams are designed to carry heavy loads, their depth logically increases, resulting in an increase in building floor height. The experimental and numerical investigation of CFS composite beams reinforced with diagonal web rebars is presented in this paper. A total of twelve built-up CFS beams were used for testing, with the first six designed without web encasement and the remaining six designed with web encasement. The first six were constructed with diagonal rebars in the shear and flexure zones, while the other two with diagonal rebars in the shear zone, and the last two without diagonal rebars. The next set of six beams was constructed in the same manner, but with a concrete encasement of the web, and all the beams were then tested. Fly ash, a pozzolanic waste byproduct of thermal power plants, was used as a 40% replacement for cement in making the test specimens. CFS beam failure characteristics, load–deflection behavior, ductility, load–strain relationship, moment–curvature relationship, and lateral stiffness were all investigated. The results of the experimental tests and the nonlinear finite element analysis performed in ANSYS software were found to be in good agreement. It was discovered that CFS beams with fly ash concrete encased webs have twice the moment resisting capacity of plain CFS beams, resulting in a reduction in building floor height. The results also confirmed that the composite CFS beams have high ductility, making them a reliable choice for earthquake-resistant structures.

This paper illustrates the comparison of aerodynamic forces and coefficients on rectangular tall buildings. The forces and coefficients were obtained using Wind Tunnel Experiment and various international code provisions and standards. Rectangular tall building models selected for the study were made of acrylic sheets with various geometric scales. The models were tested using low-speed wind tunnel for various angles of incidents of wind varying from 0° to 90°. Drag coefficients obtained from experiments were compared with values of mean drag coefficients obtained from codes and practices, (a) IS: 875(Part3): Wind Loads on Buildings and Structures (India, 2015), (b) AS/NZS1170.2:2011, the combined Australia/New Zealand Standard on Wind Actions (Standards Australia,2011); (c) ASCE7–10 (ASCE, 2010); and (d) HKCoP-2019, the Code of Practice on Wind Effects in Hong Kong, (Buildings Department HongKong, 2019). Buildings with the same plan aspect ratio show the same aerodynamic behaviour. Wind tunnel study over-predicts the coefficient values compared to standards and practices. The average coefficient of drag values from codes is in good agreement with wind tunnel data with a deviation of less than 15%. The study also includes an examination of parameters such as pitching moment and its coefficient.