Economic aspects of weight saving in the design of braced steel frames using BS5950 and EC3

Abstract

Eurocode 3 and BS 5950 code are usually been used to design braced steel frame. The design concept usually based on connections, where simple method associated with pinned-jointed, semi-continuous method associated with semi-rigid joints or partial strength, and continuous construction associated with rigid-joint. Partial strength joints are considered using moment resistance of connections in plastic hinge analysis of the frame. Semi-continuous design method is used instead of simple design method. This makes it achieve many benefits, for example, shallow and lighter beams, and the connections are geometrically simple, thereby producing more robust frames. The method is expected to save frame weight. This study introduces the design of multi-storey steel frame of a series of two-storey, four-storey, six-storey and eight-storey with three-bays for each case. A comparison is made between simple design and semi-continuous design using (BS 5950:2000 Part1) and (BS EN 1993-1-1:2005). This is intended to show the economic benefits of multi-storey braced steel frame design, based on weight saving in the choice of beams and columns. It is assumed that they have slight influence on the total weight of frame. Their weight is identical for all frames. I and H Rolled cross-sections are adopted for beam and column respectively. Flexible end-plate connections are used as pinned connections for simple constructions, while flush end plate and extended end plate with different geometric sizes are used as partial connection. All connections are governed by standardised tables presented by Steel Construction Institute. The results of the percentage weight savings analysed and evaluated based on the effect of changing connection types, and the steel grade from S275 to S355. The results show that semi-continuous design is more beneficial than simple design method for multi-storey braced steel frames with a steel weight saving is in the range of 6.35-18.85% by BS 5950 and 9.37-15.36% by Eurocode 3 according to design variables.