SRT351 - ASSIGNMENT 1 PART A Jessica Chapman, Darcy Dunn, Harrison Jess, Lyndall Morris

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1 INTRODUCTION This report will examine the effect of different structural methods; steel composite construction and concrete construction, on a high rise floor plan. The design of the floor plan will be used to calculate the load on the critical column for the two structural systems to allow comparison, in an attempt to assess which method is more efficient. Both systems achieve a 1275m 2. ASSUMPTIONS the band beam and slab tables only include for slab depth of 120mm, whereas the brief requires a depth of 180mm. To account for the extra 60mm of slab depth, extra depth was added onto the system- as can be seen in the band beam selection table. the 700mm x 700mm concrete columns specified in both structural systems will be sufficient to support the loads calculated on them. the inter-storey height is 3.8 ENGINEERING SYSTEM SELECTED Band Beam and Slab: This consists of a 180mm deep slab (set by brief), 700x700mm concrete columns (set), a perimeter beam of 300mm wide by 700mm deep (set), and two band beam sizes as shown in the band beam selection table below. Band Beam Selection Source: C&CAA Guide to Long Span Concrete Floors, p. 23 Band Beam Selection Band Beam A -(Green) Band Beam B - (Blue) Span 12.5m 8m Liveload 3.0kPa 3.0kPa Width 1200mm 1200mm Depth 500mm 375mm Added depth for 180 Slab 575mm 450mm Centres/Spacing 4000mm 4800mm Reinforced or Prestressed Prestressed Reinforced 1

2 Steel Beam and Bondek: This option consists of a 120mm deep slab (set), steel Bondek as seen in the Bondek Selection chart below. The columns are concrete 700x700mm (set). There are three steel beam sizes as seen in the steel selection table below. Bondek Selection Source: Lysaght Bondek Design and Construction Manual, p. 12 -Three spans -Visual appearance important -0 props -120mm slab depth -2850mm clear span -Base Metal Thickness 1.0mm Steel Beam Selection Source: OneSteel Span Tables for Simply Supported Beams, p. 2 2

3 Steel Beam Selection Beam A Beam B Beam C Span 12m 12m 8m Liveload 3.0kPa 3.0kPa 3.0kPa Beam Designation 710WB UB UB40.4 Primary/Secondary Primary Secondary Secondary Depth of Beam 716mm 453mm 307mm Width of Flange 250mm 190mm 166mm Self Weight 130kg/m 67.1kg/m 40.4kg/m COLUMN AND BEAM LAYOUT RATIONALE Centres/Spacing 8m 2.8m 2.8m The justification of the column and beam layout in our floor plan was dictated by the need to provide a column free net lettable area. The centralised core position and floor plan dimensions allowed for beam configuration to typically meet the maximum spans allowed for each beam type, eliminating the need for internal columns and two-way slab systems. The free spans allow the space to be arranged to suit an open plan office, various layouts of cellular offices and different variations of these throughout the whole building. The beams spanning from core to the perimeter facade gives flexibility, leading to a fully adaptable building design. Beam and column placements were dictated by the constraints of the materials, through the various maximum spacing and spans allowed for each material as well as the dimensions of the floor plan. For Band Beam construction, the beam layout was limited to a maximum spacing of 4.5 meters and concrete span tables were used to determine the allowable span for each beam size selected. These constraints required the band beams to span the shortest distance-from the core to the façade. The Steel beam layout was tailored to conform to steel s optimal design efficiency and the use of the steel size/span tables aided in determining the spacing and sizes of the beams. These were also spaced so that Bondek with no propping could be used. Column location for both construction methods was determined by the maximum allowable spans of the perimeter beams, and the desire to be as efficient with materials as possible. To optimise the use of space meant designing the structure to span from the core to the façade columns, in order to do so the material constraints were taken into consideration for both construction techniques so as to implement a column and beam layout that was structurally sound, but utilised as little material as possible. 3

4 CRITICAL COLUMN AND LOAD TRANSFERS The following figures are the final calculations of the load on the critical column for each structural system and its corresponding beam and column layout. Band Beam and Slab Option Critical Column: C10 Steel beam and Bondek Option Critical Column: C9 B kN B kN B kN B kN B kN B kN Column 54.74kN Column 54.74kN TOTAL 1,015.36kN TOTAL kN SUPPORTING CALCULATIONS The supporting calculations are provided in Appendix 1- Calculations. DRAWINGS The supporting drawings (floor plans and profiles) are provided in Appendix 2 - Drawings. EVALUATION OF THE TWO APPROACHES Concrete Steel Pros Shallower beam depth of 575mm. Allows for more storeys at the same overall height of the structure. Reducing material costs. Longer spans can be achieved Higher fire rating Cons Pros 1.0BMT Bondek sheeting without the need of propping. More efficient method in terms of construction time without propping. Bondek provides a temporary trafficable work platform More efficient construction as there is no curing time for the structural members. Beams are fabricated offsite Cons Requires 6 additional columns Curing time increases construction time Beams have to be formed on site - lower quality controls Concrete requires propping and formwork during construction. Steel construction consumed 700mm ceiling to floor space with large primary beams - larger than concrete Some beams will require welding onsite in order to fix them to the structure. The steel option results in deeper beams, this reduces the number of storeys that could be included in a height restricted building. So if the number of storeys is critical in a proposed building, then this method would not be preferable. Otherwise steel provides some compelling benefits over concrete, allowing for faster construction times, less work on site and no need for temporary propping. 4

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