You are required to complete a detailed design of an office building. The geometry of the building is shown in Figures 3 and 4. Figure 3 shows an elevation view while Figure 4 shows a typical cross-section of the building; note that some columns run the full height of the building and some (the internal columns) only run from the first floor level to the roof. Design a building with unique loading and geometrical conditions.

Bracing against horizontal actions (e.g. wind loading) is not shown, but its configuration must be chosen and its design conducted as part of the project. Characteristic actions (unfactored loads) on the building are given below as well as further useful information.

Typical floor loading:

Concrete slab on profiled metal decking * to determine*

Depth of slab - 150m

Floor finishes - 0.4 kN/m²

Services - 0.4 kN/m²

Moveable partitions - 1.0 kN/m²

Imposed floor loading - 3.5 kN/m²

Roof loading:

Concrete slab on profiled metal decking *to determine*

Depth of slab - 150m

Floor finishes - 0.4 kN/m²

Services - 0.4 kN/m²

Snow weight (only assumed to apply to the roof) - 0.6 kN/m²

Wind loading (to be factored by 1.5):

Characteristic dynamic wind pressure (transverse and longitudinal face) - 0.5 kN/m²

Density of building materials:

Density of concrete - 2400 kg/m3

Additional notes:

Design calculations should be conducted in accordance with Eurocode 3.

Use grade S355 steel throughout.

Design Data Table

Height of top storey (m)	Height of middle storey X (m)	Height of bottom storey Y (m)	Span of primary beam B4, P (m)	Span of secondary beam S (m)	Span of central beam B5, (m)	Depth of the concrete slabs (m)	Imposed floor loading (kN/m2)
4.5	4.5	6.5	11.3	7	4	150	3.5

The following design steps are required:

1. Distribution and calculation of design loads in beams

Calculate the vertical design loading (1.35 DL + 1.50 IL) on the marked beams (B1, B2, B3, B4 and B5) at a typical floor level and for the roof at a typical cross-section of the building (i.e. not in end frames). Assume the self-weight of the secondary and primary beams is 0.4 kN/m and 0.8 kN/m, respectively.

2. Calculation of maximum design loads in a column

Calculate the maximum design loading in columns C1 and C2 for each storey at a typical cross-section of the building. Assume the following: The column self-weight is 2 kN/m. As before, the secondary beam self-weight is 0.4 kN/m and the primary beam self-weight is 0.8 kN/m. The loading in each column is determined from the reactions in any supported beams and columns, as well as the self-weight of the column itself. The assumed self-weight of the plate girder recommended under point 5 below.

3. Beam design

Design the typical internal beams B1, B2, B3 and B4 at 2nd floor level, using hot-rolled UB sections. Assume the following: All beams are simply-supported. Use a deflection limit of L/200. The roof beams are the same as the Level 2 beams. For practicality, B5 may be taken as the same section as B4

4. Column design

Design the columns C1 and C2, using hot-rolled UC sections, at a typical cross-section of the building. All columns are pin-ended and concentrically loaded.

5. Plate girder design:

Calculate the design loading on the plate girder B6 (at a typical internal cross-section of the building), and hence choose and initial sizing for the web and flanges. Check that the plate girder conforms to the requirements of Eurocode 3. An allowance of 1200 kg/m (unfactored) should suffice for the self-weight of the plate girder.

6. Bracing design

Distribute the wind loading into point loads acting at the roof, 2nd floor and 1st floor levels of the building, and hence choose a suitable bracing configuration show by means of a sketch where the bracing is located. Bracing should be provided in the longitudinal and transverse directions. Design the tension bracing members for one storey on each face you can choose which storey.

7. Joint design

Design a simple beam-to-column joint between B4 and C2 at second floor level, using double angle cleats.

8. Cost estimate

Make an approximate estimate for the total cost of the steel work in the building. Assume that the cost of steelwork including supply, fabrication, transportation and erection is about 925 /tonne for hot-rolled sections. Assume that the plate girder is 1000kg/meter length.

9. Drawings/sketches

Prepare the following drawings/sketches: A plan view of the building with key dimensions labelled. A typical cross-section view of the building with key dimensions labelled. An elevation view of the building with key dimensions labelled. Details of the connection designed with key dimensions labelled.

The assessment of each component will consider clarity of presentation (calculations and drawings) and overall design awareness (practical, economic and sustainability considerations).

Make appropriate assumptions for any missing information. Write a clear and concise discussion of your design approach, how you made the selections and choices that you did, problems encountered. This should show an appreciation of advantages and disadvantages of steel as a structural material in terms of sustainability, vulnerability, constructability, durability, cost effectiveness, structural efficiency.

INCLUDE DETAILS OF THE LOAD COMBINATIONS EXAMINED

Roof B4 B5 B4 4.5 m C1 C2 C2 C1 2nd floor T B4 B5 B4 'X' m C1 C2 C2 C1 1st floor Plate girder B6 'Y' m C1 c1 Ground floor 'P' m 4 m 'P' m Figure 3: Elevation view of the building 'P/2 m 'P/2 m 'P/2 m *P/2 m 4 m 'S' m 1 1 'S' m B4 B5 B1 B2 B3 33_ 1 1 'S'm 6'S' m 1 1 'S'm 1 1 1 1 1 'S'm 'S'm 2'P' + 4 m Slab span direction Columns run full building height Columns run from 1st floor to roof Figure 4: Plan view of the building