Preliminary Design and Analysis of an Exhibition Centre in Hyde Park - Case Study Example

Preliminary design and analysis of an exhibition Centre in Hyde Park Admission Section Design Section 1 - Drawings Top planFront view Back view Section 1.2 - Description of the structure The building structure proposed in this paper takes shape of a polygon with 12 sides. Despite being situated in an area not prone to earthquakes, it is considered in analysis of the kind of loading the building may be subjected to. A number of considerations are put in place to ensure it meets the objectives of the design. These include: The main structure is made of steel A500grB46. A number of trusses are used as roofing support to shoulder the weight of the roof. Braces are used to support the structure at the joints. The framing of the building generally uses combination of composite beams alongside open-web steel joists which are primarily supported using trusses. Additionally, it uses heavy long span girders in various locations where trusses are not permitted. The deflections of the floor as well as vibration have as well been accorded significant concern, and utilized a concrete slab of thickness 3-1/2 inches. The braced steel frames offer a lateral load resistance for dissipation of seismic energy. In order to arrange braces for the large format truss structure, the structure used truss load paths both for vertical and lateral loading. Nonetheless, there was little option for lateral brace usage. Through strategic selection of locations for lateral resistance proportional to the mass of the building, the system is balanced in line with the building mass, and hence minimizes torsional motion associated with the building. Section 2 - Definition of model and calculations of loads (2 pages maximum in total1) Section 2.1 - Model assumptions The column shown below represents an irregular cross section, and hence was replaced with a simple rectangular section at the ramp South East corner. Walls as well as columns above slab are assigned with joint restraints Half the masses was applied to the roof and other half was applied to top and bottom of columns For area elements, a shell element was chosen due to its translational as well as rotational degrees of freedom, in addition to its ability to support all forces and moments. There is no information with regard to self-weight of hollow slabs and ramp’s slab The concrete slabs as well as the corresponding steel grids are modeled at the same level. Section 2.2 - Applied loads The distribution of both dead and dynamic loading is considered. The dead load basically considers the weight of the roof. On the other hand, seismic and wind loading are considered in analysis of the loading conditions the building is to be subjected. Seismic action effects are evaluated taking into account presence of all gravity loads displayed in following action combination (Ajaya, 2010): Where refers to coefficient combinations for variable action. This combination coefficient is calculated as shown below: Based on the steel profiles as per European standard rolled profiles, the nominal values of yield strength and ultimate tensile strength areas are provided hereafter (CEN, 2004): Dead Loads: Dead loads are made up of the slab weights, beam weights, column weights, and walls. The super imposed dead load incorporates bricks, mortars as well as filling. In this case, the weight is given as, The partitions are made of bricks of 10cm thickness and plastering of 1.5cm from each of the sides. Live loads: The live loads are as specified by the Euro standards, 400 kg/m2. 1 Wind load Assessment of wind load based on Euro standards is made as follows: 1 Wind speed V is appropriate. 2 The speed is multiplied by S1, S2, S3 factors in order to provide the design with a wind speed. 3 The design’s wind speed is changed to dynamic pressure based on the relationship, 4 Dynamic pressure is multiplied by appropriate pressure coefficient Cp in order to provide pressure exerted at any point on building surface. Loads combinations For the case of concrete structures: For the case of steel structures: 1 2 3 Section 3 - Qualitative and approximate analysis Curve Analysis and Design: These are the major equations of the curves: For dead load K1, 2, 3 are constants and are dependent on semi-central angle and the angle at which the stress is measured, are given. For live and snow loads: Meridian stress(C) = -q * R/2d Hoop stress (ζ) = -q * R * (cos 2φc)/2d Whereby, q: uniformly distributed load per square meter on horizontal projection. Φc: the angle measured from the vertical to the point at which the stress is to be measured. K Factors φc k1 k2 k3 0 0.500 0.500 ∞ 10 0.500 -0.480 5.3 20 0.518 -0.428 1.37 30 0.539 -0.330 0.64 40 0.567 -0.210 0.38 50 0.610 -0.035 0.27 51.48 0.620 0 0.26 60 0.668 0.167 0.21 70 0.749 0.404 0.18 80 0.839 0.69 0.16 90 1 1 0.16 Wind pressure on the steel curve point no. Elevation (m) S2 Angle of Inclination Cpe at windward face pressure (N/m²) at windward face Cpe at leeward face pressure (N/m²) at leeward face 1 16 0.646 60˚ 0.433 92.29 -0.633 -29.34 2 16 0.668 37.6˚ 0.366 88.46 -0.46 -20.26 3 16.76 0.688 26˚ -0.2 14.33 -0.4 -14.33 4 17.21 0.702 18.06˚ -0.666 -38.03 -0.4 -14.91 6 17.37 0.708 0˚ -0.8 -76.86 -0.4 -16.17 Wind pressure on the steel columns and trusses. point no. elevation (m) S2 angle of inclination Cpe (win ward face) Pressure (N/m²) at the wind ward face Cpe (leeward face) Pressure (N/m²) at the leeward face 1 17.33 0.666 70˚ 0.8 136 -0.61 -66.2 2 19 0.686 60˚ 0.8 143.5 -0.61 -44 3 20.25 0.700 40˚ 0.25 74.58 -0.432 -19.9 4 20.91 0.706 10˚ 1.25 -163.55 -0.410 -15.1 Section 4 - Selected results of the design and analysis Wind loading Earthquake Just like is the case in calculations, earthquakes show more extreme effect on the building as compared to wind. There is no visible deformation resulting from the wind effect. Rather these effects conforms quantitative analysis findings and remain negligible. See table for details. Φc C dead (ton/m2) ζ dead (ton/m2) C live and wind (ton/m2) ζ live and wind(ton/m2) C total (ton/m2) ζ total (ton/m2) 0 4.60 -4.60 -2.26 -2.26 2.26 -6.76 10 4.66 4.32 -2.26 -0.92 2.30 3.40 20 4.10 2.96 -2.26 1.60 1.86 4.46 30 4.13 2.37 -2.26 2.14 1.88 4.61 40 4.31 1.44 -2.26 0.26 2.06 1.69 60 4.61 0.21 -2.26 -1.94 2.36 -1.73 61.48 4.68 -0.04 -2.26 1.70 2.43 1.66 60 6.04 -1.29 -2.26 -1.83 2.79 -3.12 70 6.63 -3.06 -2.26 0.46 3.38 -2.60 76 6.69 -4.68 -2.26 1.32 4.34 -3.26 All tensional and compressional stresses are less compared to concrete capacity. Beams moments check: The moments as obtained from manual calculations, at mid span of CM2 are: . The moments obtained from sap for the Beam are shown below Figure 1: Shear Force Diagram Figure 2: Bending moment diagram Section 5 - Conclusions The results indicate that the building is self-sufficient. Sap2000 analysis confirms most of the results revealed by manual calculation. Based on all the results, it is evident that response spectrum analysis results compare well to manual results obtained. Nonetheless, sap2000 analysis results show slightly higher values as compared to manual. This is probably explained by varying CQC combination from the sap 2000 analysis. Emphasis should however be placed on the fact that response spectrum analysis is sole approximate approach in multi degree of freedom system analysis. References Ajaya, K. (2010). “Response Spectrum Method – In Seismic Analysis and Design of Structures” CRC Press, Boca Raton, ISBN 0-8493-8628-4 (Obtained from Union College) CEN. (2004). Eurocode 8, Design of Structures for Earthquake Resistance – Part 1: General Rules, seismic actions and rules for buildings. EN1998-1-1:2004, European Standard, Brussels. Read More