代写CIVE215001 Structural Design 1 2023代做Java语言
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Structural Design 1
January 2023
SECTION A - REINFORCED CONCRETE
1. Figure 1(a) represents the cross-section of a deep beam that has been cast monolithically with a 1-way spanning slab. In this case, the beam is continuous over 3 spans and each span is equal to 9m. The span of the 1-way spanning slab, which spans between the beams, is 5m.
(a) Given the following, calculate the effective flange width (beff) of the T-section shown in Figure 1(a) for the first and middle spans. [6 marks]
beff = (bw + beff1 + beff2) where
beff1 = (0.2b1 + 0.1l0) ≤ 0.2l0 ≤ b1 ; beff2 = (0.2b2 + 0.1 l0) ≤ 0.2l0 ≤ b2 (refer to Figure 2 (b))
The beam is subjected to the following loadings:
Permanent action Gk = 50.0kN/m (including self weight)
Variable action Qk = 35kN/m
Ultimate load n = 1.25Gk + 1.5Qk (maximum) Using the coefficients provided in the Formula Sheet;
(b) Calculate all of the support moments as well as the maximum span moments in the first and middle span (maximum load is applied to all spans) [5 marks]
(c) Determine the areas of reinforcement required in the first span and at the first internal support (NOT the end support) based on the beam cross-section shown in Figure 1(a) and the moments calculated in b) above. Sketch the cross-sections making sure that you adhere to the basic detailing rules. [12 marks]
(d) If the load pattern applied to this 3-span beam was ‘Maximum: Minimum: Maximum’, sketch the deflected shape for the 3-span beam. What type of moment could potentially occur at the mid-span of the middle span? [2 marks]
2. (a) For ultimate limit state design, the design strength of concrete in compression is taken to be 0.85fck / Yc, where Yc = 1.5. Suggest two reasons for us needing Yc (use a sketch to illustrate your answer).
Suggest two factors for which the 0.85 reduction coefficient takes account of? Use sketches to illustrate your answers. [4 marks]
(b) For reinforcement Ys = 1.15. Why is the design strength of steel taken to be
fyk / Ys? [1 mark]
(c) Assuming normal (Gaussian) distribution, sketch the graph for: Number of Test Results versus Concrete Compressive Strength. Indicate mean strength and characteristic strength. What percentage of results should fall above the characteristic strength (defined as mean strength – 1.64 standard deviation)? [4 marks]
(d) YG = 1.35 for permanent actions and YQ = 1.5 for variable actions
Why do we apply aY factor to the permanent and variable actions and why are they different values? [2 marks]
(e) For a singly reinforced rectangular sagging concrete beam subject to bending moments, various criteria apply when designing for Ultimate Limit State. For abeam of effective depth d and with tensile reinforcement of area As, explain why the following requirements need to be applied:-
Why is a minimum percentage area of tensile reinforcement required?
Give two reasons for limiting the maximum value of the lever arm, z to 0.95d. [4 marks]
(f) Provided the applied ultimate bending moments are not redistributed, for a truly balanced section, the concrete, at the position where the beam is sagging, reaches its theoretical failure strain ( εc = 0.0035 ) at the top of the beam at the same time that the tension reinforcement reaches its yield strain, εy= 0.00217, determine x/d for this case. [4 marks]
(g) For a singly reinforced rectangular concrete beam in bending, sketch the strain and stress profiles for the following three cases as the moment increases from zero to failure:-
(i) low moment – uncracked section
(ii) working/serviceability moment-cracked section
(iii) initial yield of reinforcement
Show the variation in the depth of neutral axis and give approximate values of stress and strain. All diagrams should be to the same scale in terms of order of magnitude. [6 marks]
SECTION B - STRUCTURAL STEEL
3. An L-shape building has the typical floor plan shown in Figure 3. The floor slab is made of pre-cast concrete spanning in one direction as indicated by the arrows in the figure. All joints can be taken as simple connections so the beams are simply-supported. The beams are assumed to be fully laterally restrained.
The actions to be considered consist of a characteristic permanent load of 4kN/m2 and a characteristic variable load of 5kN/m2 . The weights of steel beams and precast concrete units are included in the above loads.
(a) Calculate the factored design load in kN/m for beam CD which has the span of 7200mm,
sketch the bending moment diagram and shear force diagram and determine the maximum bending moment and shear force. [10 marks]
(b) Select the suitable UKB section size for beam CD with S355 steel grade, by checking the following:
(i) Shear [5 marks]
(ii) Bending [5 marks]
(iii) Deflection [5 marks]
The deflection, δ, of a simply supported beam under uniformly distributed load ‘w’ may be calculated from:
The recommended limiting value for vertical deflections under the characteristic load combination due to variable loads is L/360.
4. This question follows the previous question to design column D. All data in Question 3 are
applicable to question 4. A grade S355 column (at the ground floor) with the length of 4500mm is located at D (shown in Figure 3) to carry the load transferred from Beam CD and Beam DE as shown in Figure 4. A further column (Column K) is located directly above Column D. A 30kN load (after considering the partial factor) is also transferred from column K to column D, as shown in Figure 4. The Beam CD or DE is connected to Column D at the flange on each side. The column K has the same length as Column D (4500mm) and is of the same column section. Ignore the self-weight of columns.
(a) Calculate the design actions for column D
(i) Compression [3 marks]
(ii) Moment as function of column section depth [2 marks]
(b) Select the suitable UKC column section for column D by checking:
(i) Compression [7 marks]
(ii) Combined compression and bending [13 marks]
While checking for combined compression and bending, the kyy, kzy, kyz, kzz should be determined according to Annex B EN 1993-1-1.