CIVL2230 INTRODUCTION TO STRUCTURAL CONCEPTS & DESIGN Assignment A1

(Due: 4:00PM, Thursday, 12 August, 2010) Gravity loads (dead and live load)

Question 1(review of structural mechanics) The beam shown in the figure is subjected to 2 point loads,

1. What are the reactions at each support? 2. Draw the shear diagram due to the given loading. What is the maximum shear for the beam? 3. Draw the moment diagram due to the given loading. What is the maximum bending moment for the

beam?

1.0 m

A

P1=20 kN

B

1.4 m 1.6 m

P2= 20 kN

Question 2 A simply supported steel beam spans 12 m and carries a uniform dead load of 7 kN/m and a live load of 14 kN/m. What is the maximum deflection in the beam due to the total dead load and live load? Australian Standard for Steel Structures (AS4100) suggests the total deflection under dead and live load should be limited to L/250 (L is the length of the beam.) Is this deflection serviceability requirement satisfied? (The Young’s modulus for steel is 200000MPa. The second moment of area for the beam section is 760×106 mm4) Question 3 The typical floor plan of a 20-story office building is as shown in the following figure. The storey height, top of slab to top of slab, is 4.0 m. Roof and floors consist of 130mm thick normal weight concrete slab. See section A-A, B-B and C-C for beam size. (Unless noted otherwise, live load reduction is not permitted.) Showing all working which must be neat and clearly set out, answer the following: (a) Estimate permanent and imposed actions on the slabs, as distributions in kPa. Assume the weight

of the floor finish, ceiling, service pipes and partition (i.e., superimposed dead load) is 1.5 kPa. (b) Calculate permanent and imposed actions on a typical junior beam (Beam “B1” in the plan). (c) Calculate permanent and imposed actions on a typical girder (Beam “B2” in the plan). Assume the

girder is simply supported; calculate the maximum bending moment and maximum shear in the girder under the dead load and live load, respectively.

(d) Calculate permanent and imposed actions on the edge column “C1”, at ground level. Assume its diameter is 900mm. Provide two solutions, one with and one without live load reductions.

The density of normal weight reinforced concrete may be taken as 2,500 kg/m3. (Hint: the concrete slabs are supported on junior beams (Beam “B1” in the plan). The junior beams are supported by the girders (Beam “B2” in the plan.)