Structural Design Assignment

Flat Slab Design

A.Fig. Q-1 shows a flat slab supported on 450 mm by 450 mm columns arranged on a 6 m square grid. It is 200 mm thick and is provided with a drop panel, measuring 1.55 m by 1.55 m on plan, and 150 mm in depth.  The slab is to  carry a design ultimate load of 20 kN/m2 and is reinforced with H20 bars at a spacing of 150 mm at the top in each direction within a 1.6 m wide strip centered with the column. Given that: fck = 35 MPa; fyk = 500 MPa; average cover to centres of bars = 40 mm; and the lateral stability of the structure does not depend on frame action.

(a)Check the adequacy of the slab thickness to prevent punching  shear  failure on an internal column.

(b)Determine the required punching shear reinforcement.

(c)Sketch the punching shear reinforcement with a plan view and  an  elevation view.

B.Fig. Q-2 shows a two-span road bridge with a carriageway width of 6 m. The bridge deck is free to slide on the abutments at the two ends, A and C. At support B, the deck is rigidly connected to the pier such that the top of the pier is free to rotate and translate longitudinally. Given that: fck = 40 MPa and fyk = 500 MPa.

(a)Show the load arrangement and determine the maximum design axial load, NEd, and horizontal force, HEd, transmitted to the pier at B, due to Group 2 (gr2) traffic load acting together with a permanent action inclusive of self-weight, gk, of 80 kN/m.

(b)Determine and sketch the required reinforcement for the pier if NEd = 4800 kN and HEd = 750 kN. Assume it as a slender column fixed at the base, and ignore bending in the transverse direction. Also, assume d/h = 0.85 and K? = 1.0.

Hint: The fixed end support reaction for a propped cantilever with span L, under uniform load w, is given by R = 5wL/8.