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y=25 N/mm^2
P=3.8
250 165 х 250 LANDING BEAM SIZE 125mm x 350mm 1650 165 나 10@250=2500 - 1500
A double flight longitudinal straight staircase is supported by reinforced concrete beams at both of its ends with an effective span is 4.0 m and the height of the stair is 1.65 m as shown in Figure 4. The flight waist's overall depth and landing thickness are designed to be X mm. The width of going and height of the riser is 250 mm and 165 mm respectively. The staircase designed with concrete grade 30, steel grade 500 with H10-150 and H10- 300 is provided for the main and secondary bar reinforcement. Upon completion of the construction work, it was found that the compressive strength of the tested concrete only achieved Y N/mm², which is lower than the designed strength, and the thickness of landing and waist, X also not sufficient. As a structural engineer: (Refer to Table 4 for staircase design specifications and material properties). (a) Assess the staircase's design bending moment and shear force. Consider the variable load to be P kN/m² and permanent load from finishes, baluster and railing to be 1.0 kN/m²Use the nominal cover of the concrete, Cnom as 25 mm. [9 Marks] (b) Check whether the proposed reinforcement is sufficient to cater the actual concrete characteristic strength of Y N/mm² and steel characteristic strength of 500 N/mm². Comment on your answer and propose a recommendation if required. [7 Marks] (C) Check if the staircase is safe in terms of deflection failures. Comment on your answer and propose a recommendation if required. [6 Marks) (d) Illustrate staircase reinforcement detailing