Title RM29 - Module Exercises - Part 2.pdf ✅

RCD 1: BEAM SERVICEABILITY CODEX BLACKWATCH ENGR. PAUL L. LADESMA Civil Engineer | Materials Engineer 1 | Provisional Project Engineer SITUATION: A concrete beam has a depth of 400 mm and a width of 300 mm. The concrete compressive strength, f’c, is 28 MPa and the tensile strength, ft = 2.8 MPa. Calculate the new cracking moment, kN-m, of the beam section if a 150 mm diameter pipe is cast concentrically within it. A. 24.20 C. 24.05 B. 22.40 D. 22.05 SOLUTION: Solve for Moment of Inertia: Ig = bh 3 12 − πD4 64 Ig = (300)(400) 3 12 − π(150) 4 64 = 1,575.15 x 106 mm4 store → B Solve for cracking moment: ft = Mcr(y) Ig → Mcr = ft( Ig) y Mcr = [2.8 MPa ](B) 400 mm/2 ÷ 106 = 22.05 kN ∙ m Mcr = 22. 05 kN ∙ m

RCD 1: BEAM SERVICEABILITY CODEX BLACKWATCH ENGR. PAUL L. LADESMA Civil Engineer | Materials Engineer 1 | Provisional Project Engineer Determine the steel area of the tension steel, mm^2. A. 300 pi C. 500 pi B. 400 pi D. 200 pi SOLUTION: Step 1. Solve for steel area: As = π 4 (20 mm) 2 ∙ 3 pcs = 300π store → A Pa = 300 π mm2