Max compressive stress = M/Z
Where M = bending moment and Z = { b×d×d}/6
If we halve the depth then new Z will become Z/4
And stress will become 4x initial value
So option D is correct
A reinforced masonry beam is designed to resist a given bending moment, using the allowable stress...
Problem 2 Design a rectangular reinforced concrete beam to resist a total design moment Mu of 765 ft-kips (this includes moment due to the weight of the beam). The beam size is limited to 15 in. maximum width and 30 in. maximum overall depth. Use fc,-3000 psi and/S-60,000 psi. If compression steel is required, make d'-2.5 in.
2. A rectangular beam, 400 x 600 mm gross dimension, is cast using a concrete strength of fc 30 MPa, reinforced with 5-25 mm diameter steel bar at the effective depth of 500 mm. If is subjected to a moment, M 130 kN-m. Determine the following: Magnitude of the bending moment that cracks the singly-reinforced beam section. (10 pts) b. For the computed cracking moment, determine the maximum compressive stress in the concrete and the stress in the tension steel....
Problem 2 A reinforced concrete beam (see fig.) is acted on by a positive bending moment of M - 160 kNm. Steel reinforcement consists of 4 bars of 28-mm diameter. The modulus of elasticity for the concrete is E = 25 GPa while that of the steel is E, = 200 GPa. (a) Find the maximum stresses in steel and concrete. (b) If allowable stresses for concrete and steel are = 9.2 MPa and 0 -135 MPa, respectively, what is...
1. Design and sketch a reinforced concrete beam to resist a factored design moment of 150 ft.-k. It is required that the beam width be 12 in. and the overall depth be 24 in. fc' 3,000 psi, fy- 60,000 psi. [25-points]
what is the maximum tensile and compressive bending stress in the beam below? Also if allowable bending stress is 10 ksi whats the maximum moment the section can withstand? in M-15 kip-ft 1 in 1 in.
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A reinforced concrete beam with dimensions (300 mm * 800 mm) subjected to a service dead load moment (MD= 500 kN.m) and a service live load moment (ML = 400 kN.m). Design the section as a double reinforced section (the dimensions can't be increased). Place the compression reinforcement at 65 mm from the compression face. Compressive strength of concrete; fc = 28 MPa, yielding stress of reinforcement; fy= 420 MPa. Assume 30 mm to be used in the tension (two...
The reinforced concrete beam shown in Figure-2 is to be subjected to the following uniformly distributed loads over the entire length: DL = 14 kn/m (including self-weight) and LL = 20kN/m, fc = 32 MPa. For architectural reasons the beam width is set at 500 mm. Determine the effective depth required if ku = 0.25 for the section of maximum positive bending moment. Then design the reinforcement required. zin Figure-2
If the beam is subjected to a moment of M = 100 kn-m, determine the bending stress at points A, B, and C. Sketch the bending stress distribution on the cross Section. If the beam is made of a material having an allowable tensile and compressive stress of σallow(T) = 125 MPa and σallow(C) = 150 MPa, respectively, determine the maximum moment M that can be applied to the beam.
all parts A simply supported concrete beam is to be designed to span 8m. The beam is required to resist a dead load of 40 kN/m (which includes an allowance for self-weight) and an imposed load of 20 kN/m Calculate the ultimate design load that the beam will be required to resist and hence calculate the ultimate design moment. (10 Marks] b) Choose an appropriate depth and width of the beam. [5 marks] c) Calculate an appropriate amount of reinforcing...