Question

PROBLEM 2: Design a rectangular beam well inside the tension-controlled zone. Start calculations assuming εt=0.0075

Select b, d and As to resist a factored design moment, Mu = 255 k-ftin the tension-controlled zone.

PROBLEM 2: Design a rectangular beam well inside the tension-controlled zone. Start calculations assuming ε-0.0075 Select b, d and As to resist a factored design moment, Mu 255 k-ft in the tension-controlled zone. Material Characteristics: Compression Strength of Concrete - fc 4,000 psi Yielding stress of steel - fv - 60 ksi Since stirrups are not given, assume they are #4 and use the corresponding typical approximate dimensions. Instructions and additional design constrains: (1) The given value of Mu already includes a good estimate of the own weight of the beam (2) Follow the process presented in section 5.3 of the textbook (pages 209-212). That is, use ε,-0.0075 and ρ¡nitia,-(B1f"J/(4 fj). Use that expression for ρ¡nitia, so your numbers will match the instructor's. (3) While calculating b and d consider b-ad. Where a 0.5 (4) Determine an approximate value h by using typical approximate distances for a single layer of reinforcement. (5) If you use the R value in your process, use the following expression: R = ω *f,r * [1-0.588 ω] (6) After calculating d, increase it to the next half-inch so that h is a full integer inch (odd or even value). This is the adopted value of d- dadopted- (7) Calculate b-a d. Notice here we are using d (not dadopted). (8) After obtaining b, increase it to the next even full inch (not an odd inch number). This is the (9) Obtain As employing the so-called three-step iteration procedure. Be sure to obtain at least two (10) In order to satisfy the required As, select only one layer and one bar size (not 2 or more (11) Check that the selected number of bars fit into the adopted width of the beam, badopted. For this, adopted value of b- badopted accurate decimal digits for As. different sizes). Use only rebars in the #4-#11 range. Also, be sure to select the minimum amount of steel that satisfies that requirement. Do not use excessive reinforcement use table A-5 in the Appendix of our textbook. (12) Check that As,min is satisfied. (13) Check that φ-0.9. For this, obtain the corresponding values of a, c and E: (14) Check the satisfaction of the strength relationship φΜη MU- It should be just satisfied (not excessively). (15) Draw a sketch of the reinforced beam showing all dimensions, number and size of rebars (including an open stirrup).

Answer 1