Prob. 1 Four 50 mm x 200 mm dressed planks are used to carry a super imposed load of "W" kN/m. The allowable bending stress of the plank is 8.30 MPa. How should the four planks be framed to give the maximum stiffness as a beam? Determine also the safe uniform "W" kN/m that this beam could carry if the span is 6 m and is assumed to be simply supported. diagram 1 40.5 40.5 40.5 40.5 187.50

The section of a Super-T prestressed concrete girder is shown below. The girder is simply supported on a span of 7.0 m and are pre-tensioned with total initial force of 825 kN from low-relaxation strands. The girder supports a total dead load of 2 kPa and live load of 6 kPa. There is a loss of prestress of 0.2 at service loads. Assume "-" for compression and "+" for tension. Hint: Assume tributary width is equal to flange width. Properties of the section: A = 100,000 mm2 INA = 940 x 106 mm4 All measurements in the drawings are in millimeters. 1. What is the stress, in MPa, at the top fibers of the girder at end span due to initial prestressing force only? 2. What is the stress, in MPa, at the bottom fibers of the girder at midspan due to initial prestressing force only? 3. What is the stress, in MPa, at the top fibers of the girder at end span due to prestressing force and service loads? 4. What is the stress, in MPa, at the bottom fibers of the girder at midspan due to prestressing…

A simply supported wood beam that is 13.5 m long carries a 36 kN concentrated load at B. The cross-sectional dimensions of the beam are b- 155 mm, d- 390 mm, a - 65 mm, and c- 30 mm. Section a-a is located at x- 2.3 m from B. (a) At section a-a, determine the magnitude of the shear stress in the beam at point H. (b) At section a-a, determine the magnitude of the shear stress in the beam at point K. (c) Determine the maximum horizontal shear stress that occurs in the beam at any location within the entire span. (d) Determine the maximum tensile bending stress that occurs in the beam at any location within the entire length. |P H d a В C L 2L 3 Answer: (a) TH - 0.33 kPa (b) TK - i 0.169 kPa (c) Tmax - 0.595 kPa (d) Omax" 27.486 MPa 3

Flexural Stress