A W section steel purlin span 6.7 m between roof trusses on centers. The roof is assumed to support a dead load of 880 N/m2 of roof surface including self-weight and a live load of 816 N/m2 of horizontal roof surface projection. The slope of the roof truss is 1 vertical to 2 horizontal and the purlins are spaced 1 m on centers. Use A36 with Fy = 248 MPa. Assume all loads pass through the center of gravity of the section. Sag rods are to be placed at the middle thirds between trusses. Determine the ratio of the actual to the allowable bending stress. DO NOT ROUND-OFF DURING THE COURSE OF SOLVING. ANSWER IN FOUR DECIMAL PLACES.  Properties of W Section  A = 2,887 mm2  d = 192.5 mm bf = 100.7 mm tf = 10.82 mm  Sx = 174,900 mm3 Sy = 36,133 mm3  tw = 6.1 mm  Use the following allowable stresses (NSCP 2001): For bending about strong axis, Fbx=0.66 Fy For bending about weak axis, Fby=0.75Fy

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Design of Concrete beam A rectangular beam has a width of 375mm and has an effective depth of 450 mm. f'c = 25 MPa, Fy = 300 MPa. 1. Determine the moment capacity if it is reinforced with steel area in tension w/ 12-25mmø reinforcement bar. Use 0.9 as moment reduction factor. 2. Determine the depth of stress block if steel in compression As' = 3000 mm² is added with steel covering of 50 mm below the top of the beam. 3. Determine the moment capacity of the beam reinforced for tension and compression. 375 0.85fc' 0.003 450 12-25mm0 bar N.A 265.74 (d-an) T= As Sy Es 184.26

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…