- 1 (24.39 KiB) Viewed 54 times
-Materials
f'c concrete = 3,000 psi
reinforced steel fy = 60,000 psi
-Loads
Dead Pd = 27 kips
Live Pl = 16 kips
L= 27 ft
The following is requested:
(10 pts) STRUCTURAL ANALYSIS:Calculate the ultimate point load, ignore the self weight of the beamPlot the moment diagram and identify the maximum negative and positive bending moment.(50 pts) FLEXURAL DESIGN FOR MAXIMUM MOMENT:From the previous step, identify the ultimate maximum (critical) bending moment, that is, the one with the greatest magnitude according to your moment diagram.Propose an initial amount of 35% of the balanced amount.Determine the final dimensions of the beam according to the initial amount and the maximum ultimate moment, to do so assume h = d + 3 in, looking for an h/b ratio of approximately 2. Close the measurements h and b to the nearest inch upwards.Select the steel according to the initial amount.Review of the section: Recalculate "d" according to the final dimensions of the beam, covers and dimensions of the rods, assume stirrup #3 or #4 depending on the selected rod, Verify the ductility, the minimum width required by the selected rods and recalculate øMn.(15 pts) STEEL SELECTION FOR OPPOSITE BENDING MOMENT:With the dimensions of the beam resulting from the previous step, select the steel to support the moment that causes the opposite curvature. For example, if you designed in step 2 for a maximum negative moment you will now calculate the steel for a maximum positive moment, otherwise if you designed in step 2 for a maximum positive moment you will now calculate the steel for a maximum negative moment.Check ductility, the minimum width required by the selected bars and recalculate øMn.
(10 pts) STRUCTURAL ANALYSIS:
Calculate the ultimate point load, ignore the self weight of the beam
Plot the moment diagram and identify the maximum negative and positive bending moment.
(50 pts) FLEXURAL DESIGN FOR MAXIMUM MOMENT:
From the previous step, identify the ultimate maximum (critical) bending moment, that is, the one with the greatest magnitude according to your moment diagram.
Propose an initial amount of 35% of the balanced amount.
Determine the final dimensions of the beam according to the initial amount and the maximum ultimate moment, to do so assume h = d + 3 in, looking for an h/b ratio of approximately 2. Close the measurements h and b to the nearest inch upwards.
Select the steel according to the initial amount.
Review of the section: Recalculate "d" according to the final dimensions of the beam, covers and dimensions of the rods, assume stirrup #3 or #4 depending on the selected rod, Verify the ductility, the minimum width required by the selected rods and recalculate øMn.
(15 pts) STEEL SELECTION FOR OPPOSITE BENDING MOMENT:
With the dimensions of the beam resulting from the previous step, select the steel to support the moment that causes the opposite curvature. For example, if you designed in step 2 for a maximum negative moment you will now calculate the steel for a maximum positive moment, otherwise if you designed in step 2 for a maximum positive moment you will now calculate the steel for a maximum negative moment.
Check ductility, the minimum width required by the selected bars and recalculate øMn.
PL 3 A مد B