Semana 4

1 Problem 1

The rigid bar CDE, shown in Figure, is horizontal before de load P is applied.Tie rod A is a hot-rolled steel (E=200GPa) bar with a length of 450 and across-sectional area of 300 mm2. Post B is an oak timber (E=12GPa) with alength of 375mm and a cross-sectional area of 4500 mm2. After the 225-kN loadP is applied, determine.

• The normal stresses in bar A and post B

R/ σA=(+)228 MPa σB=(-)44.4 MPa

• The shearing stress in the 20-mm-diameter pin at C, which is in doubleshear R/ τC=68.6 MPa

• The vertical displacement of point D R/ υD=0.513 mm ↓

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2 Problem 2

A1

2-in-diameter alloy-steel (E=30,000 ksi) bolt passes through a cold-rolled

brass (E=15,000 ksi) sleeve as shown in Figure. The cross-sectional area of thesleeve is 0.375 in2. Determine the normal stresses in the bolt and sleeves by

tightening the nut1

4turn (0.020in)

R/ σs=(+)48.8 ksi σb=(-)25.6 ksi

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3 Problem 3

A circular brass bar of diameter d is member AC in truss ABC which has loadP = 5000 lb applied at joint C. Bar AC is composed of two segments brazedtogether on a plane pq making an angle α = 36o degrees with the axis of thebar (see figure). The allowable stresses in the brass are 13,500 psi in tensionand 6500 psi in shear. On the brazed joint, the allowable stresses are 6000 psiin tension and 3000 psi in shear.

• What is the tensile force NAC in bar AC? R/ NAC=5.77 kips

• What is the minimum required diameter dmin of bar AC? R/ dmin=1.08in

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