Q3(a) A wood beam with a rectangular section is found to have the insufficient load capacity. So an engineer decides to reinforce this wood beam by using an aluminum channel section. The original wood beam has a cross section of dimensions 150 mm x 250 mm. The reinforcing aluminum channel has a uniform thickness of 6.5 mm. Other dimensions are in Figure Q3(a). If the allowable normal stresses in the wood and aluminum are 8 MPa and 38 MPa, respectively, and if their moduli of clasticity are 10 GPa and 70 GPa, respectively. What are the maximum allowable bending moments of the beam before and after the reinforcement? 150 mm- 250 mm O. 38 mm 6.5 mm 165 mm- Figure Q3(a)

Q3(a) A wood beam with a rectangular section is found to have the insufficient load capacity. So an engineer decides to reinforce this wood beam by using an aluminum channel section. The original wood beam has a cross section of dimensions 150 mm x 250 mm. The reinforcing aluminum channel has a uniform thickness of 6.5 mm. Other dimensions are in Figure Q3(a). If the allowable normal stresses in the wood and aluminum are 8 MPa and 38 MPa, respectively, and if their moduli of clasticity are 10 GPa and 70 GPa, respectively. What are the maximum allowable bending moments of the beam before and after the reinforcement? 150 mm- 250 mm O. 38 mm 6.5 mm 165 mm- Figure Q3(a)

Mechanics of Materials (MindTap Course List)

9th Edition

ISBN:9781337093347

Author:Barry J. Goodno, James M. Gere

Publisher:Barry J. Goodno, James M. Gere

Chapter5: Stresses In Beams (basic Topics)

Section: Chapter Questions

Problem 5.8.8P: A beam of rectangular cross section (width/) and height supports a uniformly distributed load along...

See similar textbooks

Similar questions

A cantilever beam(Z, = 6 ft) with a rectangular cross section (/> = 3.5 in., h = 12 in.) supports an upward load P = 35 kips at its free end. (a) Find the state of stress ((7T, o^., and r in ksi) on a plane-stress element at L/2 that is i/ = 8 in. up from the bottom of the beam. Find the principal normal stresses and maximum shear stress. Show these stresses on sketches of properly oriented elements. (b) Repeat part (a) if an axial compressive centroidal load N = 40 kips is added at B
A retaining wall 6 ft high is constructed of horizontal wood planks 2.5 in. thick (actual dimension) that are supported by vertical wood piles of a 12 in, diameter (actual dimension), as shown in the figure. The lateral earth pressure is pt=125 lb/ft2 at the top of the wall and p2= 425 lb/ft2 at the bottom. Assuming that the allowable stress in the wood is 1175 psi, calculate the maximum permissible spacing s of the piles. Find the required diameter of the wood piles so that piles and planks (f = 2.5 in.) reach the allowable stress at the same time. Hint: Observe that the spacing of the piles may be governed by the load-carrying capacity of either the planks or the piles. Consider the piles to act as cantilever beams subjected to a trapezoidal distribution of load, and consider the planks to act as simple beams between the piles. To be on the safe side, assume that the pressure on the bottom plank is uniform and equal to the maximum pressure.
Solve the preceding problem if the diameter is 480 mm, the pressure is 20 MPa, the yield stress in tension is 975 MPa, the yield stress in shear is 460 MPa, the factor of safety is 2,75, the modulus of elasticity is 210 GPa, Poissorfs ratio is 0.28, and the normal strain must not exceed 1190 x 10" . For part (b), assume that the tank thickness is 8 mm and the measured normal strain is 990 x 10~ .
A copper bar of rectangular cross section (b = 18 mm and k = 40 mm) is held snugly (but without any initial stress) between rigid supports (see figure). The allowable stresses on the inclined plane pq at mid-span, for which ?? = 55°. are specified as 60 MPa in compression and 30 MPa in shear. (a) What is the maximum permissible temperature rise AT if the allowable stresses on plane pq are not to be exceeded? (Assume a = 17 × 10-6/oC and E = 120 GPa.) (b) If the temperature increases by the maximum permissible amount, what are the stresses on plane pq? (c) If the temperature rises AT = 2SoC how far to the right of end A (distance BL, which is expressed as a fraction of length L) can load P = 15 kN be applied without exceeding allowable stress values in the bar? Assume that a =75 MPa and t = 35 MPa.
A punch for making a slotted hole in ID cards is shown in the figure part a. Assume that the hole produced by the punch can be described as a rectangle (12 mm X 3 mm) with two half circles (r = 1.5 mm) on the left and the right sides. If P = 10 N and the thickness of the ID card is 1 mm, what is the average shear stress in the card?
A cantilever beam with a width h = 100 mm and depth h = 150 mm has a length L = 2 m and is subjected to a point load P = 500 N at B. Calculate the state of plane stress at point C located 50 mm below the top of the beam and 0,5 m to the right of point A, Also find the principal stresses and the maximum shear stress at C. Neglect the weight of the beam.
At a point on the web of a girder on a gantry crane, the stresses acting on the x face of a stress element are s= 6250 psi and ??xy= 1425 psi (see figure). What is the allowable range of values for the stress ??. if the maximum shear stress is limited to t0 = 2150 psi?
A plastic bar of rectangular cross section (ft = 1.5 in. and h = 3 in.) fits snugly between rigid supporls at room temperature (68oF) but with no initial stress (see Figure). When the temperature of the bar is raised to 160oF, the compressive stress on an inclined plane pq at mid-span becomes 1700 psi. (a) What is the shear stress on plane pq? (Assume a = 60 × 10-6/*t and E = 450 × 103psi.) (b) Draw a stress element oriented to plane pq and show the stresses acting on all laces of this element. (c) If the allowable normal stress is 3400 psi and the allowable shear stress is 1650 psi. what is the maximum load P (in the positive x direction), which can be added at the quarter point (in addition to thermal effects given) without exceeding allowable stress values in the bar?
A tie-down on the deck of a sailboat consists of a bent bar boiled at both ends, as shown in the figure. The diameter dBof the bar is 1/4 in., the diameter D Wof the washers is 7/8 in., and the thickness is of the fiberglass deck is 3/8 in. If the allowable shear stress in the fiberglass is 300 psi, and the allowable bearing pressure between the washer and the fiberglass is 550 psi, what is the allowable load P allowon the tie-down?
A beam of rectangular cross section (width/) and height supports a uniformly distributed load along its entire length L. The allowable stresses in bending and shear are and TaUow, respectively. If the beam is simply supported, what is the span length Lübelow which the shear stress governs the allowable load and above which the bending stress governs? If the beam is supported as a cantilever, what is the length L() below which the shear stress governs the allowable load and above which the bending stress governs?
A solid circular bar of steel (G = 78 GPa) transmits a torque T = 360 N - m. The allowable stresses in tension, compression, and shear arc 90 MPa, 70 MPa, and 40 MPa, respectively. Also, the allowable tensile strain is 220 x 10-6, Determine the minimum required diameter d of the bar, If the bar diameter d = 40 mm, what is Tmax?
A W 360 x 79 steel beam is fixed at A. The beam has a length of 2.5 m and is subjected to a linearly varying distributed load with maximum intensity q0= 500 N/m on segment AB and a uniformly distributed load of intensity qQon segment EC. Calculate the state of plane stress at point D located 220 mm below the top of the beam and 0\3 m to the left of point B. Find the principal normal stresses and the maximum shear stress at D. Include the weight of the beam, See Table F-l(b), Appendix F, for beam properties.