04-05 Stiffness and strength of timber beam Jhun Vert Fri, 05/08/2020 - 03:09 pm

Problem 4
The stiffness of a rectangular beam is proportional to the breadth and the cube of the depth. Find the shape of the stiffest beam that can be cut from a log of a given size.

Problem 5
The strength of rectangular beam is proportional to the breadth and the square of the depth. Find the shape of the strongest beam that can be cut from a log of given size.

## 11 Review Problem - Cutting the strongest square timber

Problem 11
Find the waste in cutting the strongest square timber from a circular log of uniform diameter 2 ft. and length 8 ft.

## Solution to Problem 581 | Design for Flexure and Shear

Problem 581
A laminated beam is composed of five planks, each 6 in. by 2 in., glued together to form a section 6 in. wide by 10 in. high. The allowable shear stress in the glue is 90 psi, the allowable shear stress in the wood is 120 psi, and the allowable flexural stress in the wood is 1200 psi. Determine the maximum uniformly distributed load that can be carried by the beam on a 6-ft simple span.

## Solution to Problem 540 | Floor Framing

Problem 540
Timbers 8 inches wide by 12 inches deep and 15 feet long, supported at top and bottom, back up a dam restraining water 9 feet deep. Water weighs 62.5 lb/ft3. (a) Compute the center-line spacing of the timbers to cause fb = 1000 psi. (b) Will this spacing be safe if the maximum fb, (fb)max = 1600 psi, and the water reaches its maximum depth of 15 ft?

## Solution to Problem 539 | Floor Framing

Problem 539
Timbers 12 inches by 12 inches, spaced 3 feet apart on centers, are driven into the ground and act as cantilever beams to back-up the sheet piling of a coffer dam. What is the maximum safe height of water behind the dam if water weighs = 62.5 lb/ft3 and ( fb )max = 1200 psi?

## Solution to Problem 527 | Flexure Formula

Problem 527
In Prob. 526, if the load on the overhang is 600 lb/ft and the overhang is x ft long, find the maximum values of P and x that can be used simultaneously. ## Solution to Problem 526 | Flexure Formula

Problem 526
A wood beam 6 in wide by 12 in deep is loaded as shown in Fig. P-526. If the maximum flexural stress is 1200 psi, find the maximum values of wo and P which can be applied simultaneously? ## Solution to Problem 516 | Flexure Formula

Problem 516
A timber beam AB, 6 in wide by 10 in deep and 10 ft long, is supported by a guy wire AC in the position shown in Fig. P-516. The beam carries a load, including its own weight, of 500 lb for each foot of its length. Compute the maximum flexural stress at the middle of the beam. ## Solution to Problem 235 Statically Indeterminate

Problem 235
A timber column, 8 in. × 8 in. in cross section, is reinforced on each side by a steel plate 8 in. wide and t in. thick. Determine the thickness t so that the column will support an axial load of 300 kips without exceeding a maximum timber stress of 1200 psi or a maximum steel stress of 20 ksi. The moduli of elasticity are 1.5 × 106 psi for timber, and 29 × 106 psi for steel.

Solution to Problem 129 Bearing Stress Jhun Vert Mon, 04/20/2020 - 02:06 pm

Problem 129 A 7/8-in.-diameter bolt, having a diameter at the root of the threads of 0.731 in., is used to fasten two timbers together as shown in Fig. P-129. The nut is tightened to cause a tensile stress of 18 ksi in the bolt. Compute the shearing stress in the head of the bolt and in the threads. Also, determine the outside diameter of the washers if their inside diameter is 9/8 in. and the bearing stress is limited to 800 psi.

Given:
Diameter of bolt = 7/8 inch
Diameter at the root of the thread (bolt) = 0.731 inch
Inside diameter of washer = 9/8 inch
Tensile stress in the nut = 18 ksi
Bearing stress = 800 psi