Question

A 3x8 member in a diaphragm resists a tension force caused by the lateral wind pressure. Lumber is Select Structural DF-L. A single line of 7/8-in. diameter bolts is used to make the connection of the member to the diaphragm. Cm=1.0, Ct=1.0, and Ci=1.0. Find: a. The maximum axial tension load using ASD. b. The factored axial tension capacity using LRFD.

Answer 1

The width of member is as follows:

b = 3 ft

b = 3 × 12 in.

b= 36 in.

The depth of member is as follows:

d = 8 ft

d = 8 × 12 in.

d=96 in.

Since the structure used is Douglas fir-Larch lumber of size 3 × 8 size. Hence, tensile strength, f =1000 psi

Calculate the net area of the member as follows:

A = (b - ∅) × d

A= (36 - 7/8) × 96

`A=3372 in^(2)`

Calculate the maximum axial tensile load by ASD method as follows:

P = f × A

P = 1000 x 3372

P = 3372000 lbs

P = 3372 kips