Design of Tension Members MCQ with answer and solution

Concept

Shear Lag Effect in Tension Members

Formula

A_net = A1 + k·A2 (where k = 3A1 / (3A1 + A2))

Step-by-step solution

1. Identify the question regarding the reduction of Net Effective Area in an angle section connected by one leg. 2. Recall the concept of Shear Lag, where non-uniform stress distribution occurs because the unconnected leg lags in taking up load. 3. Compare the given options and select Option (c) as the correct answer.

Explanation

When an angle section is connected by only one leg, the pulling force is transferred directly to the connected leg first, while the unconnected leg lags behind in taking up the load. This non-uniform stress distribution across the section is known as the "shear lag" effect, which reduces the effective load-carrying area of the member.

Shortcut

To remember why single-leg connected angles lose effective area, use the rule "One Leg Connected = Shear Lag": - Connected Leg: Takes the load directly and carries primary stress. - Unconnected Leg: "Lags" behind in stress distribution, reducing the net effective area (Anet < Agross).

Common mistake

A common mistake is selecting Option A, as students often attribute any reduction in effective area strictly to bolt hole deductions without accounting for the shear lag effect in single-leg connections. Another frequent error is selecting Option B by confusing tension members with compression members, even though buckling does not occur under tensile loading.