Butt joints – double-cover types: Which of the following are main types of double-cover butt joints used in riveted steel construction?

Introduction / Context:
Riveted butt joints connect two plates end-to-end using one or two cover plates. Double-cover butt joints are popular because they produce near-symmetric force transfer. The arrangement of rivets (chain or zig-zag) and the governing limit state (shear vs bearing) define common types referenced in exams.

Given Data / Assumptions:

• End-to-end plate connection using double cover plates.
• Rivets used as shear connectors and bearing elements.
• Terminology: chain vs zig-zag patterns relate to rivet pitch and transverse staggering.

Concept / Approach:
A double-cover joint has two cover plates (one on each side of the main plates). The rivet patterns may be chain (aligned) or zig-zag (staggered), and design checks include rivet shear, plate/rivet bearing, net-section tension, and block shear. All listed types are recognized variants of double-cover butt joints.

Step-by-Step Solution:
Identify the joint as a butt joint with two cover plates.Recognize that both chain and zig-zag rivet patterns are used.Note that rivets are primarily designed for shear and bearing; hence “shear-riveted” is a valid descriptive type.Therefore, all listed options are applicable.

Verification / Alternative check:
Standard steelwork texts illustrate double-cover joints with either chain or zig-zag patterns; both are structurally acceptable when pitch, edge distances, and net-section checks are satisfied.

Why Other Options Are Wrong:

• Each individual option is valid; thus the comprehensive correct choice is “all the above.”

Common Pitfalls:

• Overlooking net-section reduction due to stagger and multiple rows.
• Ignoring block shear paths in end connections with short end distances.

Final Answer:
all the above