# Design of Steel Structures Questions and Answers – Back-to-Back Connection

This set of Design of Steel Structures Multiple Choice Questions & Answers (MCQs) focuses on “Back-to-Back Connection”.

1. The slenderness ratio of each member when placed back-to-back or separated by small distance shall be
a) greater than 40
b) not greater than 40
c) 0.8 times the slenderness ratio of column as a whole
d) greater than 50

Explanation: Two rolled sections placed back-to-back or separated by small distance should be connected together by rivets/bolts/welds so that slenderness ratio of each member when placed back-to-back or separated by small distance is not greater than 40 or 0.6 times the slenderness ratio of column as a whole.

2. Minimum number of bolts for connecting end of strut is
a) 0
b) 3
c) 1
d) 2

Explanation: Ends of strut should be connected with minimum of 2 bolts/rivets or equivalent length of weld length (length must not be less than maximum width of member).

3. Which of the following is true?
a) when there is small spacing between the two sections placed back-to-back, washers and packing should be provided
b) when there is small spacing between the two sections placed back-to-back, washers and packing should not be provided
c) there should be additional connection in between along the length of member
d) when leg of angles greater than 125mm wide or web of channel is mm wide, minimum bolt is sufficient for connection

Explanation: There should be minimum of two additional connection in between, spaced equidistant along the length of member. When there is small spacing between the two sections placed back-to-back, washers(in case of bolts) and packing(in case of welding) should be provided to make connection. When leg of angles greater than 125mm wide or web of channel is mm wide, minimum two bolts/rivets should be for connection.

4. Minimum diameter of bolt when member is less than 16mm thick is
a) 8
b) 10
c) 22
d) 20

Explanation: Rivets/bolts should not be less than 16mm in diameter for member less than 10mm thick, 20mm in diameter for member less than 16mm thick and 22mm in diameter for member more than 16mm thick.

5. Which of the following is not true?
a) spacing of tack bolt should be less than 600mm
b) spacing of tack bolt should be greater than 600mm
c) if bolts are used, they should be spaced longitudinally at less than 4 times the bolt diameter
d) connection should extend at least 1.5 times the width of the member

Explanation: Spacing of tack bolt should be less than 600mm. If bolts are used, they should be spaced longitudinally at less than 4 times the bolt diameter. Connection should extend at least 1.5 times the width of the member.

6. Members connected back-to-back connected by bolts should be
a) not be used
c) subjected to twice the transverse loading in plane perpendicular to bolted surface
d) not subjected to transverse loading in plane perpendicular to bolted surface

Explanation: Members connected back-to-back connected by bolts should not be subjected to transverse loading in plane perpendicular to riveted/bolted/welded surface.

7. For members placed back-to-back, the spacing of bolt should not exceed
a) 12t
b) 16t
c) 18t
d) 20t

Explanation: For members placed back-to-back, the spacing of bolt should not exceed 12t or 200mm, where t is thickness of member.

8. Longitudinal spacing between intermittent welds used for connection should be
a) greater than 18t
b) greater than 16t
c) not greater than 16t
d) equal to 18t

Explanation: Longitudinal spacing between intermittent welds used for connection should not be greater than 16t, where t is thickness of thinner connection.

Sanfoundry Global Education & Learning Series – Design of Steel Structures.