Expansion Joints in bridge superstructures are provided to
- AAccommodate the thermal expansion and contraction of the bridge deck.Correct
- BIncrease the rigidity of the deck slab.
- CPrevent the bridge from vibrating under heavy traffic.
- DConnect the main girders to the cross-beams.
Solution
Concept
Bridge Expansion Joints
Formula
N/A
Step-by-step solution
1. Identify the purpose of providing expansion joints in bridge superstructures. 2. Recall that expansion joints accommodate the thermal expansion and contraction of the bridge deck due to temperature variations. 3. Select Option A as the correct answer.
Explanation
Expansion joints allow the bridge deck to safely expand during hot weather and contract during cold weather without causing structural stress, cracking, or damage to the bridge.
Shortcut
To remember the primary purpose of Expansion Joints, use the phrase "Expand & Contract, Prevent Stress": - Expand & Contract: Allows the bridge deck to safely adjust to temperature changes (hot/cold weather). - Prevent Stress: Prevents thermal stress, cracking, and structural damage to the deck.
Common mistake
A common mistake is selecting option C by confusing expansion joints with dampeners or bearings meant for vibration control. Another frequent mistake is choosing option B, assuming that joints are added to provide structural stiffness rather than allowing controlled thermal movement.
Correct answer: A) Accommodate the thermal expansion and contraction of the bridge deck.