These methods have many disadvantages that cannot be effective as an expansion joint system. Lack of necessary strength against loads caused by passing vehicles, sheet lifting due to deck vibrations, longitudinal distortion of the sheet, separation of the corner from the deck concrete, rigidity of the simple sheet and corner system, lack of protective heel in the mentioned methods of implementing the expansion joint, most importantly, the lack of water tightness and the possibility of water entering and cementing the expansion joint space during operation have caused the usual methods to not have the necessary efficiency and durability and their useful life is very short.
Unfortunately, despite the many disadvantages of the mentioned systems, it is still observed that consulting engineering companies and bridge construction contractors suggest the above inefficient methods to employers, which lead to significant damage to the bridge structure and are one of the main factors in increasing maintenance costs. In this regard, the use of modern methods for implementing expansion joint systems in concrete bridges in order to improve their quality level and also to utilize internal capabilities, using valuable scientific experiences gained during operation and experimental observations made at Kashan Tire Company, are among the topics on the agenda.
The correct implementation of expansion joint systems is one of the most important implementation details of the bridge deck, which requires great care in its design, operation, and various stages of implementation. If attention is not paid during the construction, installation, and maintenance stages, serious and sometimes irreparable damage can be caused to the bridge structure. Also, lack of care in implementing expansion joint systems can disrupt the smooth flow of traffic. Therefore, it is necessary to pay special attention to the following characteristics in the design and evaluation of the performance of the expansion joint system.
1 – Reducing the adverse effects of the connection of the deck and the roof
2 – No disruption to the thermal performance of the deck
3 – Necessary strength under heavy vehicle wheel loads against high speed and vibrations
4 – Durability against various environmental factors
5 – No disruption to traffic
6 – Having a suitable drainage system and waterproofing
7 – Ease of maintenance
Grouping of expansion joint systems
In a general classification and based on the amount of movable space of expansion joint systems, the following three groups can be considered:
1 – Expansion joint with small displacement (up to 10 cm)
2 – Expansion joint with medium displacement (between 10 and 20 cm)
3 – Mechanical expansion joint with large displacement (more than 20 cm)