Looking forward to the development prospect of bridge construction in the 21st century, sea-spanning bridge construction will be a new theme. With the emergence of advanced philosophy and technology, bridge construction has got development quickly, many countries even have ideas to construct sea-spanning bridges.
The main purpose of developing sea-spanning bridge is to solve transportation among cities. Ferryboat is the primary method at the moment, once sea-spanning bridge is developed, it will bring great convenience and develop local economy.
As for sea-spanning bridge construction, several technical difficulties need to be considered and researched: calculation, earthquake and disaster prevention, durability design.
1. The calculation of sea-spanning bridge.
Bridge structure calculation is always a difficulty during bridge development. Different standards have different calculation method. These difficulties are caused mainly by load and complexity. A bridge maybe got following loads: vehicles’ shocking load, flow impulse force, wind load, unexpected ship collision force, internal force brought by different temperatures and earthquake force, etc.
There are four methods are adopted to analyze calculation data: finite element analysis, transverse distribution coefficient method, weighted method and experimental method. While result of the four methods maybe misfit with actual situation, so the calculation of sea-spanning bridge needs to be perfected.
2. The design of earthquake and disaster prevention.
The research of earthquake and disaster prevention is a question cannot be ignored by designers. They came to a conclusion that bridges’ destruction was almost caused by change of axial direction and transverse direction. It’s main manifestation reflects in the following aspects:
① The superstructure of bridge was unsteady caused by earthquake;
② The foundation soil was liquefied by earthquake and foundation was damaged;
③ Weak substructure was corroded by sea.
Once a link is damaged, the whole bridge will be damaged, that’s the reason why it’s complex to design sea-spanning bridge.
3. Durability design.
The definition of durability is that structures can keep designed capacity within the prescribed period under normal maintenance conditions. If durability of bridge is not enough, the consequences are as following:
① Concrete aspect: crack, erosion, carbonization and alkali-aggregate reaction;
② Rebar aspect: corrosion, alkali-aggregate reaction, stress loss;
③ Bonding aspect: weak bonding stress, lose efficiency and less dense of grouting.
To overcome above difficulties and realize the goal of large-span, light, sensitive and environmental sea spanning bridge, self drilling anchor bolt is now the best choice to support structure. Different materials have different functions and then suitable for different conditions.