The surface friction coefficient of the old structural reinforcement repair riveted structure is generally low. Since riveting requires specialized equipment and personnel, riveting is now rarely used. There are currently thousands of riveted old steel bridges in use around the world. There are more than 12,000 railway steel bridges in China, and more than 10,000 riveted steel bridges are in service. Grease-loading bolts are a good way to solve the repair of riveted old steel bridges. It does not require special handling of the original surface, such as sand blasting.

The screw hole required for grease-filled bolts is not high enough and can be 23 mm larger than the nominal diameter of the screw. If the plate thickness and the screw diameter can be maintained at an appropriate ratio, the grease-impregnated Bolt will provide higher resistance than the replaced rivet.

Eliminate internal corrosion. Since the resin is completely filled with voids, it can completely eliminate internal corrosion (also important for new structures). Due to the gap between the corroded steel sheet and the reinforced steel sheet, the amount used will greatly exceed the amount of gap between the filling screw and the wall of the hole. However, this also completely ruled out the possibility of the steel plate continuing to corrode.

New structure construction 1) For friction type high-strength bolt connections, slippage occurs when overloaded. But for grease-loaded bolts, this momentary slip is impossible. Grease-loaded bolts have the ability to withstand short-term overload. 2) If the plate thickness and the screw diameter can be maintained at an appropriate ratio, the grease-loaded bolt without pre-tension can provide the same resistance as the friction type high-strength bolt. 3) If the space for bolting is small, which requires each bolt to provide higher resistance, then a pre-tensioned grease-filled bolt can solve this problem. The resistance of the pre-tensioned grease-bonding bolt is the sum of two parts, one is friction; the other is the resistance provided by the resin.

Therefore, under the more severe connection conditions, a small amount of pre-tensioned grease-filled bolts can provide relatively large resistance. High-strength bolts require specialized equipment to handle the surface to achieve the desired coefficient of friction. If it is to be preserved, the painted surface must also guarantee the coefficient of friction of the design. For grease-loaded bolts without pre-tension, no surface treatment is required to ensure no slippage. High-strength bolts also require special tightening tools to ensure adequate pre-tensioning, which is not required for pre-tensioned grease bolts. Demolition of grease-filled bolts is difficult unless special preparations are made in advance. For example, a special separating agent is used to prevent the resin from sticking to the screw and the hole wall, while the high-strength bolt is easy to disassemble.