1. Product Overview VHC spherical Bearings/ Bridge bearing manufactured by Vinh Hung Investment and Production Company Limited (Vinh Hung IP) are capable of withstanding the high loads and movements suitable for structures requiring the rotary angle equal or bigger than 0.015 rad in all directions. VHC spherical bearings are designed and manufactured according to current standards such as: TCVN 11823, AASHTO LRFD, ASTM D5977, EN 1337, 2. PRODUCT CHARACTERISTICS VHC spherical bearings/ bridge bearing possesses a bottom plate (6) which has a PTFE sliding plate (4) on it is upper curved surface. A convex calotte (5) is placed on top of this, which, thanks to it is polished hard-chromium plated surface, can slide within the lower part with low friction, thus facilitating rotations about every axis. A second sliding plate of PTFE (4) is recessed into the upper surface of the calotte. Together with the upper plate (2) above it, this accommodates longitudinal and/or transverse sliding movements of the superstructure, if required. To reduce sliding resistance to a minimum, the lower surface of the top plate features a polished stainless steel sheet. In the case of bearings which should allow movement along one axis only, the direction of movement is controlled by guiding bars (3). In the case of fixed bearings, the top plate does not have a stainless steel sheet. The bearing is connected to the superstructure and the substructure by means of anchor dowels (1) or threaded sleeves (depending on design), or alternatively by means of separate anchor plates with shear studs. To ensure the long-life durability, VHC spherical bearings are protected against corrosion by the following methods: coating with two-component epoxy, PU-based painting (Polyurethane), hot-dip galvanization according to ASTM A123 standards and especially the Al-Mg spray coating method (at the ratio of 5% Al and 95% Mg) which ensure the anti-corrosion durability of up to 100 years, this method is proved by the salt-spraying test in 6000 hours (8-hour dry-wet cycle) according to ASTM B117
