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The Modular Expansion Joint System (MEJS) is a mechanical device installed in bridge expansion joint openings. The primary function of the MEJS is to permit vehicle traffic to travel smoothly across large expansion joint openings. It does this by dividing the large expansion joint openings into a series of smaller openings called cells. These cells work in series to accommodate the necessary thermal bridge movement (expansion and contraction) while providing a smooth riding surface for bridge vehicle traffic. The MEJS is normally used for expansion joints with a movement range exceeding 75 mm. The MEJS also has the secondary function of protecting the surrounding bridge superstructure and substructure. All MEJS cells are equipped with watertight sealing elements that prevent debris, water, and corrosives such as de-icing chemicals from passing through bridge expansion openings and damaging superstructure and substructure components.
Movement Range – The movement range of the MEJS is accommodated by the planned operating range of the neoprene seal and by the number of seals. That is, if the planned operating range of the neoprene seal equals 80 mm, the LG12 MEJS achieves a movement range of 960 mm (12 × 80 mm = 960 mm).
Joint Width – The joint width “f” in the below table is variable. It changes with MEJS movement. Joint width fmin is the width of a closed joint. Joint widths f60, f70, and f80 are the widths of the fully open joint. That is, each element has a gap of 60 mm, 70 mm, 80 mm according to the planned operating range. Thus for an LG6 MEJS, there is a difference between fmin and f80 of 480 mm (6 × 80 mm = 480 mm).
Weight – The MEJS weights “G” shown in the below figure are mean values that vary, depending on design details
Steel Beams – TechStar uses two standard beam profiles, consisting of a 140mm tall x 70mm wide I-shaped beam & a 120mm tall x 80mm wide I-shaped beam. Both beam profiles are of the same steel grade. The beams to be used for an individual project are determined by availability, blockout dimensions, project location and other factors.
MEJS sizes with 140mm x 70mm beam:
MEJS sizes with 120mm x 80mm beam:
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