Search Log in Home Products Projects Documents About Contact Seismic Lock-Up Devices- Also known as Shock Transmission Units TechStar Lock-Up Device (LUD) sometimes referred to as Shock Transmission Units (STU), creates a rigid link at an otherwise moveable connection. During any sudden load, seismic, braking, train acceleration, ship collision or any other force acting on the bridge that would cause the bridge to move suddenly, the LUD becomes a rigid link and the forces are then transmitted through the structure. The concept is to share the load throughout all piers and abutments. By temporarily creating a rigid link where expansion and contraction normally occur, the bridge can be modeled as completely fixed. In continuous bridges the fixed pier no longer must resist the longitudinal forces as all other piers equipped with LUDs would be fixed during this loading condition. In accordance with AASHTO, all testing is done by independent laboratories to assure the performance of the device. Design Criteria In order to design an LUD, it is necessary to know the following: Rate of expansion and contraction during normal operation Total stroke (mm, in.) of the transmission rod through full range of normal movement Ultimate design force to be transmitted through the LUD Geometry of the surrounding application Design code that is applicable no images were found EXPANSION JOINTS W SEAL BEARING SYSTEMS BASE ISOLATION SEISMIC CABLE STAINLESS STEEL Products Expansion Joints Modular Expansion Joint Strip Seal Joint Finger Joints TechFlex Rubber Joint Seal Patch Repair Kit W Seal Application & Innovation Details and Dimensions Physical Characteristics Installation Bearing Systems Pot Bearing Laminated Bearings Disc Bearings Spherical Bearings Base Isolation High Damping Rubber Bearing Lead Rubber Bearing Testing Seismic STU/LUD Viscous Dampers Cable PWS For Suspension Bridges Parallel Wire Cable Stays Cable For Structures Wire For Suspension Bridges NeoCable Wrap Stainless Steel Reinforcement Bar (SS Rebar) Stainless Steel Wire Projects What We've Built Transbay Transit Terminal (USA) Banegas Bridge (Bolivia) Jamal Abdul Nasser Highway (Kuwait) Temburong Package CC2 (Brunei) River Dee/Don Bridges (UK) Al Wakra Bypass (Qatar) Blaydon Viaduct (UK) Panama Metro Line 2 (Panama) Mohammed Hani Flyover (Bangladesh) Palm Jumeirah Bridge (UAE) San Francisco-Oakland Bay Bridge (USA) Browse our project documents and learn more about where we started and where we're headed. Documents About Partners Worldwide D.S. TechStar, Inc. 1219 West Main Cross Street Findlay, Ohio, USA 45840 P: 001-419-424-0888 | F: 001-419-424-5959 Engineering Sales: Warren | Steve TechStar Asia 668 HuaiAn Road Room Shanghai, China P: 0086 15921332295 Engineering Sales: Del | Sean