Search Log in Home Products Projects Documents About Contact STU/LUD TechStar is a worldwide leader in the supply of Shock Transmission Units (STU’s), also known as Lock-Up Devices (LUD’s). A Lock Up Device (LUD) is a plasto-elastic unit that provides the engineer a simple method of temporarily creating a fixed connection, when desirable, that otherwise would remain as a moveable connection. The device is sometimes referred to as a shock transmission unit or LUD. The device is connected to either side of adjoining structures or between elements of structures, where expansion and contraction occur. Upon a sudden dynamic load, the device locks up and transmits the load through the structure. In effect, the device creates a rigid link within a fraction of a second and is modeled as a fixed connection during the shock loading. Once the shock load is removed, the device reverts to its benign influence and the structure behaves in a normal manner. The LUD does accommodate all slow movements associated with a bridge structure such as thermal movement, shrinkage, and creep. STU/LUD Design Requirements Every Seismic Device project is different, the following are details TechStar Engineer’s need to design and quote the Seismic Device for this project. 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 Preference in corrosion protection Notable Projects: Carquinez Bridge Paksey Bridge Geoga Bridge 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