D.S. TechStar, Inc. was incorporated in 1990 in the State of Ohio, USA. The founders have over 100 years’ combined experience in developing and engineering bridge related products, such as expansion joints, bearing systems, shear keys and damping systems. Over the past 28 years, TechStar has expanded its fabrication base considerably and today TechStar supports a network of partners around the world producing TechStar Engineered Products for markets in Asia, Middle East, Europe, Africa, Australia and New Zealand, South America, and of course TechStar’s home base in North America.
As TechStar grew, so did their product base. TechStar now supports parallel wire cable products from SPCC in China, having won the cable bid for the Self Anchoring Suspension Bridge in San Francisco. Several other cable structures have been installed recently in North America, Africa and South America. TechStar is proud to be an exporter of USA steel, selling over 20,000 meters of modular expansion joints each year.
Major projects over the world supplied by TechStar Inc. include:
- Palm Jumeirah Bridge (UAE)
- Jamal Abdul Nasser Highway (Kuwait)
- Al Wakra Bypass (Qatar)
- Transbay Transit Terminal (USA)
- Banegas Bridge (Bolivia)
- Temburong Package CC2 (Brunei)
- River Dee/Don Bridges (UK)
- Blaydon Viaduct (UK)
- Panama Metro Line 2 (Panama)
- Mohammed Hani Flyover (Bangladesh)
- San Francisco-Oakland Bay Bridge (USA)
TechStar Joint Systems are designed to withstand the tortures and tests of time and provide for movements up to 2,000mm. The design is based upon AASHTO LRFD unless otherwise stated.
TechStar Joint Systems have been used successfully in over 5,000 installations in over twenty countries. Watertight, fatigue resistant design and proven through years of field experience makes TechStar one of the most recognised names in Joint Design.
The different joint systems available under TechStar include:
- Modular Expansion Joints
- Strip Seal Joints
- Finger Joints
- TechFlex Rubber Joints
MODULAR EXPANSION JOINT
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 a 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 75mm. 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.
Finger Type expansion joints used in bridge construction are an ideal component to accommodate bridge expansion and contraction, while reducing the amount of noise pollution that occurs in other alternative joint types. The primary components of the Finger Type expansion joint consists of steel plates (sliding) that are connected to each side of the road surface’s gap.
Finger Joints are designed within a (fingers of a hand) type of pattern, where the steel plates accommodate movement within one another and allow movement along the axis of the fingers themselves. Since there are no moving parts attached to the joint, cantilever moments reduce the stress induced to the structure. There is a large replaceable gutter below the joint, which is made of reinforced neoprene and provides an efficient drainage system into the bridge’s ducts. The gutter also limits the buildup of standing water to reduce the possibility of vehicles aquaplaning.
TechStar’s finger joints reduce noise pollution, allowing drivers and residential & commercial real estate near the roads where the Finger Joints are applied to enjoy more comfort from noises that occur on the Finger Joint plates.
There are two types of TechStar Finger Joints: TechStar Finger Joint Type A (TSF A) and TechStar Finger Joint Type B (TSF B). TSF A has a movement capacity of 800mm while TSF B has a movement capacity of 120mm (is a noise reduction substitute for strip seal joints). In applications where effective maintenance practices are carried out the TechStar’s Finger Joints will last for a very long time; as such, they offer a very cost-effective and durable solution for most bridge applications. Each and every TechStar Finger Joint is custom designed and fabricated to individual specifications.
Over 30,000 bearings are supplied worldwide.
Bridge Pot Bearings are one type of bearing system used for transferring loads and movements from the deck, to the substructure and foundations. In a highway bridge, Pot Bearing movements are accommodated by the basic mechanisms of internal deformation (elastomeric), sliding (PTFE), or rolling. The mechanical Pot Bearing was the first of a wide variety of bearings that have evolved using various combinations of these mechanisms.
The advanced design of TechStar Pot Bearings is based on the latest developments in bearing engineering and is accomplished with the help of finite element analysis. TechStar Pot Bearings can be designed in accordance with AASHTO Allowable Stress Design, Load Reduction Factor Design (LRFD), BS 5400, DIN standards, or to the Japanese Code (JIS). The detailing of the shop drawings for TechStar Bearings is performed on a modern Computer Aided Drawing (CAD) system that enables the adaptation of Bearings to fit almost any combination of loads, movements, and rotations. Special dimensional conditions can also be satisfied.
Pot-type bridge bearings – fixed or sliding, can accommodate rotations of up to 0.040 radians in any direction and can be designed to accommodate any horizontal load or displacement. A pot bearing consists of a shallow/ hollow steel cylinder, or pot, with an elastomeric disc, slightly shorter than the steel cylinder, fitted snugly inside. A steel disc, or pisto, fits inside the steel cylinder and bears on the elastomeric disc. Flat brass sealing rings are used to contain the elastomer inside the pot. The elastomer behaves like a viscous fluid flowing within the pot as rotation occurs.
Design and Detailing
The advanced design of D.S. TechStar pot bearings is based on the latest developments in bearing engineering and is accomplished with the help of finite element analysis. D.S. TechStar pot bearings can be designed in accordance with AASHTO Allowable Stress Design, Load Reduction Factor Design (LRFD), BS 5400, DIN standards, or to the Japanese Code (JIS). The detailing of the shop drawings for D.S. TechStar pot bearings is performed on a modern Computer Aided Drawing (CAD) system that enables the adaptation of pot bearings to fit almost any combination of loads, movements, and rotations. Special dimensional conditions can also be satisfied.
- Fixed Bearing
- Free Bearing
- Guided Bearing
Spherical Bearings are designed for very high vertical, horizontal and lateral loads and where large rotational structural displacements need to be accommodated. The bearings are grouped into three categories: fixed bearing (restriction of all movement in planar axis); guided bearing (restriction of movement in one direction in planar axis); and multi-directional bearing (allows movement in all planes and axes). All three types can be designed to accommodate uplift loads, often required during construction or the life of the structure. The bearings are designed to be quickly and easily replaced because of the structural fastening and attachment strategy TechStar deploys. Structural rotation is accommodated by a system of convex and concave plates which are, in turn, mounted onto a flat sliding surface which allows horizontal displacements while the curved bearings rotate about their center of the radius.
- Fixed Bearing
- Free Bearing
- Guided Bearing
TechStar supplies many types of bearings to many regions and climates throughout the world. One type, elastomeric laminated bridge bearings (TEB), continues to provide excellent service and quality, proving invariably their efficiency and durability. TEBs have advantages over alternative metallic mechanical bearings, being easier to install, effective in corrosive environments and requiring no maintenance. These advantages are quantifiable in the economics of bridge building.
The design and positioning of the TEB allows for vertical loads (deck and traffic) to be taken by the rubber in compression and horizontal deflections (expansion and contraction) by the rubber in shear. Stiffness is achieved by inserting horizontal metal plates, which do not alter the required low horizontal stiffness. Under maximum traffic and deck load, the amount of vertical deflection must be limited and bearings can be precisely designed so that they do not exceed a few millimeters, of which only a fraction will be due to live load.