Freyssinet, Inc. offers its clients a variety
of jacking techniques. These have applications in overcoming problems in
both new construction and existing structures or buildings. Jacks can be
operated vertically to lift structures but also horizontally to move them.
Examples include: bridge lifting and sliding, bearing replacement, high
strength bar tensioning, load transfer, pre-stressing, control of settlement,
force measurement, and weighting. Post-tensioning is a method of reinforcement
employing high-strength steel strands or bars, which enable the existence
of longer clear spans, thinner slabs and in many cases of structural systems
that would otherwise be impossible due to either site constraints or architectural
Conventional hydraulic jacks are available up to 1000 tonnes capacity. They are equipped with swivel heads and locking collars. In addition, Freyssinet, Inc. are able to use their expertise as a bearing manufacturer to add PTFE and elastomer sliding surfaces to the jack head giving it the ability to accommodate limited vertical and horizontal structural movement. The locking collar allows the hydraulic system to be removed once pressurization is complete. Flat jacks are also available up to 1000 tonnes capacity. Flat jacks are uniquely able to operate in gaps of 50 mm or less. In temporary situations, where jack removal is required, inflation can be by hydraulic oil. In situations where a permanent jack installation is required, such as bearing pre-loading or structural lifting, the jack can either be infl ated from the outset with cementitious grout, or transfused under load with grout at a later date.
Jacking forces are controlled by use of either powered or manually operated hydraulic pumps. Mechanical or electronic measurement of hydraulic pressures and structural movements allows the structure to be monitored and carefully controlled as it is jacked. Jacks can be joined together in complex circuits; where they can be operated in unison, in groups or individually.
Freyssinet, Inc.'s in-house temporary works designers are often able to engineer alternative jacking solutions for temporary works where conventional propping systems have been specified. Such solutions often offer considerable advantages in terms of speed, cost, improved access, and do not require temporary foundations or excavation.
Freyssinet, Inc. offers a "one stop" bearing replacement service both on a principal contractor basis and as a subcontractor. Freyssinet, Inc.'s replacement service combines our pre-eminent position as bridge bearing manufacturer and designer with our expertise at design, supply and operation of jacking systems, and our knowledge of speciality construction chemicals such as grouts and epoxies. Other processes such as hydrodemolition and diamond drilling that are regularly required in bearing replacement, are offered as part of the package, supplied by our preferred partners in these specialist trades. Freyssinet's in-house temporary works designers are able to offer innovative alternatives to conventional propping that have time and cost benefits to the client.
Areas of Application: