Cable-stayed bridge at St. Petersburg - continued
The 620 m long bridge across the Korabelny channel, St. Petersburg, Russia
Premiere for Heavy-duty bracket HDC
While the piers are built with the MF240 climbing formwork, the pier heads presented a particular challenge for the project team.
For the first time the experts of the Competence Center for Bridges put into action the HDC heavy-duty bracket that was tailored to the project-specific requirements. The system has an especially high load capacity, it is modular and versatile in its use.
A total of 1,000 kN can be transferred by one heavy-duty bracket compared to 310 kN when using conventional supporting construction frames.
With a suspension shoe, the brackets can be used for structure inclinations up to 22°.
The bracket is 4 m long and, if necessary, can be extended by using supporting construction frames. The heavy-duty bracket used for the Korabelny Bridge measures a total of 12 m.
Halfen tie rods used to screw on the suspension shoe for the bracket are embedded in the last casting section of the pier shaft.
Two brackets, each consisting of a basic and attachable frame, are connected by horizontal and diagonal bracing. They are hung into the suspension shoes and secured as a pair of brackets.
The entire unit, including the mounted formwork, can be levelled with a hydraulic cylinder. The total lift enabled by the lock nut cylinder is 100 mm. An upward adjustment of 20 mm is possible, while the bracket can be lowered up to 80 mm during stripping.
Spindles at the bottom of the entire frame ensure that loads are transferred into the pier. A total of 500 m² formwork is used for the pier heads.
Precast Concrete Vibrators
Cougar Concrete Form Vibrators from Martin Engineering utilize Class H windings and a rigid alloy frame to withstand maximum force output levels for longer sustained periods.
Designed to replace current vibrators sold for these demanding applications, the units are engineered with external bolt patterns compatible with conventional form brackets, creating a secure fit that allows the concrete to settle quickly for even distribution without air pockets. The result is greater reliability and service life, for a lower overall cost of operation.
Housed in a totally enclosed, non-ventilated (TENV) case, the concrete form vibrators feature an electric rotary motor as large as 230-460 volts (3 phase / 60 Hz), running at 3,450 RPM and producing as much as 3,000 pounds (1360.7 kg) of force.
While other manufacturers typically specify that vibrators should not be operated continuously at maximum output, Martin vibrators are rated for continuous duty at any setting.
Higher weight vibrators set on permanent brackets are supplied with grade 5 mounting bolts and compression washers to ensure a secure fit.
Portable units engineered for projects that require the device to be swapped among multiple forms can weigh as little as 20 pounds (9 kg).
The electric 115V, single-phase/60 Hz motor can be run as fast as 9,000 rpm, delivering 1,600 pounds (725.7 kg) of force. An optional speed control knob allows operators to fine tune the vibrator for each specific application, with eccentrics adjustable from 0-100%.