What are Construction Precautions for MSS660 Movable Scaffolding System?
Movable scaffolding system
1 Walkway for steel box girder of formwork at two sides is reinforced concrete walkway which not only bears load from workers, but also work as weights, 22t at each side, counterweights are set uniformly along 36m steel box girder
2 firstly fasten high tension bolts 8.8 grade at flanges, then tightly wedge with steel plates the part near to edges around triangular support and piers noted as K in the drawing, and tightly wedge with steel plates the part between pier and bottom part of concrete girder to avoid sliding for support and pier after receiving a stress. Stuff preformed hole with steel plates at left and right side between A, B brackets of support beam and pier stud, keep a firm contact between bottom part of support beam and holes in the pier, stuff with steel plate or level with cement mortar for preformed hole if necessary.
3 as installing three sets support frames, relative height difference between any one support frame and the other two support frames should be not more than 1cm, which should be controlled strictly in the worksite
4 as installing the formwork, adjust cross slope of top surface mainly by outer template, support frame installation must be in strict accordance with position marked in the drawing to avoid not enough distance for jacks
5 to avoid faulting of slab ends for new and old concrete caused by steel box girder deflection in the concrete girder cast-in-situ process and adding rear anchoring system, ZZHZ demands that 10t pre-stressing force shall be added for each pre-stressing high tension precision rolling thread bar reinforcement and stay casino online bar shall be adjusted to realize close contact between template and original concrete surface;
6 protection measures should be taken for safety in the using process for precision rolling deformed steel bar. To avoid accidents such as sparks striking in the electrical welding, electricity connection, local damage, then brittle failure caused by stress may be prevented. Put up and down gently in the construction. Frequent check and immediate replacement is necessary if the damage is found
7 to adapt the transformation from concrete box girder longitudinal slope to lateral slope, top surface of jacking jack is designed as arc. After completing formwork connection, adjust longitudinal and lateral slope of the formwork, start 4 sets jacks for jacking box girder. Jacking force of 2 sets jacks at each support point should be uniform to the greatest extent.
8 as installing formwork to the right position, firstly move laterally to close formwork, then adjust elevation by jacking, and then lock it tightly with mechanical lock and Harvard safety clip to realize safe guarantee. If plan metric position of formwork changes in the jacking process, re-adjust to make it horizontal by longitudinal and lateral moving jacks
9 adjustments for top surface elevation of formwork should take below factors into consideration:
Main girder elastic deformation after pouring the concrete;
Elastic and un-elastic compression deformation;
The influence that pre-stress tension on concrete box girder line
Pre-camber of finished bridge
10 as pushing longitudinally MSS660 system, take one set jack as pushing jack, the other as safety jack in the position transformation, safety stay bar must be added to avoid sliding down of MSS660. As concreting concrete, front and rear longitudinal moving jacks shall be fixed with steel box girder to prevent sliding down
11 It shall be completed as soon as possible for MSS movable scaffolding system lateral displacement and longitudinal crossing piers in the working condition with wind force < 5 grade. During the working process, pay attention to deformation conditions of support frame and guide beam and joints part between main girder and them, immediately handle the problem if it is found. Pay more attention to connection part between main girder and cross girder, joints between guide beam and main girder after crossing piers every time, check whether there is a deformation or damage or loosening bolts
12 thickening part is set at flange of expansion joint, to make the template more commonly-used, template at expansion joints can be used when two ends of construction parts have expansion joints, as for the rest girder section, fill with bamboo glue template and make it flat, stuff surface of template with quick dry putty or ash to ensure smooth surface and avoid mortar leakage
13 when the wind force is > 5 grade, moving and crossing piers should be forbidden, and wind force forecasting and field monitoring should be strengthen in the construction.
