Prestressing process and problems to be paid attention to in the construction of prestressed section steel composite support:
1The order of applying prestress after the arrangement of each member of the tool type combination inner support is as follows
(1(Check whether the connection of bolts of each part is tight, and the connection status of enclosing purlin and enclosing system. In the pre-prestressing phase, the enclosing purlin is applied first for a better connection with the surrounding retaining wall20TThe prestress of.
(2) Angle brace pressure.
(3(The steel strand is stretched.
2, some problems should be paid attention to in the process of applying prestress:
(1) Before tensioning, the tensioner, oil cylinder, oil gauge and other equipment should be calibrated.
(2) With the application of the newly installed bracing stress, the stress of the adjacent already installed bracing may decrease, so the prestress can be added according to the design requirements. Therefore, the support must have a prestressed device (that is, the support connector). When the horizontal displacement rate of the wall exceeds the warning value, the prestress can be increased to control the deformation.
(3) When applying prestress, check the connection of each contact in time and make a record of applying prestress; It is strictly prohibited to support in the application of prestress due to the embedded parts can not even contact and lead to eccentric compression; After the support force is exerted, it is necessary to strictly check and eliminate the gradual change due to the non-vertical support and compression surface, which leads to the continuous increase of the horizontal displacement of the retaining wall of the foundation pit and even the instability of the support.
(4) in order to control the length of the jack cylinder extended in10cmWithin, the cylinder length can be adjusted by setting a steel plate behind the jack when pressurizing.
(5) The compression of the support shall be carried out strictly according to the axial force provided in the design drawing, and improper loading or overloading is not allowed.
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