Guangzhou Steel specify the contents of the convergence of high strength bolts
1, anti-slip coefficient is one of the main planning parameters of convergence of high strength bolts, directly affect the bearing capacity member, and therefore member friction surface treatment regardless of the manufacturer, or by the on-site treatment should be tested against the slip coefficient measured anti-slip coefficient planning requirements of this section shall comply with the minimum mandatory provision.
In the field portion of the device chosen grinding wheel friction surface, grinding range of not less than four times the bolt aperture, grinding direction should be perpendicular to the direction of the force member.
In addition to planning the choice of friction coefficient is less than equal to 0.3, and clearly may not be anti-slip coefficient test persons, the rest of the production situation in order to determine the processing method of the friction surface, you must press the required quantities and by three sets of the same material, the same processing method The specimen retest. At the same time along with three sets of the same material, the same specimen processing method for the device before the reinspection.
2, high strength bolts final tighten 1h, missing bolt pretension has been largely concluded, in the next one or two days, losing stabilized, after more than a month, the loss will stop, but in the external environment, bolts torque coefficient will change, affecting the accuracy of the inspection outcome. In order to unify and ease of operation, this provision must end at the same time checking within 1h after 48h.
3, the structure of this section refers to the planning reason reason causing space is too small to use a dedicated end wrench tighten conditions in torsional shear type high strength bolts of construction, because device sequentially, means the direction of ill-considered, or twist at the end because of the electric wrench to grasp the unskilled. Resulting in a final twist when the tail end of the ridge head Plum slip teeth (ie slip), you can not twist off the plum head, resulting in a final twist torque is unknown. Should be controlled to a certain percentage of these bolts.
4, the beginning of high strength bolts screwed screwed for the purpose of re-friction surface energy of tight and uniform bolt stress, focusing on large node node device order to prevent the loss of pre-tension bolts uneven impact of the convergence of stiffness.
5, forced penetration will damage the threaded bolt, changing the convergence deputy high strength bolts torque coefficient, and even the nuts are not screwed on, so focus on the freedom to penetrate bolt holes, gas cutting reaming very rules, both impair effective member carrying surface, reducing the pressure force transmission area, but also to cause defects reaming at the steel, it shall not gas cutting reaming, reaming maximum limits on the amount is based on the effective load transfer surface member and the friction force area of consideration.
6, for bolt-node grid, its stiffness (deflection) are often weaker than planned value, an important reason is because the ball and the steel bolt tightening is not strong convergence of high-strength bolts, a gap, loosening not tightened conditions, the current portion After removal of the support system, due to the convergence gap, loose and other reasons, deflection significantly increased, exceeding specification limits. Guangzhou Steel
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