Steel Structure Operation Process (3)

E. Hole making

a. Components using high-strength bolts (large hexagonal head bolts, torsion shear bolts, etc.) ﹑ half-round head rivets tapping screws and other hole production methods are: drilling, milling, punching, reaming or countersinking, etc..
b. Component hole production priority drilling, when the proof of certain material quality, thickness and aperture, punching will not cause brittleness when allowed to use punching.
The thickness of all ordinary structural steel below 5mm allows punching, secondary structure thickness less than 12mm allows the use of punching. On the punched hole, no subsequent welding (slotted) shall be applied, unless it is proved that the material retains considerable toughness after punching, then welding construction is allowed. Generally in the need for the hole punched and then drilled largely, then the punched hole must be smaller than the specified diameter of 3mm.
c. Before drilling, one is to sharpen the drill bit, and the other is to choose the chip margin reasonably.
d. The bolt hole made should be cylindrical and perpendicular to the surface of the steel at the location, and the inclination should be less than 1/20, and the perimeter of the hole should be free of burrs, breaks, flares or bumpy marks, and the cut should be clean.
e. Refined or reamed bolt hole diameter and the diameter of the bolt rod is equal, with drilling or reaming after assembly, the hole should have the accuracy of H12, hole wall surface roughness Ra ≤ 12.5μm

F. Friction surface processing

a. High-strength bolts connected to the friction surface processing can use sandblasting, shot blasting and grinding wheel machine grinding methods. (Note: grinding wheel machine grinding direction should be perpendicular to the force direction of the member, and the grinding range shall not be less than 4 times the diameter of the bolt.)
b. The treated friction surface should take anti-oil and damage protection measures.
c. The manufacturing plant and the installation unit shall conduct the anti-slip coefficient test with the steel manufacturing batch respectively. Manufacturing batch can be divided into divisions (sub-part) of the project provisions of the volume of work every 2000t for a batch, less than 2000t can be regarded as a batch. When two or more surface treatment processes are selected, each treatment process should be tested separately, each batch of three groups of test pieces.
d. Slip resistance test specimens should be processed by the manufacturer, the specimens and the representative steel members should be the same material, made in the same batch, using the same friction surface treatment process and have the same surface state, and apply the same batch of high-strength bolts with the same performance level, stored in the same environmental conditions.
e. The thickness of the test piece steel plate should be determined according to the thickness of the representative plate in the steel structure project. The surface of the specimen plate should be flat, free of oil and grease, and the edges of the holes and plates should be free of flying edges and burrs.
f. The manufacturer shall conduct the test of slip resistance coefficient at the same time as steel structure manufacturing and issue a report. The test report shall state the test method and results.
g. According to the current national standard "Design, Construction and Acceptance of High Strength Bolted Steel Structures" JGJ82 or the design documents, the same material and treatment method should be used to make the components for review of the slip resistance coefficient, and handed over at the same time with the components.