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Common sense of steel bar joint construction in construction engineering
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Common sense of steel bar joint construction in construction engineering
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1. Connector usage regulations
(1) For steel bars with a diameter greater than 12mm, Hufeng Machinery should preferably use welded joints or mechanically connected joints.
(2) When the diameter of the tension steel bar is greater than 28mm and the diameter of the compression steel bar is greater than 32mm, it is not suitable to use lap joints.
(3) Lap joints shall not be used for longitudinally stressed steel bars of axial tension and small eccentric tension members (such as trusses and arch tension rods).
(4) Among the structural members directly bearing dynamic loads, the longitudinal tensile reinforcement shall not be bound with lap joints.
2. Allowable percentage of joint area
In the same connection section, the percentage of the lap joint area of longitudinal reinforcement is the ratio of the cross-sectional area of longitudinally loaded steel bars with lap joints to the cross-sectional area of all longitudinally loaded steel bars in this section.
(1) The length of the connection section of the steel bar binding lap joint is 1.3, and all the lap joints whose midpoint is within the length of the connection section belong to the same connection section. In the same connection section, the percentage of lap joint area of the longitudinal tensile reinforcement of Hufeng Machinery shall meet the design requirements; when there is no specific requirement in the design, it shall meet the following regulations:
1) For beams, slabs and walls, it should not be greater than 25%;
2) For column members, it should not be greater than 50%;
3) When it is really necessary to increase the joint area percentage in the project, it should not be greater than 50% for beam members; for other members, it can be relaxed according to the actual situation.
The area percentage of lap joints of longitudinally compressed steel bars should not be greater than 50%.
(2) The length of the connection section between the mechanical connection of the steel bar and the welded joint is 35 times d (d is the larger diameter of the longitudinally stressed steel bar), and not less than 500mm. In the same connection section, the joint area percentage of the longitudinally stressed reinforcement shall meet the design requirements; when there is no specific requirement in the design, it shall meet the following regulations:
1) The tension area should not be greater than 50%; the compression area is not restricted;
2) The joints should not be arranged in the stirrup densification area at the frame beam end and column end with seismic fortification requirements; when it cannot be avoided, the equivalent strength and high quality mechanical connection joints should not exceed 50%;
3) Welded joints should not be used for structural members directly bearing dynamic loads; when mechanically connected joints are used, it should not exceed 50%.
3. Lashing splice lap length
(1) The lap length of the lap joints of the longitudinally tensioned steel bars should be calculated according to the area percentage of the lap joints of the steel bars in the same connection section according to the following formula:
ll=ξla (9-3)
In the formula, la—the anchorage length of the longitudinal tension reinforcement, ξ——the correction coefficient of the overlap length of the longitudinal tension reinforcement,
Correction factor according to the lap length of longitudinal tensile steel bars
| Lap joint area percentage of longitudinal reinforcement (%) |
≤25 |
50 |
100 |
|
ξ |
1.2 |
1.4 |
1.6 |
(2) When the longitudinal compression steel bars in the members are connected by lap joints, the compression lap length should not be less than 0.7 times the lap length of the longitudinal tension steel bars, and should not be less than 200mm in any case. (3) Within the overlapping length of longitudinally stressed steel bars of beams and columns, stirrups should be configured according to design requirements. When the design has no specific requirements, the following provisions shall be met: 1) The diameter of the stirrup should not be less than 0.25 times the larger diameter of the lapped steel bar; 2) The stirrup spacing in the tension lap section should not be greater than 5 times the smaller diameter of the lapped reinforcement, and should not be greater than 100mm; 3) The spacing of the stirrups in the compression overlapping section should not be greater than 10 times the smaller diameter of the overlapping reinforcement, and should not be greater than 200mm; 4) When the diameter of the longitudinally stressed reinforcement in the column is greater than 25mm, Hufeng Machinery shall set up two stirrups within 100mm of the two end faces of the lap joint, and the distance between them should be 50mm.
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