How to select the three connection modes of reinforcement?

Whether the correct selection of reinforcement connection mode is directly related to the quality of the project. Several common reinforcement connection modes are analyzed and compared in combination with specifications and standards, so as to facilitate the correct selection of engineering design and construction personnel in the future.

 

Binding and lapping

1. Applicable and inapplicable scope

In “8.4.2 connection of reinforcement” in the national standard gb50010-2010 code for design of concrete structures, “8.4.2 longitudinal stressed reinforcement of axial tension and small eccentric tension rod shall not be bound and overlapped; when the reinforcement in other members is bound and overlapped, the diameter of tensile reinforcement shall not be greater than 25mm and the diameter of compression reinforcement shall not be greater than 28mm”.

The scope of inapplicability of steel bar binding lap joint is: “8.4.9 for components requiring fatigue checking calculation, the longitudinal tensile steel bar shall not use binding lap joint”; Longitudinal stressed reinforcement of axial tension and small eccentric tension rod; Tensile reinforcement with diameter more than 25mm and compression reinforcement with diameter more than 28mm shall not be used.

2. Advantages

General reinforcement workers can operate under any environmental conditions without additional processing, installation and testing equipment. The construction speed is fast and the quality is fully guaranteed.

3. Shortcomings and deficiencies

1) Double the joint reinforcement in the overlapping area, too much reinforcement occupies the cross-sectional area, the reinforcement at the member node cannot be placed, and the concrete shall not be poured and vibrated;

2) Most steel is used;

3) The force transmission performance is the worst.

 

Welded connection

There are five types of reinforcement welding connections: flash butt welding, arc welding, electroslag pressure welding, pneumatic welding and submerged arc pressure welding of embedded reinforcement, which shall meet the corresponding requirements of national standard gb50010-2010 code for design of concrete structures and industrial standard jgj18-2003 code for welding and acceptance of reinforcement.

 

1. Applicable and inapplicable scope

According to “8.4.9 of” 8.4 reinforcement connection “in gb50010-2010 code for design of concrete structures, the longitudinal tensile reinforcement of the member requiring fatigue checking calculation shall not adopt binding lap joint, welded joint, and no accessories shall be included on the reinforcement except for end anchorage”, it can be applicable except that the longitudinal tensile reinforcement of the member requiring fatigue checking calculation shall not be adopted; However, the welding of fine grain hot-rolled ribbed reinforcement and ribbed reinforcement with diameter greater than 28mm shall be determined by test, and the waste heat treatment reinforcement shall not be welded.

2. Advantages

Some welded joints are cheap and can be welded at any position within the allowable range of joints (if welding conditions are available).

3. Shortcomings and deficiencies

1) Special construction equipment, materials and electricity are required, with the largest energy consumption;

2) Strict requirements for personnel and certain requirements for the construction environment can not be used anytime and anywhere: for example, electroslag pressure welding can only be used for vertical reinforcement connection, flash butt welding and pneumatic welding can only be used to weld and connect limited length reinforcement in the processing yard;

3) The quality cannot be fully guaranteed, so it is easy to produce unqualified products and waste more.

 

connect

The mechanical connection of reinforcement includes straight thread, taper thread and sleeve extrusion, which shall meet the corresponding requirements of national standard gb500102010 code for design of concrete structures and industrial standard jgj107-2010 specification for welding and acceptance of reinforcement. It is rarely used now because of the backlog of sleeves and the unstable quality of conical thread connection and the force on the joint. The most commonly used straight thread joint is taken as the analysis and comparison object.

1. Applicable and inapplicable scope

All applicable without specifying the scope of unavailability.

2. Advantages

General reinforcement workers can operate under any environmental conditions, with the fastest construction speed, continuous and infinite extension, the best force transfer performance, super connection, stable and best quality.

3. Shortcomings and deficiencies

The cost is expensive.

 

cost analysis

1) The cost of binding connection is the cheapest, but it is actually only used in reinforcement with diameter no more than 14;

2) The construction cost of welded connection is in the middle, so “flash contact butt welding should be adopted for steel bar welded joints” in the industrial standard jtg1962.2004 code for design of highway reinforced concrete and prestressed concrete bridges and culverts and “flash butt welding should be preferred for steel bar welded joints” in the management and practice of Municipal Public Works (Third Edition);

3) The construction cost of straight thread joint is the most expensive, which is due to the high price of finished sleeve.

 

Conclusions and recommendations

1) Except for mechanical connection joints, various joints have their own scope of application, and attention shall be paid not to use beyond the scope;

2) Steel bar straight thread connection is the most expensive, but it is widely used because of its best quality and simple operation;

3) Although the price of welded connection is in the middle and recommended, the market share is gradually reduced due to high operation requirements, high energy consumption and incompletely controlled quality.

 

Source: Civil Engineering Paper Network Sohu No

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