Several common steel structures [splicing of components]

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I.

splicing of components I.

equal section tension and compression bar splicing 1.

Factory splicing ① tie rod: direct butt welding (Fig.

a) or splicing plate plus fillet weld (Fig.

b) can be used.

During direct butt welding, the weld quality must meet the first and second level quality standards, otherwise the splice plate and fillet weld shall be used.

② Compression bar: direct butt welding (Fig.

a) or splicing plate plus fillet weld (Fig.

b) can be used.

When using splice plates and fillet welds, the flange and web of the component shall have their own splice plates and welds to make the force transfer as direct and uniform as possible and avoid excessive stress concentration.

When determining the width of web splice plate, enough space shall be reserved for operating welding rod when welding longitudinal weld.

2.

Site splicing ① tie rod: splicing plate plus high-strength bolt (Fig.

C) or end plate plus high-strength bolt (Fig.

d) can be used.

② Compression bar: it can be welded (Fig.

E and F) or the contact surfaces of the upper and lower sections can be planed and tightened to directly bear pressure and transfer force (Fig.

g and H).

When welding, the upper section of components shall be beveled in the factory in advance, and the lower section (or upper and lower sections) shall be equipped with positioning parts (channel steel or angle steel) to ensure the correct position during welding.

The contact surfaces of the upper and lower sections shall be planed and tightened, and a small amount of welds and bolts shall be supplemented to prevent staggered movement.

The splicing of tension and compression bars should be calculated according to the principle of equal strength, that is, the splicing materials and connectors can transmit the maximum internal force of the disconnected section.

II Splicing of variable cross-section columns (omitted) III.

splicing of beams {different splicing construction conditions of beams are divided into workshops (factory) splicing and site splicing.

1.

Factory splicing.

1) the factory splicing positions of flange and web should be staggered to avoid weld concentration.

2) butt welds are generally used for the splicing welds of flange and web.

3) checking calculation is not required for welds that meet grade 1 and 2 weld quality inspection levels.

4) checking calculation is required for welds that meet grade 3 weld quality inspection levels When the weld strength is insufficient, oblique weld can be used.

When θ Meet TG θ ≤ 1.5, checking calculation is not necessary.

2.

Construction of site splicing 1) generally, the flange and web shall be disconnected at the same section for segmented transportation (Fig.

a).

In order to make the flange plate have a certain expansion space during welding and reduce the welding residual stress, a length of about 500mm can be reserved in the factory without welding.

2) in Fig.

B, the splicing positions of flange and web shall be staggered appropriately, It can avoid the concentration of welds on the same section, but it is difficult to transport.

3) For riveted beams and important or large welded beams under dynamic load, high-strength bolts are often used for site splicing.

Connection of primary and secondary beams I.

the secondary beam is a simply supported beam 1.

Overlapping structure: supporting stiffeners shall be set at the corresponding positions on the main beam to avoid excessive local pressure on the web of the main beam.

Features: simple structure, convenient installation of secondary beam, but the clearance occupied by the main and secondary beam system is large.

Calculation: generally, there is no calculation, and the bolt only plays the role of installation and fixation.

2.

Side connection: Structure: the secondary beam is connected to the side of the main beam, It can be directly connected to the stiffener of the main beam (Fig.

A and b) or to the short angle steel (Figure C).

Features: figure a: it is connected to the stiffener with bolts, which has simple structure and convenient installation, but one side of the upper flange and lower flange of the secondary beam must be cut off; figure B: it is connected by site welds, at this time, the bolts only play a role of temporary fixation, but the welding at the end of the web of the secondary beam is not convenient; figure C and D: it is necessary to use short angle steel to connect the bolt connection or installation weld of the main and secondary beams The upper flange shall be partially cut off.

Calculation: figures a and B: the welds or bolts required for connection shall be calculated according to the reaction force of the secondary beam.

Considering that it is not an ideal hinge, it is advisable to increase the reaction force of the secondary beam by 20 ~ 30%.

Figure C: when calculating bolt ①, the short angle steel can be regarded as an integral part of the secondary beam.

Therefore, bolt ① should bear the joint action of secondary beam support reaction force R and moment M = re, while bolt ② only bears the action of R.

Conversely, the short angle steel can also be regarded as an integral part of the main beam.

Then bolt ① only bears the reaction R, while bolt ② should bear the joint action of secondary beam support reaction R and moment M = re.

Figure D: the calculation method is similar to figure C.

That is, weld ① and weld ② also bear the joint action of R or R and M = re respectively.

2、 The secondary beam is a continuous beam.

1.

The overlap ， is the same as the previous overlap, except that the secondary beam passes continuously and is not disconnected from the main beam When the secondary beam needs to be spliced, the splicing position can be set at the place with small bending moment As long as bolts or welds are used to fix their mutual positions between the main and secondary beams.

2.

Side connection: Structure: in order to ensure the continuity of two span secondary beams at the main beam, connecting plates must be set at the upper and lower flanges.

Figure a: it is connected with high-strength bolts.

The web of the secondary beam is connected to the stiffener of the main beam.

The connecting plate of the lower flange is divided into two pieces and welded on both sides of the web of the main beam.

Figure B: it is connected by site installation welds.

The secondary beam is supported on the support of the main beam.

The upper flange of the secondary beam is provided with a connecting plate, while the connecting plate of the lower flange is Replaced by a supported flat plate.

Calculation: the reaction force of the support is transmitted from the support to the main beam, the negative bending moment at the end is borne by the upper and lower flanges, and the horizontal force decomposed by M is transmitted by the connection, cover plate and top plate, F=M/h (H secondary beam height) the section size and the connection calculation of weld bolts shall be f.

in order to avoid overhead welding, the connecting cover plate shall be narrower than the upper flange and the pull plate shall be wider than the lower flange.

When the connection between beam and column is processed, the following basic principles shall be followed: safe and reliable.

The stress analysis shall be close to the actual working condition as much as possible, and the calculation method consistent with or close to the actual connection condition of components shall be adopted Calculation diagram; The connection shall have clear force transmission route and reliable structural guarantee.

Easy to manufacture, transport and install..