Installation of Steel Structure for Multilayer Workshop Building

The installation of steel structure components for multilayer workshop buildings involves the sequential hoisting, positioning, connection, adjustment, and fixing to their designed locations according to design and construction specifications. The steel structure of multilayer workshop buildings is designed based on the needs of the production process layout, with interconnected production equipment installed on multiple platforms and floors. In metallurgical plants, multilayer steel structures include sintering workshops, pulverized coal preparation workshops, and high-level material silos in smelting workshops.

 

 

Multilayer steel structure workshop buildings are characterized by their overall height, large span, multiple platform levels, complex component connection methods, and the interweaving of workshop and equipment installation. Before installing the steel structure, it is essential to carefully review the drawings, prepare a construction organization design, a general construction plan, and an installation engineering network plan, and conduct re-measurement and acceptance of the benchmark points of each platform and column foundations, as well as quality inspection of the steel structure components.

 

 

Generally, installation proceeds layer by layer from bottom to top, following the sequence of columns, crane beams, platforms, roof, and walls.

 

Column System Installation

 

The installation steps and methods are as follows:

(1) Install support components under the column base plate. Methods include: embedded iron component method (Figure a), reserved concrete pad method (Figure b), adjustable anchor plate support method (Figure c), steel pad method (Figure d), concrete grouting method (Figure e), and fluid grouting method.

(2) Column hoisting. Use the selected lifting equipment to hoist and position the column. When the lifting capacity is sufficient for the overall hoisting of the column, and the factory environment and other conditions permit, multiple column sections should be spliced ​​together on-site for overall hoisting; when the column cannot be hoisted as a whole, a bottom-up, section-by-section installation method with aerial joints should be adopted.

(3) Column adjustment. After the column is hoisted and positioned, adjustments should be made according to the requirements of the construction acceptance specifications: first, align the column centerline with the foundation coordinate line, and adjust the column elevation to the design height; then, straighten the column. Ensure the column's elevation, centerline, parallelism, and plumbness all meet the installation accuracy specified in the standards. After adjustment, fix the column and perform secondary grouting. For multi-section columns, a method of simultaneous installation and adjustment should be adopted.

 

Crane Beam System Installation

 

Proceed as follows:

(1) Re-measurement of crane beam geometry.

(2) Lifting the crane beam into position using lifting equipment.

(3) Adjustment and fixing of the crane beam. The method is as follows: Use a theodolite and steel ruler to measure and mark the installation centerline of two rows of crane beams in the same span, and check the span between the centerlines; straighten, align, and level the crane beam; after verifying that the straightness, span, and elevation of the crane beam centerline meet the standard requirements, fix the crane beam;

(4) Installation of the braking system. The crane beam braking system generally consists of a braking truss (braking beam), upper and lower chord braking supports, and vertical supports. For ease of movement, a walkway is laid on top of the upper chord braking support. Some cranes do not have an upper chord brake support, but instead have a brake plate that serves both as a brake and a walking surface. The installation method is as follows: first, lift the brake truss (or brake beam) into position, straighten, align, level, and fix it; then install the upper and lower chords, vertical supports, and walkway plates (or brake plates).

(5) Crane rail installation. The method and sequence are: use a theodolite and steel ruler to mark the positioning axis of the rail on the crane beam, and measure the span between the positioning axes of two rails in the same span; check the deviation between the positioning axis and the center line of the crane beam, and mark it if it meets the specifications; according to the rail layout drawing, lift, align, and straighten the rail; connect the rails with rail connectors, and fix the rails to the crane beam with fasteners. There are two methods for connecting rails: clamp bolt connection and welding. When welding, the bevel should be prepared according to regulations, welding molds should be made, and attention should be paid to preheating before welding and heat treatment after welding. The outermost weld should be covered with wear-resistant welding rods. After welding, grind the weld seam smooth with a grinding wheel.

 

Platform Structure Installation

 

This should be carried out after the column system installation and before the roof structure installation, proceeding layer by layer from bottom to top. When installing each platform layer, the main beams should be installed first, followed by the secondary beams, with simultaneous installation, adjustment, and fixing.

 

Roof System Installation

 

The sequence and method are as follows:

Installation of the bracket beams;

(2) Installation of the roof trusses. If the roof trusses are shipped in sections, an assembly platform should first be erected on the ground to assemble the trusses into a whole, and then hoist them into place;

Installation of the roof beams, supports, and purlins;

Installation of the roof ventilation ducts. There are two methods: one is single-piece high-altitude installation, and the other is to assemble the ventilation ducts in sections on the ground and then hoist them into place as a whole. Throughout the entire roof system installation, the method of simultaneous installation, adjustment, and fixing must be adopted.

 

Wall System Installation

 

The wall structure includes columns, wind-resistant trusses, wall purlins, etc. The installation sequence is: (1) wall columns, wind-resistant columns; (2) wind-resistant trusses; (3) wall purlins. There are two installation methods: one is to hoist individual pieces according to the above sequence, and the other is to assemble the wall columns and purlins into sections on the ground when conditions permit, and then hoist them into sections. The method of simultaneous installation, adjustment, and fixing must be adopted during construction.

 

Component Connection Methods

 

There are two types of connections: welding and high-strength bolt connections.

• Welding Connection

Because component connections are mostly high-altitude operations, with a large workload and strict quality requirements, it is stipulated that welders must hold a qualification certificate before welding; welders must carefully select, store, bake, and use welding rods (wires) according to specifications and design requirements. The steel grade and welding materials used for the first time must undergo welding process performance and mechanical performance tests, and can only be used after meeting the requirements; the bevel type of the weldment must meet the specifications and be suitable for on-site welding; the welding process and inspection must be strictly followed during the welding process to ensure the quality and appearance of the weld.

• High-strength bolt connection

There are two types of high-strength bolts: large hexagonal and torque-shear type.

The construction methods for large hexagonal high-strength bolts are torque method and angle method.

The torque method is simple, accurate and practical, that is, using an electric or manual torque wrench, setting the construction torque of the bolt, and performing initial tightening and final tightening one by one. For torque-shear type high-strength bolts, the initial tightening is done with a torque wrench, and the final tightening is done with a special final tightening wrench.

The construction procedure for high-strength bolts is:

(1) Check the manufacturer's high-strength bolt friction surface test report to check whether the anti-slip coefficient meets the design and specification requirements. And verify according to the test pieces provided by the manufacturer.

(2) Treat the friction surfaces of the component connection parts and connecting plates to make them flat, free from rust and oil stains. The friction surface should maintain the specified roughness and should not be smooth.

(3) When connecting, ordinary bolts should be used for temporary fixing first. The number of ordinary bolts used should generally be more than 1/3 of the total number of holes in the node.

(4) After the component is adjusted and the temporary bolts are tightened, high-strength bolts should be inserted (replaced) one by one. (5) Use an initial tightening wrench to tighten the bolts one by one from the inside out, and then use a final tightening wrench to tighten them in the same order (the initial tightening torque is generally 60% to 80% of the final tightening torque).

(6) Seal the perimeter of the connecting plate with putty or a thicker paint.

(7) Apply oil to the outer surface of the connecting plate.

 

Component Coating

 

Special attention should be paid to the coating quality during installation:

The surface of the component should be sandblasted or shot blasted to remove rust and rolled iron oxide layers;

The type and color code of the paint should be determined according to the design requirements;

The dry film thickness of the paint should be determined according to the design requirements. If there are no design requirements, the thickness should generally be controlled at 100-125μm for indoor components and 125-150μm for outdoor components;

Coating should be carried out strictly according to the coating specifications and processes;

The construction method of painting the components in the factory or on site and then hoisting them can be adopted. In order not to damage the topcoat on the surface of the component, flexible slings must be used to tie the component during hoisting. Alternatively, a topcoat can be left before installation and then painted at high altitude after installation.