Reinforcement methods for large rooftop billboards

1. The control design load of the billboard structure is wind load. The wind pre ssure acts directly on the panel, and then is transmitted from the panel to the frame. At this time, several main beams at different elevations The wind load can be transmitted to the columns evenly, so the stress concentration at the connection between the main beam and the column can be reduced;

2. The main beam of the parallel truss structure uses channel steel to make the structure flat. It facilitates the attachment of advertising panels and can strengthen the connection between the panels and the main frame, thereby reducing the deformation of the panels to ensure the sensory effect of the advertising surface;

3. Parallel truss layout, which can be used in each lane Main beam elevation is set within the maintenance ladder. This brings great convenience to the protection, maintenance, hanging and unloading of advertising banners, and ensures the personal safety of operators;

4. In addition, the parallel truss layout, Simple, beautiful, clear stress, simple node structure, convenient construction, thus ensuring construction quality;

5. Structural installation This project uses independent steel structural columns, which are constructed at three different elevations through node plates. Three transverse main beams are welded, and transverse beams and diagonal supports are set between the main beams to form a space truss stress system;

6. The distance between the main and cross beams mainly considers the placement of the advertising panel skeleton grid. And make the panel skeleton nodes consistent with the main skeleton nodes to strengthen the connection between the panel and the main skeleton. The frame of the billboard panel itself is hung and welded on the main structure to form the overall upper structure.

The main beam is made of channel steel, and other components are made of angle steel. The type is selected according to the strength and deformation conditions of the components;

7. When selecting the steel column section, in addition to considering its strength and stability, factors such as the overall scale, harmony and beauty of the billboard must also be considered.

1. Foundation expansion method: By setting up concrete enclosures or reinforced concrete enclosures, increase the area of ​​the bottom foundation of outdoor LED billboards, and change the problems caused by the small bottom area and insufficient bearing capacity of the billboard foundation. Uneven settlement of foundation.
2. Pit underpinning method: dig a pit directly under the foundation to be underpinned and then pour concrete.
3. Pile underpinning method: The method of setting up static pre ssure columns, driven piles, cast-in-place piles and other types of piles at the lower part or both sides of the billboard foundation for foundation reinforcement.
4. Grouting underpinning method: Inject chemical slurry evenly into the foundation, and use this slurry to cement and solidify the original loose soil or cracks, so as to improve the bearing capacity of the foundation and achieve waterproofing and anti-seepage effects.

At pre sent, the main methods of reinforcing the foundation of outdoor billboards are as follows:
(1) Foundation expansion method: by setting up concrete enclosures sets or reinforced concrete enclosures to increase the area of ​​the bottom foundation of the billboard and change the uneven settlement of the foundation caused by the small bottom area and insufficient bearing capacity of the billboard foundation.
(2) Pit underpinning method: Dig a pit directly under the foundation to be underpinned and then pour concrete.
(3) Pile underpinning method: The method of setting up static pre ssure columns, driven piles, cast-in-place piles and other types of piles at the lower part or both sides of the billboard foundation for foundation reinforcement.
(4) Grouting underpinning method: Inject chemical slurry evenly into the foundation, and use this slurry to cement and solidify the original loose soil or cracks, so as to improve the bearing capacity of the foundation and achieve waterproofing and anti-seepage effects.
Correction is to use artificial means to reversely tilt the tilted foundation to achieve the purpose of correcting the tilt of outdoor billboards. Commonly used methods for correcting the foundation of outdoor billboards include the following:
(1) Forced landing correction method: Take measures to pre vent sinking on the side of the outdoor billboard where the foundation has settled more, and take forced landing measures on the other side. . Crash landing methods include: loading steel ingots or stones, building cantilever beams, digging out soil for forced landing, water injection to correct deviations, etc.
(2) Jacking correction method: In the parts of the tilted billboard where the foundation settlement is large, adjust the lifting amount of each part of the billboard to make it rotate in an overall plane along a certain point or a certain straight line to achieve recovery. purpose in situ.
Maintenance and reinforcement of steel structures
Since the strength of steel is higher than other common engineering materials, the main support structure of outdoor billboards is usually made of steel materials. In the open air environment, steel materials are easily oxidized and corroded due to the influence of temperature, humidity, harmful substances and other factors. Severe corrosion can greatly reduce the load-resisting ability of steel components; steel materials have good Toughness, but under long-term load or low temperature, steel materials are also prone to embrittlement and fracture; in addition, during the design and construction process of outdoor billboards, there are defects in local or even overall stability; or during use, maintenance, and modification During the process, loose bolts, overloading, external impact, etc. may cause overall imbalance; in addition, using inferior steel to construct the main structure of the outdoor billboard; and welding other steel plates on the billboard without considering its load capacity will cause serious consequences.
The following points should be noted in the daily maintenance of steel structures:
Strict selection of materials. When selecting steel materials, the chemical composition and mechanical properties of the steel materials used in the steel structure should be tested, and the appearance of the steel materials should be inspected. Materials with defects such as cracks, rust spots, and scars should be discarded.
Construct with caution. During the construction process of billboards, damage to the appearance of the steel used should be avoided, and drilling and welding of key stress-bearing parts are prohibited.
Regular testing. After the billboard is put into use, its safety should be checked regularly, and damaged and aging components should be discovered and replaced in a timely manner. If the main components are seriously aged or damaged, reinforcement measures should be considered.
Pay attention to anti-corrosion. The most commonly used anti-corrosion measures for steel include: painting the surface of the steel, or spraying a metal protective layer on the surface of the component; contact between different metals can also cause corrosion. If different metal materials are used in the construction, the contact surfaces should be insulated; In addition, when designing, attention should also be paid to the placement of materials to avoid water accumulation caused by the grooves of the steel facing upward, which may cause corrosion of the material.
When the outdoor billboard steel structure has design flaws or is damaged by external forces, which affects its solidity, it should be reinforced in time. There are many methods to strengthen steel structures. In summary, they mainly include the following:
Increase the stress section. This method is widely used to reinforce billboard supports and node steel plates. It can improve the bearing capacity of the components, but it will also increase the weight and cost of the billboard itself, which has limitations in use.
Additional pre stressed tie rods or braces. This method can improve the bearing capacity of the component and increase its crack resistance. Since this method changes the stress distribution of the original overall structure, detailed mechanical calculations should be done during implementation.
Add a fulcrum or bracket. This method can reduce the load-bearing span of components, reduce the mechanical load inside the steel structure, and slow down the aging and deformation of materials. Mostly suitable for the expansion of billboards.
Added fulcrum. The stability and safety factor of the overall structure of the billboard can be enhanced by increasing the number of support base plates and chemical expansion bolts or planting steel bars.
Grouting method to repair cracks. Use pre ssure-feeding equipment to pour chemical slurry into structural cracks to repair them. The poured chemical slurry can repair cracks in the concrete, pre vent rust and strengthen it, and improve the overall durability of the component. It is usually used in the reinforcement between the billboard foundation and the connecting steel plate.
Adhesive reinforcement method. This is a reinforcement method that sticks steel plates to the outside of the component. It has the advantages of easy operation, short construction period, small space occupation, and almost no change in component appearance. Usually used for load-bearing reinforcement of building billboard supports.