Logistics Warehouse Steel Structure Node Connection Method

With the rapid development of the social economy, the city construction of our country is speeding up, the steel structure industry develops rapidly, and all types of steel structure buildings constantly appear around us, mainly benefit from steel structure has light weight, high strength, superior seismic performance, short construction cycle and low cost of good performance. Wuhan Huoshenshan Hospital only takes about 10 days from construction to delivery, which highlights the advantages of high construction efficiency and short construction period of steel structure buildings. At present, the production and construction quality management system of steel structures is gradually improving, and the quality is getting better and better. Due to the short construction period and the relatively low construction cost for long-span buildings, it is widely used in the construction of logistics parks. The steel structure connection node, as the focus of the quality control of the steel structure, will determine the success or failure of the overall construction of the warehouse. This paper will take a logistics park project as an example to discuss the connection way of steel beam-columns of a warehouse structure.

1. Portal frame node connection mode

In the logistics warehouse steel structure foundation and column foot, steel column and steel beam, steel beam and steel beam, and other main structure connections, can be used in the field of manual welding, factory welding, and high-strength bolt connection, its main advantages and disadvantages are shown in the table below

The selection of the steel structure connection node scheme of the logistics warehouse is based on the difficulty of site installation, quality control of the connection node, economic benefits, construction period, safety, and other aspects combined with the characteristics and requirements of the warehouse, after comprehensive consideration.

2. Select an example

Warehouse steel structure project of an Industrial logistics warehouse: a total construction area of 24800 square meters, warehouse building area of 6,156 square meters. Warehouse gable side length is 108 meters, depth is 57 meters, column distance is 9 meters, warehouse span is 26+26+5 meters, cornice height is 11.9 meters, Class C buildings, fire resistance grade is two, seismic fortification intensity is 6 degrees. The structure is a single-layer gantry rigid frame structure without a crane, the gantry column is a wedge-shaped variable section H steel column, and the gantry beam is a wedge-shaped variable section H steel beam. The design life of the main structure is 50 years. Through the case analysis of steel structure column foot and foundation connection nodes, beam, and column connection nodes, beam and beam connection nodes, and other parts of the connection scheme selection, the logistics warehouse steel structure node connection mode selection is discussed.

2.1 Connection scheme of column foot and foundation

The joint of the column foot and the foundation is an important part of connecting the steel structure and foundation, which plays a connecting role and has a great influence on the safety and cost of the whole structure. Column foot forms can be divided into exposed column foot, embedded column foot, and outsourcing column foot.

1)Exposed column foot. Are the steel structure of the steel column through the bottom plate and anchor bolt fixed on the concrete surface of the column foot, including the bottom plate, stiffener, and anchor bolt, and anchor bolt support bracket, each part has its different functions. This kind of column foot design theory is more mature and widely used, is the most common column foot node in the gantry rigid frame structure engineering practice, with a simple structure, convenient positioning, and simple construction, and its effect is very obvious, especially in the column foot hinged steel structure building has a very wide range of applications. The disadvantage is that the size of the rigid column foot is large, there are certain difficulties in processing, and the construction will produce certain errors.

2)Embedded column foot. The steel column is buried on the independent foundation of reinforced concrete, and the bending moment of the column foot is transmitted to the foundation by inserting the connection between the steel structure and the concrete. It can only be used for the rigid column foot. Its advantages are good seismic performance, a high degree of rigid connection, in high-rise steel structure building more applications, disadvantages are complex structure, long construction period, and high construction cost.

3)outsourced pillar foot. It is a reinforced concrete column foot outside the steel column foot. The basic structure is that the bottom plate of the steel column is flush with the outsourcing concrete, and the outsourcing part of the steel column is provided with a bolt. Its structure is simple, does not affect the foundation reinforcement layout, is used for rigid column feet, if used as hinged column feet, the cost and construction difficulty, and cycle are higher than exposed column feet.

4)Analysis, comparison, and selection. Because the logistics project steel structure warehouse for no crane door type single rigid frame light steel structure, seismic for proof intensity is 6 degrees, through the analysis and comparison of the above three kinds of column foot form construction technology and its advantages and disadvantages, from the construction period, cost, quality, safety and other angles of comprehensive comparison, can be used hinged column foot or rigid column foot, Because the hinged column foot in the construction cost, construction period and construction difficulty are lower than rigid column foot connection, so the project uses hinged column foot; And in the hinged column foot can be divided into exposed column foot, outsourcing column foot two kinds of connection, exposed column foot from the construction cost, construction difficulty, construction cycle point of view, are better than outsourcing column foot, so choose exposed hinged column foot connection scheme.

2.2 Connection scheme of the main structure of steel structure.

The main structure connection nodes are beam and column, beam and beam, and other nodes of steel structure, which is the core of steel structure quality control. If the nodes are destroyed, it will inevitably destroy the overall steel structure system of the logistics building and cause major safety accidents. Therefore, the design scheme selection of the steel structure’s main component connection nodes is the top priority in the design of the steel structures. This project is a gantry rigid frame logistics warehouse with a large warehouse area, high column height, and more rigid frames so that there are more on-site connection nodes, greater construction difficulty, greater workload, poor construction site environment, and simple construction equipment. According to the characteristics of this project, the main structure of steel structure can be connected in three forms: factory welding, field welding, and high-strength bolt connection.

1) Factory welding: high degree of automation, fast welding speed, low labor intensity, good weld quality, but high requirements for equipment and environment. Factory welding is taken in the steel structure manufacturing workshop and then transported to the site. In this project, the single rigid frame of the door steel structure is 57 meters long and 11.9 meters high, with a large overall body. Generally, the road width and turning radius cannot meet the transportation conditions, and the general vehicle size cannot meet the transportation requirements of rigid frame or the height of the wood. Therefore, the factory welding scheme is not adopted. However, since the factory welding quality is the best and the cost is the lowest, the beam and column components of this project are welded by the factory to ensure their structural quality and then transported to the construction site in sections.

2) On-site welding: On-site welding has certain advantages in non-standard welding parts, less welding amount and more specifications, but it has higher requirements for welder skills and working environment. In the process of on-site welding, when the position to be welded is relatively hidden, the welding operation space is too small, and the area to be welded cannot be seen directly by the eye, resulting in abnormal welding work, increasing the difficulty of welding, and affecting the welding quality. In addition, an ultrasonic inspection of the weld also increases the difficulty: on-site welding operations should do a good job of the head, face, eye, respiratory tract, and hand and other personal protection, in the height of the working time more to do a good job of safety protection against falling. For example, the connection between beam and column, beam and beam adopts the method of field welding, the workload is large, and the field welding beam and column belongs to the high altitude operation, relative to the high strength bolt connection, increase the risk factors, there is a certain quality hidden trouble; Manual welding joint labor intensity, low production efficiency, in recent years, with the increase of labor wages, the cost of manual welding increased significantly, steel structure construction under the condition of permitting should try to avoid on-site welding, the main structure of the project did not adopt on-site welding joints; However, the partial use of on-site welding on the attached structure is mainly due to the small welding amount of the attached structure, more non-standard parts and less high-altitude operation, which has little impact on the safety of the main structure.

3) High strength bolt connection: simple construction process, convenient installation, high production efficiency, high standardization, controllable quality, especially suitable for logistics project site installation connection, bolt connection fatigue resistance is stronger than welding connection. Due to the characteristics of large construction volume, high altitude operation, and poor site environment of the main structure of the project, high-strength bolt connection can avoid weld quality defects caused by on-site high altitude welding, and reduce the ultrasonic inspection link required by on-site welding. Compared with the welding method, the construction quantity can be reduced. Under the condition of a poor site environment, Because of the high strength bolt connection mode, the standardized construction degree is higher, the construction process is simple, the single node workload is less than welding, the quality is more controllable, and the construction safety risk is less when working at altitude. With the increase of labor wages in recent years, the labor cost of on-site welding has increased substantially, coupled with the continuous improvement of production and manufacturing level of steel structure manufacturers in various logistics warehouses, the adoption of high-strength bolt connection has high installation efficiency, and the cost is reduced relative to on-site welding connection, so it has more advantages than manual welding. Therefore, the main structure of the project adopts a high-strength bolt connection node.

Based on the above analysis, according to the characteristics of the warehouse steel structure, it is the most favorable to the quality, safety, schedule, and cost of the warehouse to choose the factory welding of the main structural components, high-strength bolted connection of the main structural joints and on-site welding of the auxiliary structures.

Aiming at the node design of the gantry rigid frame structure system of the steel structure building of the logistics warehouse without a crane and combining the comprehensive consideration of quality, safety, schedule, cost control and other aspects, The connection scheme of exposed articulated column feet, the main structural members choose factory welding, the main structure node connection method using high strength bolt connection, the auxiliary structure using the site welding node connection method is the best scheme, can ensure the quality and safety of the premise, improve the project progress, save the cost.