In grid steel structures, steel columns are important vertical load-bearing components that bear the vertical load of the entire structure and transmit it to the foundation. Their quality and installation accuracy directly affect the stability and safety of the entire grid structure.

Steel columns can be divided into solid web columns and lattice columns according to their cross-sectional form. A solid belly column has an integral cross-section, with the most commonly used being an I-shaped cross-section, which performs well under relatively small loads and low requirements for column width; The cross-section of a lattice column is divided into two or more limbs, which are connected by strips or plates. When the load is large and the column body is wide, using lattice columns can save steel consumption. According to the stress situation, steel columns can usually be divided into axially compressed columns and eccentrically compressed columns. The longitudinal pressure exerted on an axially compressed column coincides with the centroid axis of the column's cross-section; Eccentrically compressed columns bear both axial pressure and bending moment, also known as compression bending members.



Preparation work is crucial before hoisting and installing steel columns. In terms of personnel, it is necessary to ensure that construction personnel have received professional training and are familiar with the steel column lifting process and safety precautions. On the equipment, conduct a comprehensive inspection and debugging of lifting equipment such as cranes to ensure their stable operation and good performance. At the same time, prepare auxiliary tools such as slings, lifting devices, theodolites, and level gauges. It is also necessary to conduct a detailed inspection of the steel columns to check for any deformation or damage to their appearance, whether their dimensions meet the design requirements, and whether the components are complete. In addition, the location and quantity of lifting points need to be determined based on the shape, cross-section, length, weight of the steel column, as well as the lifting performance of the crane. Generally, steel columns with good elasticity are often lifted at one point, with lifting ears placed at the top of the column to make the column vertical and facilitate alignment correction; If limited by the length of the crane arm, the lifting point can also be set at 1/3 of the column, but at this time, the steel column tilts and the difficulty of line correction increases; For long and thin steel columns, to prevent deformation, two-point or three-point lifting can be used.



During formal installation, the first step is to retest the foundation, reviewing the positioning axis, column foot elevation, and anchor bolt position to ensure that the foundation meets the installation requirements. Then the steel column is lifted, and common lifting methods include rotation, sliding, and delivery. The rotation method involves the crane lifting the hook while rotating, causing the column to rotate around the column base and lift the steel column. During lifting, a pad should be placed under the column base to avoid friction with the ground, while ensuring that the lifting point and column base foundation are on the arc of the crane boom rotation; Sliding method is a single or double machine lifting method, where the crane only lifts the hook to allow the steel column base to slide and lift the steel column. A taxiway needs to be laid between the steel column and the ground; The delivery method is generally two or three machine lifting, with one auxiliary machine selected as the lifting point under the steel column. When lifting, it cooperates with the main machine to deliver the steel column base to the steel column foundation, and then the auxiliary machine removes the hook. After the steel column is in place, the verticality, longitudinal and transverse displacement, and elevation of the steel column should be adjusted using a theodolite and a level, and the deviation should be controlled within the allowable range. After the adjustment is completed, firmly connect the steel column to the foundation through anchor bolts, and perform secondary grouting on the column base to enhance the stability of the connection.



During the hoisting and installation of steel columns, it is necessary to strictly follow the safety operating procedures, set up clear warning signs, and prevent unrelated personnel from entering the hoisting area; In case of adverse weather conditions such as strong winds, heavy rain, heavy fog, etc., lifting operations should be stopped; Regularly inspect and maintain lifting equipment and rigging to ensure their safety and reliability.