What is a lattice column? Key points of lattice column construction
Lattice columns are generally section steel or steel plates designed to be biaxially symmetrical or uniaxially symmetrical. The steel beam and the steel column are connected by a strong shaft. To avoid lateral deformation of the steel beam hoisting, reinforcement measures are adopted during hoisting. When the steel beam is in place, it is immediately connected for support. After the roof panel is installed, no welding is allowed on any part of the roof truss.
Function: The lattice column is used as a bending member in the column, which is mostly used for the frame column of the factory building and the independent column. The section is generally designed as a biaxially symmetrical or uniaxially symmetrical section of section steel or steel plate. The components of the lattice system are composed of limbs and braces. The limbs mainly bear axial force, and the braces mainly resist lateral force (relative to the axial direction of the limb).
Lattice column decoration materials mainly include strips and panels.
That is, at the enlarged ends on both sides of the foundation pit, the length of the first concrete support and the second and third steel supports are longer, which generates bending moments and causes the support to deform. Therefore, lattice columns are set to improve the bending resistance of the support members. , To ensure the stability of the supporting structure.
The structural characteristics of the lattice column: arranging the material area far away from the inertial axis can ensure the bending resistance of the reinforced member under the same axial resistance condition and save material.
Main construction technology and key points of lattice column
1. Construction process
SR220C rotary drilling rig is used to form holes for temporary lattice column foundation bored piles. Rotary digging into a hole is firstly rotated by a bucket drill with a valve at the bottom, and directly loaded into the drill bucket, and then the drill bucket is lifted out of the hole by the drilling rig lifting device and the telescopic drill rod to unload the soil. Continue to take soil and unload the soil until the designed depth is reached. For rock and soil layers with good cohesiveness, dry or clean water drilling technology can be used, without mud protection
wall. For the loose and easy to collapse stratum, or with the distribution of groundwater, the hole wall is unstable, the static mud wall protection drilling technology must be adopted, and the wall protection mud is poured into the hole for wall protection. The construction process is shown in the figure below:
2. Key points of lattice column construction
1. Lattice column design requirements
The cross-section of the lattice column is 550×550mm, the angle steel model is ∠160×16, and the plaque model is 500×300×12@600 mm, and the steel member connections are all fully welded. The lattice column is embedded 15m below the base, that is, the bored pile is 15m long, and the steel column is embedded 3m. The steel column is welded with the main reinforcement of the bored pile and placed together. The bored pile has a diameter of 1200mm, and the vertical deviation of the pile body is ≤1/300 of the pile length.
2. Technical requirements for making lattice columns
① The lattice column is made of off-site steel structure. When the raw material enters the site, the quality certification documents are first reviewed and the appearance of the material is checked and accepted. After being qualified, the production is allowed. The finished lattice column shall be accepted for installation in accordance with "Code for Acceptance of Steel Structure Engineering Construction" GB50205-2001 and design requirements.
② The joints should be staggered during butt welding between lattice columns to ensure that the angle steel joints of the same section do not exceed 50%, and the staggered position of adjacent angle steels is not less than 50cm. The angle steel joint is reinforced with short angle steel of the same material on the inner side of the angle steel at the weld position.
