The principle and location of construction joint lien is actually very simple.

1, construction joint (construction joint) refers to the joint formed between the first concrete pouring and the last concrete pouring, which needs to be poured in sections due to design requirements or construction needs. Construction joints are not real "joints", but there is a joint between the first pouring concrete and the later pouring concrete, which is called construction joints.

2. The position of the construction joint should be set in a position where the shear force of the structure is small and convenient for construction, and should meet the following requirements: horizontal joints should be left for columns and walls, and concrete for beams and slabs should be poured at one time without construction joints. (1) Construction joints should be left on the top surface of foundation, under the support of beam or crane beam, above crane beam and below the column cap of flat floor. (2) For large-section beams integrated with the floor slab, construction joints shall be left at 20 mm ~ 30 mm below the floor slab bottom surface. When there is a beam support under the plate, it remains at the lower part of the beam support. (3) For the one-way slab, the construction joint should be left at any position parallel to the short side of the slab. (4) Floors with primary and secondary beams should be poured along the direction of secondary beams, and construction joints should be left in the middle 1/3 of the span of secondary beams. 5] Construction joints on the wall shall be left within the lintel span of the hole 1/3, or at the junction of vertical and horizontal walls.