When will precast lintels and cast-in-place lintels be used for building doors and windows?

If the distance between the door and window top and the floor beam is greater than the height of the window lintel, it can be prefabricated or cast in place.

If the distance between the top of the door and window and the beam slab is less than the height of the window lintel, or the top of the window is just at the bottom of the beam slab, it can be cast in place.

There are no walls on both sides of doors and windows, only frame columns and the like, which can only be cast in place.

For special purposes such as Rachel, cast-in-situ casting is adopted.

Body, the lintel above the load-bearing wall also bears the floor pressure. There are three structural modes of lintel.

(1) Reinforced concrete lintels have strong bearing capacity and can be used for large openings, which are generally as thick as walls, and the height should be calculated and determined. The length of both ends extending into the wall should not be less than 240 mm

(2) Comment on arch brick lintel and brick side masonry. The mortar joint is wide at the top and narrow at the bottom, and the brick inclines to both sides to form an arch. The lower parts of both ends penetrate into the wall for 20-30mm, and the middle arching height is 1/50 of the span. The advantage is that the amount of steel bars and cement is small, but the disadvantage is that the construction speed is slow, the span is small, there is concentrated load or the semi-brick wall is not suitable for use.

(3) The reinforced brick lintel is reinforced at the top of the hole to form a reinforced brick masonry. The rebar diameter is 6mm, the spacing is less than 120mm, and the rebar extends into the walls at both ends not less than 240 mm. This method is the same as the external wall masonry method, which can form a complete fair-faced brick wall effect, but the construction is troublesome and the span is less than 2 m.