JPH04319154A - Long span precast-concrete beam - Google Patents

Abstract

PURPOSE:To increase allowable stress for teh cross-ssectional area bending of a beam member and increase strength rigidity by composing U-shaped stel frame members set respectively orghogonally to the upper end surfaces of precaste concrete beams, integrally to be embedded on the central section leaving both the end sections in the longitudinal direction of the beam. CONSTITUTION:From an end surface in the longitudinal direction, the set end sections of beam lower-end main-reinforcements 2 are projected, and on the loss sections of slab cross-sectional-areas, the upper ends of reinforcements 3 are saliently arranged. Then, leaving both the end sections of a beam member 1, to the central section, U-shaped steel frame members 4 provided with horizontal flanges 4b at the upper ends of both side vertical-section pieces 4a are orghogonally embedded, and between the steel frame members 4, a hollow section 1a with the opened upper end is placed, and stud connectors 5 are erected. Besides, on the flanges 4b, stud connectors 6 are erected. As a result, allowable stress is increased more than that for conventional U-shaped steel frame material, and the cross-sectional area of a precast concrete beam can be diminished.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a long span precast concrete beam.

0002

[Prior Art] In Japanese Patent Application No. 2-122898, the present inventor integrally buried a U-shaped steel frame with an open top end in the center of a precast concrete beam member, leaving both longitudinal ends intact. A long span precast concrete beam was proposed.

0003

[Problems to be Solved by the Invention] The steel frame embedded in the precast concrete beam has a U shape with an open upper end.
Since the beam is formed into a cross-sectional member, the bending allowable stress of the steel frame material is insufficient, and the cross-section of the beam member increases. The present invention has been proposed in view of the problems of the prior art, and its objectives are to increase the allowable bending stress of the steel frame embedded in a beam member, reduce the cross section of the beam member, and Another object of the present invention is to provide a long span precast concrete beam that can be integrated with a slab constructed on top of a beam member and increase the strength and rigidity of the slab.

0004

[Means for Solving the Problems] In order to achieve the above object, the long span precast concrete beam according to the present invention is provided with upper horizontal flanges perpendicular to the upper end surfaces of both vertical parts. A U-shaped steel frame member is integrally buried in the center of a precast concrete beam member, leaving both ends in the longitudinal direction intact.

[0005]

[Operation] In the long-span precast concrete beam according to the present invention, in the central part of the beam, leaving both ends in the longitudinal direction, and in the upper ends of both vertical parts of the U-shaped cross-sectional member,
Furthermore, a U is provided with an upper horizontal flange perpendicular to the vertical part.
Since the U-shaped steel frame member is buried as one piece, the allowable stress of the U-shaped steel frame member is higher than that of the U-shaped steel frame member in the conventional precast concrete beam without an upper horizontal flange.

[0006] Furthermore, by using the upper horizontal flanges provided at the upper ends of the vertical pieces on both sides of the U-shaped steel frame member, stud bolts are planted on the upper surfaces of the flanges.
The precast concrete beam and the slab constructed on the beam are integrated, and the rigidity of the slab can be increased.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. 1 is a precast concrete beam member that has a length spanning between adjacent columns and has a cross-sectional shape in which the slab cross section is missing;
The fixed end portion 2a of the beam lower end main reinforcement 2 is provided to protrude from the longitudinal end face, and the upper end of the rib 3 is provided to protrude above the slab cross-sectional defect.

A U-shaped steel frame member 4 is buried in the center of the beam member 1, leaving both ends in the longitudinal direction, and is provided with an upper horizontal flange 4b perpendicular to the vertical pieces 4a at the upper ends of the vertical pieces 4a on both sides. A stud dowel 5 is welded to the opposing surfaces of the vertical pieces 4a on both sides, which are formed in the beam member 1 by the same steel frame member 4 and are opposed to each other across the hollow portion 1a with an open upper end. A stud dowel 6 or a reinforcing bar is erected on the horizontal flange 4b by welding.

[0009] Concrete retaining plates 7 made of perforated plates such as metal lath are provided on both longitudinal end faces of the steel frame member 4.
will be placed. During construction, the precast concrete beam members 1 are constructed between columns with missing beam sections, and semi-precast concrete floor plates are constructed between adjacent beam members 1 to reinforce the column heads. Arrange reinforcement, main reinforcement at the top of the beam, and slab reinforcement, and pour concrete for the slab and column head.

At this time, the post-cast concrete is integrated with the U-shaped steel frame member 4 via the stud dowel 5, and the slab is further integrated with the beam via the stud dowel 6. In the beam integrated with the U-shaped steel frame member 4 in this way, the U-shaped steel frame member 4 functions similarly to a steel frame member. Moreover, since the U-shaped steel frame member 4 is provided with upper horizontal flanges 4b perpendicular to the upper ends of the vertical pieces 4a on both sides thereof, the allowable bending stress of the steel frame member is lower than that of the upper horizontal flanges 4b. It is larger than the U-shaped steel frame member, and the cross section of the precast concrete beam 1 can be made smaller, and the floor height can be lowered accordingly.

Furthermore, by installing stud bolts 6 on the upper horizontal flange 4b, the slab and precast concrete beam 1 are integrated, the rigidity of the slab is increased, and the strength of the building is increased. be.

0012

[Effects of the Invention] In the long span precast concrete beam according to the present invention, the beam is placed in the center of the beam except for both ends in the longitudinal direction, and in the upper end of both vertical parts of the U-shaped cross-section member. Since the U-shaped steel frame member with the upper horizontal flange orthogonal to the upper part was buried as one piece, the U-shaped steel frame member is better than the U-shaped steel frame member in the conventional precast concrete beam without the upper horizontal flange. The allowable stress is increased and the cross section of the precast concrete beam can be reduced.

[0013] Furthermore, by using the upper horizontal flanges provided at the upper ends of both vertical pieces of the U-shaped steel frame member, stud bolts are planted on the upper surfaces of the flanges.
The rigidity of the slab constructed on the precast concrete beam can be increased.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of a long span precast concrete beam according to the present invention.

FIG. 2 is a side view of the precast concrete beam.

FIG. 3 is a longitudinal sectional side view of the precast concrete beam.

[Explanation of symbols]

1 Precast concrete beam member 4
U-shaped steel frame member 4a Vertical pieces 4b on both sides Upper horizontal flange 6 Stud dowel

Claims (1)

[Claims] Claim 1: A U-shaped steel frame member provided with upper horizontal flanges perpendicular to each vertical member on the upper end surfaces of the vertical members on both sides is integrated into the central part of the precast concrete beam member, leaving both longitudinal ends of the member intact. A long span precast concrete beam characterized by being buried in.