JPH011836A - Construction method for prestressed steel reinforced concrete beams - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an erection method for rationally constructing a highly tough beam material made by combining a prestressed concrete beam with a steel frame in the construction of a building.

(Prior art) Prestressed concrete is high-strength concrete that is prestressed using prestressed steel, and has a small cross section and large yield strength, so it is an extremely useful member for single-girder beams, etc. It is widely used as a structural material in the fields of civil engineering and architecture.

On the other hand, in 1981, a major revision was made to the 11-gear seismic design method for buildings, and a transition was made to a method called the ``New Earthquake-resistant Design Method.'' This method differs from the concept of the "short-term allowable stress design method" before the revision, and is based on the vibration characteristics of the construction ground and the IM of the building.
This is a type of vibration analysis method that takes into account the right period and vibration response.

In addition, the resistance ability of buildings against earthquakes is also different from medium-sized earthquakes to large-scale earthquakes.
1! For the former, we apply the short-term allowable stress method (-order design) to prevent damage to the building, and for the latter, we apply the building's capacity calculation and deformation capacity. A study (secondary design) is conducted based on this to prevent the building from collapsing. Regarding the relationship between strength and deformation capacity (toughness or toughness), when a building exhibits an elastic response during an earthquake with a seismic intensity of In the case of a certain building, it is necessary to have both a yield strength and deformation performance equivalent to the energy resistance of the elastic response IG.

From the above points of view, it has been considered to incorporate a tenacious steel reinforced concrete structure into the prestressed concrete beam, which has the above-mentioned excellent high strength characteristics, to provide high toughness.
A structure has been developed that uses prestressing in combination with cast-in-place steel reinforced concrete beams and introduces prestressing using prestressed steel.

(Problem to be solved by the invention) In the construction of conventionally developed prestressed steel reinforced concrete, the steel reinforcing bars are placed at a location M.
A sheath for inserting the PC steel material was assembled into this, a formwork was applied, and cast-in-place concrete was poured. Then, the PC steel was inserted into the sheath.
A prestressed steel reinforced concrete beam is formed by inserting steel material and using the boss tension method.

Such a structure is extremely preferable because it has a small cross section and high strength and toughness compared to conventional structures.

However, it is not always easy to produce cast-in-place, high-strength, reliable concrete members, and there are also disadvantages such as increased construction time and an extension of the construction period.

When constructing such prestressed concrete steel reinforced concrete beams, the present invention precasts semi-finished beams (in-progress beams) under strict quality control in a factory or production yard, and transports and transports the in-process beams. The purpose of this project is to provide a labor-saving and lively construction method that is rational and allows for short construction periods.

[Means for solving problems]

The present invention consists of the following technical means.

(1) Precast prestressed concrete beams with the tops of the steel cross sections exposed on the upper surface of the concrete are manufactured.

In this case, the prestress may be introduced by either a pretension method or a post tension method. Also, Ji
I! The necessary prestressing for transportation and erection will be introduced as appropriate.

(2) Transport this work-in-progress beam to the construction site of the building.

The steel frames for the joint section are joined and assembled, and then the precast slab is placed on the semi-finished beams.Then, the formwork for the joint section, reinforcement for the semi-finished beams and slough, and prestressing steel are placed, and concrete is poured. and create a composite beam.

(3) After the concrete hardens, apply the necessary tension to the composite beam and complete the cast-in-place joint part as a prestressed steel reinforced concrete beam.

(Function) According to the present invention, a work beam can be manufactured using high-strength and highly reliable concrete under strict quality control.
By using these semi-finished beams, the erection work is streamlined, and it is possible to easily construct a building with a high strength and high toughness structure that has excellent seismic performance.

Such prestressed steel reinforced concrete beams may be of the pre-tension type or the post-tension type.

The weight and dimensions of such a work-in-progress beam can be determined by taking into account the moat force of the tower crane for transportation and construction, and it is convenient to form it with a protruding steel frame at the joint where it connects to the pillar. be.

Furthermore, by standardizing and generalizing this work-in-progress beam,
It is possible to improve the productivity of work-in-progress beams.

FIG. 2 is an explanatory diagram illustrating stress generated in a beam constructed by the method of the present invention.

When a beam with the cross section shown in Figure 2 (a) is manufactured and prestress is introduced, the stress generated in the cross section of the beam becomes as shown in Figure 2 (b), and the beam is transformed into the beam shown in Figure 2 (c). As shown in Figure 2 (d), when a load is applied after construction, the 110p stress due to the applied load is as shown in Figure 2 (d).
Therefore, the resultant stress is as shown in FIG. 2(e).

As is clear from Figure 2(e), this beam has a small stress α almost uniformly distributed over the entire cross section, and since no tension is generated in the concrete, it is possible to have a small cross section, and the yield strength is low. big. Furthermore, when seismic force is applied to this beam, it exhibits excellent toughness due to the elasticity of the steel frame, resisting repeated loads by drawing a large hysteresis curve, and absorbing a large amount of deformation energy.

(Example) A steel frame 2 and a sheath 4 whose cross section is shown in FIG. 1(a).
5. Rebar 6. A work beam l made of precast concrete 3 was manufactured. The in-progress beam l was manufactured taking into consideration the transportation and lifting capacity (IOT) of the tower crane.

The specifications of the in-process beams are as follows.

Span - 15m Steel frame = H-beam 5S-41 H600x200xl 1x17 Precast concrete: Compressive strength: 600kgf/crn' Width at double dimensions 400mm (Width at both ends is 500mm) Height 670mm PC cable: Mono strand IT 12,7 m mφ x 4 pieces For transportation and handling during erection, PCC Keral was inserted into sheath 4 (indicated by a black circle in SIUA) after the concrete had hardened. Introduced prestress.

2I of this shingle beam l at the construction site! As shown in FIG.
The end joint portions 12 of the two are connected to each other by means of a gazette plate 13.

Next, a precast slab 14 was placed on the in-progress beam 1, necessary reinforcing bars and sheaths 7 were placed, a formwork was provided at the joint part 15, and concrete 9 was poured.

Precast slab specifications: Model: Double T-shaped thin plate Subanni 6m Radius: 2m Slab thickness: 30mm Place cast slab concrete specifications: Compressive strength: 210kgf/cm' Thickness: 100mm This concrete placement is shown in Figure 1 (b). Thus, the beam and slab 9 were integrated to form a composite beam 8.

After the concrete hardened, a 12.7 mm φ PC cable was inserted through the sheath 5 for tensioning the beams in the first building and the sheath 7 placed at the site, and tension was applied to integrate the beams and columns.

This construction method has made it possible to easily construct beams that are inexpensive, highly reliable, and have high toughness.

〔Effect of the invention〕

According to the present invention, a high-toughness semi-finished beam made of prestressed concrete and steel reinforcing bars is precast and used for construction, resulting in high reliability, labor savings, and short construction times. Thick 'i! It is of extremely high practical value.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the construction method of the present invention, FIG. 2 is an explanatory diagram of stress in a prestressed steel reinforced concrete beam, and FIG. 3 is a construction diagram showing the joint structure of a beam and a column. l...Beam in progress 2...Steel frame 3...Concrete 4.5.7...Sheath 6...Rebar 8...Beam 9...-Slab 10...Column steel frame 11...・Column joint part steel frame 12--beam joint part 13--gusset plate 14--precast slab 15--joint part

Claims (1)

[Claims] 1. A prestressed concrete semi-finished beam with the top of the steel cross section exposed on the top of the concrete is manufactured in advance, the joint part of the semi-finished beam is connected to a column and assembled, and then a beam-shaped cross section and a slab including the steel frame exposed at the top are assembled. A construction method for prestressed steel reinforced concrete beams, which is characterized by simultaneously pouring concrete to form a composite beam.