JPH0796841B2 - Seismic reinforcement structure with existing RC steel frame - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application Field >> The present invention relates to a steel frame-based seismic element that improves seismic performance of an opening of a reinforced concrete structure (RC structure), and an existing seismic element is provided in the opening. It is related to the seismic retrofit structure by the steel frame of the RC image.

<Conventional technology> When constructing a building frame with reinforced concrete, the cross-sectional area of columns and beams was increased in order to improve seismic performance. As another means, add a sleeve wall to the pillar,
The earthquake-resistant wall will be added by post-casting, the wall thickness of the earthquake-resistant wall will be increased and the opening will be buried, or the strength-resistant steel braces will be added.

<Problems to be solved by the invention> Increasing the cross-sectional area of columns and beams will reduce the living space and increase the weight. In addition, since the seismic wall does not have high toughness, the weight increases due to the need to increase the strength, and the usability of the building is poor due to the lack of openings. Moreover, the conventional reinforcing means would not have sufficient reinforcing effect unless it was applied to the entire building.
Since there are many construction sites and the total weight increases significantly, it may be necessary to reinforce the foundation.

The strength-resisting steel brace has a large partial stress, which is disadvantageous in terms of workability for increasing the member cross section and increasing the joint strength.

Therefore, a toughness-resistant steel frame brace in which a steel frame is added inside the rectangular opening of a reinforced concrete structure and a "Y" -shaped brace is arranged in this frame is also considered.
Tensile stress concentrates at the joint between the vertical piece of the character-shaped brace and the frame, and this local stress eventually demands the required strength for the beam or column, so of course workability and quality control are difficult. In some cases, reinforcement of existing beams was necessary.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an earthquake-proof reinforcement structure in which an excellent toughness-resistant steel frame brace is arranged in an opening of a building when performing earthquake-proof reinforcement of an existing reinforced concrete structure. It is in.

<< Means for Solving the Problem >> In order to achieve the above-mentioned object, the seismic retrofit structure by the steel frame of the existing RC structure according to the present invention is left-right or up-down in the rectangular opening of the existing RC structure, either symmetric. A steel frame member was additionally provided at the position, one end of the elasto-plastic shear panel was rigidly connected to the frame member, and the other end was connected with a brace pin-joined to the opening body by pin-joining. In order to secure a wide opening, the brace has a vertical line shape or a horizontal line shape, and its end is pin-joined to the RC structure of the opening. For the purpose of improving the workability by reducing the number of joints, the brace is a rhombus in which each corner is assembled in a pin joint, and the pair of symmetry angles is pin-joined to the pair of elastic-plastic shear panels, and the other pair of symmetry angles is It was pin-joined to the RC structure at the opening. Further, in order to smoothly bear only the axial force on the brace, the brace has a “<” shape or an inverted “<” shape inclined from the pin joint portion with the elasto-plastic shear panel toward the center of the opening. I did.

<< Working >> According to the above structure, the moment does not act on the pair of sides of the RC structure, and the axial force also acts on the brace, and the bending moment does not act.

Then, the elastic force composed of the brace and the elasto-plastic shear panel resists the deformation of the opening, which yield buckles when subjected to the deformation stress exceeding the shear resistance of the elasto-plastic shear panel held in advance, and the RC structure opening. Plastic deformation prior to the collapse of the part.

<Example> Hereinafter, a preferred example of the present invention will be described in detail with reference to the drawings.

Figure 1 shows a reinforced concrete structure (RC structure) pillar 1-beam 2
A frame member 4 made of H-shaped steel fixed by stud bolts along the pillar 1 is provided in a rectangular opening 3 surrounded by, and an elasto-plastic shear panel (hereinafter, simply sheared) is provided at an intermediate position in the longitudinal direction of the frame member 4. Panel 5) is fixed horizontally.

That is, the shear panel 5 symmetrically protrudes slightly from the left and right in the opening 3. Then, a brace 6 having a length substantially equal to the height of the opening 3 is pin-joined to the projecting end of the shear panel 5, and the brace 6 is positioned substantially vertically so that the ends of the brace 6 and the upper beam 2 are positioned below each other. The gusset plate 7 fixed to the side beam 2a is pin-joined.

An axial force and a moment act on the frame member 4 against the deforming force, and a bending moment and a shear force act on the base portion on the shear panel 5. A vertically long opening can be secured without applying a moment to the beams 2 and 2a. The elastic force of the shear panel 5 opposes the deformation force of the opening 3. However, if the toughness resistance of the shear panel 5 is exceeded, the shear panel 5 yields and buckles before the columns 1 and 2 collapse. .

Therefore, the frame member 4 also has an effect of making the rigidity strong enough to bear the vertical load even if the existing pillar 1 is broken and distributing local stress. That is, this is because the frame member 4 bears the moment generated by the shear stress acting on the shear panel 5, and similarly, an embodiment using the rigid frame member 4 and the shear panel 5 is shown in FIGS. 2 and 3. .

That is, the joint between the shear panel 5 and the frame member 4 is rigid, and in the embodiment shown in FIG. 2, the number of pin joint portions with the beams 2 and 2a is reduced to one point, and each joint point where the shear panel 5 and the beam 2 are in contact with each other. Is connected to the rhombus with a brace member, so-called rhombus brace 8
It is what constitutes.

The braces are assembled to the diamond-shaped brace 8, the upper and lower diagonal points are pin-joined to the respective beams 2 and 2a, and the shear panel 5 is pin-joined to the left and right diagonal points.

Since the stress is dispersed and transmitted to the existing frame forming the opening 3 and the frame member 4 bears the moment, it is not necessary to increase the number of post-installed anchors of the frame member 4 or to reinforce the column 1 and calculate the yield strength. become.

This is particularly noticeable when the opening 3 of the existing RC body is continuous in the vertical direction in a straight line, and the moments do not act on the beams 2 and 2a, and the inclination of the diamond-shaped brace that is continuous in the vertical direction. It acts linearly in the direction by the axial force, and transmits the deformation stress to the shearing panels 5 in the vertically adjacent openings.

The embodiment shown in FIG. 3 differs from the embodiment shown in FIG. 2 in that the upper and lower joining points of the diamond-shaped brace 8 are separated from each other to the left and right. That is, in order to separate in the left-right direction, the shear panel 5 may be shortened and separated from the left-right direction by that amount, but here, the inclination angle of the diagonal member forming the diamond-shaped brace 8 is loosened. As a result, a substantially "V" -shaped brace 9 in which the longitudinal center portion is pin-bonded to the shear panel 5 is obtained. However, in this case, the axial direction of the slanting "<"-shaped brace 9 does not continue in the upper and lower floors, so the stress acting on the vertical beams 2, 2a becomes severe, but In addition to being able to secure the opening 10 for the passage as shown by the dotted line, the axial force acting on the "b" -shaped brace 9 is more sensitive to the deformation of the opening 3 as compared with the embodiment shown in FIG. In addition, since the bending moment acting on the shear panel 5 is also increased, the performance of the shear panel 5 can be quickly extracted. That is, a reaction sensitive to the behavior of deformation can be performed.

<Effect> As described in detail above, the seismic retrofit structure using the existing RC steel frame according to the present invention is lighter than the reinforced concrete seismic wall because the braces are made of iron, which has a higher strength per unit weight than concrete. , Is advantageous in that the weight of the building is not increased.

That is, it is generally difficult to reinforce the foundation, but there is no need to reinforce the foundation, and the seismic input increases in proportion to the weight of the building, but after the reinforcement, the seismic input is almost the same as before the reinforcement. , Reinforcement efficiency is better than other conventional reinforcement methods that increase the weight of the building.

Similarly, in terms of reinforcement efficiency, in the reinforcement method of adding a reinforced concrete earthquake-resistant wall, the seismic performance deteriorated when windows and doors were installed, but the present invention allows the opening to be set without compromising the seismic performance. Is.

In addition, the elasto-plastic shear panel and the brace absorb the deformation stress, and the elasto-plastic shear panel is kept above a certain seismic force.
It can be set so that it will yield before the RC structure so that the brace does not buckle or yield.

Therefore, since the toughness of the present invention is better than that of the conventional strength-resistant braces, the strength of the steel frame member may be reduced in order to obtain the same seismic performance as the strength-resistant braces.

Therefore, the cross section of the steel frame member can be made small, which is economical, the weight increase is small, and the reinforcing efficiency is improved. Furthermore, since the joint stress with the reinforced concrete frame is also small, the strength of this joint part may be low, and it is possible to reduce the amount of joint reinforcements such as anchors and studs required for joining with the existing concrete skeleton. so,
Construction becomes easy and the construction period and construction cost can be reduced.

Since the elasto-plastic shear panel has moderate strength and large toughness, it can absorb a large amount of energy during an earthquake.By focusing damage on the elasto-plastic shear panel, most of the seismic energy added to the entire building is elasto-plastic. It is possible to absorb it in the shear panel, so that
It also has a damping effect that functions as a damper that reduces the response deformation of the building to reduce damage, and makes it easy to repair reinforced concrete frames after an earthquake.

That is, it is sufficient to replace the elasto-plastic shear panel, which has the effect of facilitating repair.

Furthermore, the elasto-plastic shear panel and brace can be attached to the RC building opening only when a large earthquake is predicted, and can be used as an open space normally.

Also, since the frame member can be easily removed by disconnecting the frame member from the opening, it is easy to replace with a seismic resistant structure with different brace inclination angles and different plastic-shear panel mounting positions. It is also possible to change the position dimensions of.

If the RC structure has good toughness, the behavior of the elasto-plastic shear panel is not wasted, which is particularly effective.

Since the present invention has a high reinforcing efficiency, it is possible to reduce the construction site. That is, it is possible not only to reduce the construction period and construction cost but also to flexibly cope with construction during use of the building, which is particularly advantageous for construction of buildings such as hospitals and inns where the use of the building cannot be interrupted. .

In addition, it can be similarly incorporated into a steel-framed reinforced concrete building as a seismic element, and can be applied to civil engineering structures such as railway bridges and road bridges. Also,
Braces of this configuration can also be incorporated into new buildings.

When the vertical brace is placed separately on the left and right inside the opening, a wide passage opening can be secured in the opening, and if a diamond-shaped brace is used, pin connection points can be reduced and the upper and lower floors are continuous. , The brace is continuous in the vertical direction, and the entire building can be complementarily and efficiently reinforced.

In addition, when the brace has a V shape, the behavior of the elasto-plastic shear panel with respect to the amount of deformation of the opening reacts quickly and becomes large, so that there is an effect that sensitive seismic resistance can be achieved.

[Brief description of drawings]

Each of the drawings relates to an embodiment of the present invention. FIG. 1 is a schematic configuration diagram in which a brace is in a "to" shape, and FIG. 2 is a schematic configuration diagram in which a brace is in a rhombus shape. The figure is a schematic configuration diagram in which the brace has a V-shape. 1 ... Pillar, 2 ... Beam 3 ... Opening, 4 ... Frame member 5 ... Elasto-plastic shear panel, 6 ... Brace 7 ... Gusset plate, 8 ... Rhombic brace 9 ... V-shaped brace 10 ... Aisle opening

Claims (4)

[Claims] 1. A steel frame member is additionally provided at a left-right or upper-lower symmetrical position in a rectangular opening of an existing RC structure, and one end of an elasto-plastic shear panel is rigidly connected to the frame member, A seismic retrofit structure using an existing RC steel frame, in which a brace that is pin-joined to the opening body is joined to the other end by pin-jointing. 2. The seismic retrofit structure of existing RC steel frame according to claim 1, wherein the blazes are vertical or horizontal lines, and the ends thereof are pin-bonded to the RC structure of the opening. 3. The blaze is a rhombus in which each corner is assembled into a pin joint, a pair of symmetry angles of which is pin-joined to a pair of elasto-plastic shear panels, and another pair of symmetry angles is a RC structure of the opening. The seismic strengthening structure using an existing RC steel frame according to claim 1, wherein the structure is pin-joined. 4. The brace is formed in a "C" shape or an inverted "C" shape that is radially inclined from the pin joint portion with the elasto-plastic shear panel toward the center of the opening. Seismic strengthening structure with existing RC steel frame described in 1.