JP2009228296A - Seismic strengthening method for bridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seismic strengthening method for a bridge, which can realize seismic strengthening without applying direct lining strengthening to a bridge pier, or which can decrease the level of the lining strengthening even if the lining strengthening is performed. <P>SOLUTION: The multispan bridge 1, in which a plurality of girders 2 continue in the direction of a bridge axis, is characterized in that the adjacent girders 2 and 2 can be connected together by means of a connecting device which is constituted to tie the girders 2 and 2 together in a range not exceeding the design expansion/contraction amount of an expansion joint device arranged between the adjacent girders 2 and 2, so as to prevent such a motion that a section between the girders 2 and 2 is opened/closed. A device, in which stoppers 5b and 5b are attached to both ends of a steel wire 5a with a predetermined length, or a seismic control damper is used as the connecting device 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a seismic reinforcement method for existing and new multi-span bridges.

  Of existing multi-span simple bridges with intermediate piers, those designed with the old standards are often very dangerous because they often do not meet the current seismic standards. In particular, when the deformation of the pier is large during a large-scale earthquake, for example, a bridge as shown in FIG. 3 (1) (two girder is formed by the abutments 53 and 53 installed at both ends and the pier 54 arranged in the middle. As shown in FIG. 3 (2), in the bridge 51 on which 52 and 52 are supported, the vicinity of the center of the bridge 51 (near the end of adjacent girder 52 and 52 supported by the pier 54). , It is displaced in the direction perpendicular to the bridge axis (the direction indicated by the arrow in the figure), and the movement between the adjacent girders 52, 52 may occur such that the end portions of the girders open and close, and the bridge is damaged. Or, there is a high possibility of collapse.

Therefore, for multi-span bridges that do not meet the current seismic standards, reinforcement of the piers is necessary, and as a concrete measure, reinforcing members such as reinforced concrete, steel plates, or carbon fiber sheets should be used. Construction (winding reinforcement work) is being carried out.
JP 2007-224579 A JP 2007-016500 A

  However, for river bridges and lake surface bridges where the piers are underwater, or bridges where the piers are in the soil of the slope, winding reinforcement work is physically impossible or physically possible. However, the cost is increased due to construction restrictions and the like, and the construction cannot be performed for economic reasons.

  The present invention has been made to solve such problems of the prior art, and can be realized without directly winding and reinforcing the pier, or even when the reinforcing reinforcement is applied, the level of reinforcement can be achieved. An object of the present invention is to provide a seismic reinforcement method capable of reducing the above.

  The seismic reinforcement method for a bridge according to the present invention is intended for multi-span bridges in which a plurality of simple girders are continuous in the direction of the bridge axis. It is characterized by the ability to reduce the horizontal displacement of the bridge pier by preventing the movement between adjacent girders against earthquake force. In addition, as a connection apparatus, it is preferable to use the thing which attached the stopper to the both ends of the steel material of predetermined length, or a damping damper.

  Moreover, the seismic reinforcement method for a bridge according to the present invention fixes the seismic inertial force of the superstructure against the seismic force perpendicular to the bridge axis by fixing the end of the beam supported on the abutment to the abutment. It is characterized in that it is handled by an abutment having a higher yield strength and rigidity than the pier, and that it is possible to prevent the girder from being displaced in the direction perpendicular to the bridge axis on the pier and the abutment. In addition, as a concrete means for fixing the end part of the girder to the abutment, a fixing device is erected on the abutment, or the end part of the girder is directly or directly on the abutment using an anchor. It is preferable to fix indirectly.

  According to the seismic reinforcement method for a bridge of the present invention, in a multi-span bridge, by connecting adjacent girders on a pier, or by fixing an end of a girder to an abutment, Even when a seismic force is applied in a perpendicular direction, it can be constrained so that adjacent girders do not open and close, and the behavior of a continuous girder (single bar) is close, and the seismic force is improved in strength and rigidity. It is divided into large abutments and can reduce the deformation of the pier. As a result, the seismic performance can be improved to a necessary level without reinforcing the piers. Moreover, the effect that the safety | security with respect to a falling bridge improves by connecting a girder to a bridge-axis direction can also be anticipated.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory view of a seismic reinforcement method for a bridge according to a first embodiment of the present invention. The reinforcement method according to the present invention is applied to a joint portion of girders 2 and 2 in a steel box girder type bridge 1. FIG. More specifically, FIG. 1 (1) is an end view of the girder 2 in the bridge 1 reinforced by the reinforcing method of the present invention, and (2) is a vertical sectional view of the girder 2 and 2 supported on the pier 4 ( (1) is a cross-sectional view taken along line xx), and (3) is a horizontal cross-sectional view of the girders 2 and 2 supported on the pier 4 (cross-sectional view taken along line yy of (1)).

  The bridge 1 in FIG. 1 was not connected between the adjacent girders 2 and 2 before application of the reinforcing method of the present invention (in addition, the floor slab 6 placed on the adjacent girders 2 and 2). 6 are connected by an expansion joint device (not shown) so that road surfaces are continuous.) After application, the adjacent beams 2 and 2 are firmly connected by the connecting device 5.

  In the present embodiment, the connecting device 5 is one in which stoppers 5b, 5b are attached to both ends of a steel wire 5a having a predetermined length, and each stopper 5b, 5b is connected to each digit 2, The steel wire 5a is stretched between the opposite beams 2 and 2 so as to be engaged with each other. In addition, the PC steel wire etc. which are used for manufacture of prestressed concrete (PC) can be used for the steel wire 5a. Moreover, as a structural member of the connecting device 5, instead of the steel wire 5a, a steel bar (PC steel bar or the like), other steel materials, or a damping damper (a damper using a low yield point steel material or the like) is included. Type dampers, friction history type dampers, viscous dampers, cylinder type dampers, etc.) can also be used. Further, the stopper 5b may be configured to be locked to a bracket formed on the wall surface of the girder 2 instead of being directly locked to the wall surface of the beam 2.

  The connecting device 5 has a structure capable of absorbing the amount of movement due to deflection caused by temperature changes of the girders 2, concrete creep and drying shrinkage, and live loads (for example, the length of the steel wire 5a is increased by the amount of temperature expansion or contraction, or a stopper. 5b and a structure in which a gap is provided between brackets formed on the wall surface of the girder 2).

  Further, the connecting device 5 restrains the girders 2 and 2 within a range not exceeding the “design expansion amount” of the expansion joint device (not shown) disposed between the adjacent girders 2 and 2. It is configured. More specifically, in this case, when the distance between the adjacent girders 2 and 2 is smaller than “a certain value” (here, this value is referred to as “limit value”), the connecting device 5 The adjacent girders 2 and 2 are in a state of being loosely coupled with a margin, but when the separation dimension between the adjacent girders 2 and 2 reaches the “limit value”, the coupling device 5 It is tense and prevents further expansion between digits 2 and 2. The “limit value” is set in a range not exceeding the “design expansion amount” of the expansion joint device.

  The “design expansion amount” of the expansion joint device is set for each installed girder in consideration of the temperature change of the girder, the creep and drying shrinkage of the concrete, the amount of movement of the superstructure due to the deflection caused by the live load, etc. Generally, it is calculated by the following formula.

Bridge type Basic expansion and contraction (unit: mm)
For steel bridge: 0.6L
For steel bridges in cold regions: 0.72L
Reinforced concrete bridge: 0.4L + 0.2Lβ
Reinforced concrete bridge in cold region: 0.5L + 0.2Lβ
Prestressed concrete bridge: 0.4L + 0.6Lβ
Prestressed concrete bridge in cold region: 0.5L + 0.6Lβ

  In the above formula, “L” is the length of the expansion / contraction digit (unit: m), and “β” is the reduction coefficient. The reduction factor β is “0.6” if the concrete age is 1 month, “0.4” if it is 2 months, “0.3” if it is 6 months, and if it is 12 months In the case of “0.2” and 24 months, “0.1” is set. Furthermore, a margin (basic expansion / contraction amount × 20%, but a minimum of 10 mm) is added to the basic expansion / contraction amount.

  With respect to the connecting device 5, the “limit value” of the separation distance between the adjacent girders 2 and 2 is set within a range not exceeding the “design expansion amount” of the expansion joint device. When the space between the connecting devices 5 increases, the connecting device 5 is in a tensioned state before the distance between the distances reaches the “design expansion amount” of the expansion joint device disposed therein, This means that it does not expand, and that the space between the girders 2 and 2 is constrained not to expand to the “design expansion / contraction amount”.

  According to the invention according to the present embodiment, by connecting the girders 2 and 2 with the coupling device 5 having the above-described configuration, the bridge axis is perpendicular to the girders 2 and 2 in a large-scale earthquake. Even when a force that swings to the side acts, it is possible to prevent the movement between the adjacent girders 2 and 2 from being opened and closed. As a result, the bridge shaft as shown in FIG. The displacement of the girder in the perpendicular direction or the deformation of the pier can be preferably avoided.

  In this embodiment, the example in which the reinforcing method according to the present invention is applied to the steel box girder type bridge 1 has been described. However, the type of bridge girder to be applied is the steel box girder. The present invention is not limited, and can be applied to any girder bridge such as a concrete T girder and a steel plate girder. Also, the form of the pier is not limited to a single pillar type pier, but can be applied to bridges having any type of pier such as a wall type, a ramen, and a steel pier. Furthermore, the present invention can be applied not only to existing bridges but also to new bridges.

  FIG. 2 is an explanatory view of the seismic reinforcement method for a bridge according to the second embodiment of the present invention. The reinforcement method of the present invention is applied to a joint between a girder 2 and an abutment 4 in a concrete box girder type bridge 1. It is a figure which shows the example applied with respect to. More specifically, FIG. 2 (1) is a vertical sectional view (vertical sectional view in a direction perpendicular to the bridge axis) of the beam 2 in the bridge 1 reinforced by the reinforcing method of the present invention, and (2) is a support on the abutment 3. It is a vertical sectional view (sectional view taken along line zz in (1)) of the girders 2 to be used.

  In the bridge 1 of FIG. 2, the end of the girder 2 supported on the abutment 3 was not fixed to the abutment 3 before application of the reinforcing method of the present invention. The two fixing devices 7 and 7 erected on the base 3 are fixed so that the girder 2 is sandwiched from the side, and in a large-scale earthquake, the force swings in a direction perpendicular to the bridge axis with respect to the girder 2 Even when this occurs, it is possible to prevent the girder 2 from being displaced in the direction perpendicular to the bridge axis on the abutment 3 and to suitably avoid the deformation of the pier.

  In the present embodiment, the example in which the reinforcing method according to the present invention is applied to the concrete box girder type bridge 1 has been described. However, as in the first embodiment, the bridge girder to be applied is applied. There is no limitation on the type of steel, and it can be applied to any girder bridge such as steel box girder, concrete T girder, steel plate girder, etc., and can be applied to both existing and new bridges. It is.

  Moreover, in this embodiment, the fixing device 7 includes a steel box-shaped main body 7a, an anchor 7b embedded in the abutment 3 in order to fix the main body 7a on the abutment 3, a main body 7a and a girder. Although it is comprised by the buffer material 7c arrange | positioned between 2 side wall surfaces, it is not limited to the thing of such a structure, It can prevent that the girder 2 is displaced to a bridge axis orthogonal direction on the abutment 3. As long as it has any configuration.

  For example, the fixing device may be composed of reinforced concrete, and a space (two parallel girders 2 and 2 in the lower center portion of the floor slab 6 as in the bridge 1 shown in FIG. 1 (1). If the fixing device is erected in the center of the abutment and the fixing device is straddled by two parallel girders 2 and 2, that is, the fixing device is installed in the girders 2 and 2 It is also possible to adopt a configuration in which the movement of the beam 2 on the abutment 3 (displacement in the direction perpendicular to the bridge axis) is restricted by entering the space between them. Further, in a bridge using a girder in which a plurality of I-shaped steels are arranged in parallel with a predetermined interval in a direction perpendicular to the bridge axis in a direction in which the longitudinal direction is parallel to the bridge axis direction, ) The lower flange can be fixed directly to the abutment using an anchor with the lower half embedded in the abutment, or indirectly fixed with some material in between. good.

Explanatory drawing of the earthquake-proof reinforcement method of the bridge which concerns on the 1st Embodiment of this invention. Explanatory drawing of the earthquake-proof reinforcement method of the bridge which concerns on the 2nd Embodiment of this invention. Explanatory drawing about the displacement of the girders 52 and 52 which may arise in the bridge 51 between many diameters at the time of a large-scale earthquake.

Explanation of symbols

1,51: Bridge,
2, 52, 52: digits,
3, 53, 53: Abutment,
4,54: Pier
5: Connecting device,
5a: steel wire,
5b: stopper,
6: Floor slab,
7: fixing device,
7a: body,
7b: anchor,
7c: cushioning material

Claims (6)

A seismic reinforcement method for multi-span bridges in which multiple simple girders continue in the direction of the bridge axis,
By connecting the adjacent girders on the pier with a connecting device configured to constrain the girders in a range not exceeding the design expansion and contraction amount of the expansion joint device arranged between the adjacent girders, A seismic reinforcement method for bridges, which prevents the movement of adjacent girders from opening and closing against the seismic force in the direction, enabling the horizontal displacement of the pier to be reduced. A seismic reinforcement method for multi-span bridges in which multiple simple girders continue in the direction of the bridge axis,
A method for seismic reinforcement of a bridge, characterized in that the end of the girder supported on the abutment is fixed to the abutment so that the girder can be prevented from being displaced in the direction perpendicular to the bridge axis on the abutment. . A seismic reinforcement method for multi-span bridges in which multiple simple girders continue in the direction of the bridge axis,
By connecting adjacent girders on the pier with a coupling device, against the seismic force in the direction perpendicular to the bridge axis, the movement of the adjacent girders to open and close can be prevented, and the horizontal displacement of the pier can be reduced, Furthermore,
By fixing the end of the girder supported on the abutment to the abutment, the super inertia's seismic inertial force is handled by the abutment with higher proof strength and rigidity than the pier against the seismic force perpendicular to the bridge axis. An anti-seismic reinforcement method for a bridge, characterized in that the girder can be prevented from being displaced in the direction perpendicular to the bridge axis on the pier and abutment.   The method of seismic reinforcement of a bridge according to claim 1 or 3, wherein a steel plate having a predetermined length is used as the connecting device, or a damping damper is used.   4. The method for seismic reinforcement of a bridge according to claim 2 or 3, wherein a fixing device is erected on the abutment to fix the end of the beam to the abutment.   4. The method for seismic reinforcement of a bridge according to claim 2, wherein an end of the beam is fixed directly or indirectly on the abutment using an anchor.

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