JP6187152B2 - Ramen structure design method - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a ramen structure design method, and specifically relates to a technique that enables the design of a structure that avoids the effects of drying shrinkage of concrete and has good workability and economy.

  In concrete after placing, drying of the cement paste in the interior progresses with time, and drying shrinkage occurs. Since the occurrence of such drying shrinkage causes cracks in the concrete and further causes functional deterioration associated with the cracks, various suppression techniques have been proposed. That is, self-shrinkage and drying shrinkage of concrete, mortar, etc. are reduced at least to the extent that cracks due to shrinkage can be sufficiently prevented, and other properties of concrete, mortar, etc. are not excessively affected. A technique related to a shrinkage inhibitor for cement blending that can prevent the occurrence of cracking with a relatively small blending amount (see Patent Document 1) has been proposed.

Japanese Patent Application Laid-Open No. 2004-299989

  On the other hand, the above-mentioned drying shrinkage is not only an effect of cracks and the like at a corresponding location, but also a phenomenon that exerts a tensile stress and a bending stress on a structure coupled with the occurrence location. The influence of this bending stress is particularly strong in a rigid frame structure in which each part is rigidly connected. Therefore, when designing a rigid frame structure, it was necessary to examine in detail appropriate reinforcing measures such as increasing the amount of bar arrangement at a predetermined site in order to withstand bending stress due to drying shrinkage.

  However, such reinforcement measures have been studied without taking into consideration the situation when the above-described drying shrinkage is suppressed. In other words, the design is performed on the premise that the above-mentioned bending stress acts as it is despite adopting measures to suppress drying shrinkage, and as a result, the design bar arrangement amount of the corresponding part where the bending stress acts is larger than the required amount. Only certain design results can be obtained. Therefore, compared to a case where an appropriate design bar arrangement amount is determined, the bar arrangement work becomes complicated and costs increase. In addition, when it is found that various loads such as the bending stress mentioned above are applied beyond the initial assumption regarding the part where the bar arrangement or concrete placement has already been completed, additional measures such as coating the outer periphery of the part with a steel plate, etc. Reinforcement measures were required, and work efficiency and cost could be further deteriorated.

  Then, this invention aims at provision of the technique which can design the structure which avoids the influence by the drying shrinkage | contraction of concrete and has favorable workability and economical efficiency.

  A ramen structure design method for solving the above-mentioned problem is a method for designing a ramen structure comprising a plurality of structures and a concrete member laid between the structures, and the amount of drying shrinkage in the concrete member is reduced. Based on the addition amount calculation step of calculating the addition amount of the expansion material to the concrete member to suppress the drying shrinkage amount, and the structure shrinking due to the addition of the expansion material, the amount of drying shrinkage A bar arrangement calculating step of calculating a cross-sectional force reduced according to the amount of restraint and performing a bar arrangement calculation related to the structure based on the reduced cross-sectional force.

According to this, for example, the effect of drying shrinkage suppression on horizontal members (eg, bridge girder and pier girder) of a rigid frame structure, that is, vertical members (eg: bridge piers and foundations of bridges) coupled to the horizontal member. In addition, the structure in which the amount of bar arrangement in the vertical member is appropriately suppressed can be designed in consideration of the effect of relaxation of the static destabilizing force in (part). Therefore, it is possible to design a ramen structure that provides good workability and economical efficiency in the bar arrangement process. In other words, it is possible to avoid the influence due to drying shrinkage of the concrete and to design a structure with good workability and economy.
Further, in the above-described method for designing a ramen structure, in the addition amount calculating step, an expansion material is added in an addition amount of a plurality of patterns to the test concrete having the same specifications as the concrete member, and the addition amount of each pattern is Based on the test result of measuring the expansion amount of the test concrete, calculating the relationship between the expansion material addition amount and the expansion amount in the concrete member, and the expansion amount of the concrete member that suppresses the drying shrinkage amount And applying to the relationship, and calculating the addition amount of the expansion material. In addition, the concrete for a test at the time of expansion | swelling material addition is concrete before complete hardening, and mainly ready-mixed concrete. On the other hand, the concrete for a test at the time of measuring the amount of expansion corresponds to, for example, concrete having an age of 7 days.

  According to this, it is possible to obtain a value that accurately corresponds to each characteristic of the concrete member to be added and the expansion material with respect to the addition amount of the expansion material, and thus avoids the influence of the drying shrinkage of the concrete with high accuracy. In addition, it is possible to design a structure that further improves workability and economy.

  Further, in the addition amount calculation step of the above-described ramen structure design method, the calculated addition amount of the expansion material is included within a reference range determined with respect to the construction quality of the addition of the expansion material, and in each pattern described above. A step of determining whether or not the result of the compressive strength test performed on the test concrete satisfies the material strength necessary for the concrete member, and as a result of the determination, the conditions are satisfied. A step of determining the calculated addition amount of the expansion material as a design value when it is determined that the expansion amount is determined.

  According to this, regarding the addition amount of the expansion material, both the construction accuracy when adding the expansion material to the concrete member (such as the uniform dispersibility in the addition destination concrete and the control accuracy of the expansion amount) and the member strength after the addition of the expansion material It is possible to obtain a value that can achieve a good state, and consequently avoid the effects of drying shrinkage of the concrete with good precision, taking into account the construction accuracy of the expansion material and the strength of the member after the addition of the expansion material, workability and economic efficiency Therefore, it is possible to design a structure in which is improved.

  The method for designing a ramen structure according to the present invention is a design method for a ramen structure comprising a plurality of structures and a concrete member laid between the structures, and the ramen structure has already been constructed among the ramen structures. For the structure, calculate the sectional force generated under the predetermined conditions from now on, and if the calculated sectional force exceeds the predetermined standard, to suppress the sectional force with respect to the unconstructed concrete members that are combined with the structure The addition amount calculation process of calculating the addition amount of the expansion | swelling material of the said concrete member is characterized by the above-mentioned.

According to this, various loads such as bending stress described above are initially assumed for structures (for example, bridge piers and foundations) of ramen structures in which reinforcement and concrete placement have already been completed. Even if it is found that this is the case, it should be added to the horizontal member (eg bridge girder or bridge pier girder) that is connected to the above structure in order to suppress the cross-sectional force acting on the corresponding structure. It becomes possible to determine the amount of the expansion material to be added. Therefore, additional reinforcement measures such as covering the outer periphery of the structure with a steel plate are not necessary, and work efficiency and cost deterioration can be avoided. In other words, it is possible to avoid the influence due to drying shrinkage of the concrete and to design a structure with good workability and economy.
Further, in the above-described method for designing a ramen structure, in the addition amount calculating step, an expansion material is added in an addition amount of a plurality of patterns to the test concrete having the same specifications as the concrete member, and the addition amount of each pattern is Based on the test results of measuring the expansion amount of the test concrete, the step of calculating the relationship between the expansion material addition amount and the expansion amount in the concrete member, and suppressing the cross-sectional force according to the dry shrinkage amount Applying the expansion amount of the concrete member to the relationship and calculating the addition amount of the expansion material.

  According to this, it is possible to obtain a value that accurately corresponds to each characteristic of the concrete member to be added and the expansion material with respect to the addition amount of the expansion material, and thus avoids the influence of the drying shrinkage of the concrete with high accuracy. In addition, it is possible to design a structure that further improves workability and economy.

  Further, in the addition amount calculation step of the above-described ramen structure design method, the calculated addition amount of the expansion material is included within a reference range determined with respect to the construction quality of the addition of the expansion material, and in each pattern described above. A step of determining whether or not the result of the compressive strength test performed on the test concrete satisfies the material strength necessary for the concrete member, and as a result of the determination, the conditions are satisfied. A step of determining the calculated addition amount of the expansion material as a design value when it is determined that the expansion amount is determined.

  According to this, regarding the addition amount of the expansion material, both the construction accuracy when adding the expansion material to the concrete member (such as the uniform dispersibility in the addition destination concrete and the control accuracy of the expansion amount) and the member strength after the addition of the expansion material It is possible to obtain a value that can achieve a good state, and consequently avoid the effects of drying shrinkage of the concrete with good precision, taking into account the construction accuracy of the expansion material and the strength of the member after the addition of the expansion material, workability and economic efficiency Therefore, it is possible to design a structure in which is improved.

  ADVANTAGE OF THE INVENTION According to this invention, the influence by the drying shrinkage | contraction of concrete can be avoided and the design of the structure from which workability and economical efficiency become favorable is attained.

It is a figure which shows the process example of the ramen structure design method in 1st Embodiment. It is a front view which shows the example of the rigid frame structure to which the rigid frame structure design method of 1st Embodiment is applied. It is a side view which shows the example of the ramen structure to which the ramen structure design method of 1st Embodiment is applied. It is a top view which shows the example of the rigid frame structure to which the rigid frame structure design method of 1st Embodiment is applied. It is a figure which shows the example of the correspondence of the expansion material addition amount and expansion amount in 1st Embodiment. It is a figure which shows the process example of the ramen structure design method in 2nd Embodiment.

--- First Embodiment ---
A first embodiment of the present invention will be described below in detail with reference to the drawings. Drawing 1 is a figure showing an example of a process of a frame structure design method in a 1st embodiment. 2 to 4 are a front view, a side view, and a plan view showing an example of the ramen structure 100 to which the ramen structure design method of the first embodiment is applied.

  In the first embodiment, a bridge 100 is shown as an example of a frame structure to which the frame structure design method is applied. As shown in FIGS. 2 to 4, the bridge 100 includes the bridge pier 10 and the superstructure 30 such as the girder 20 and the main girder 21, the floor slab 22, etc. that connect between the pier 10 and the stress of the pier 10 on the ground 1. It is mainly composed of a transmission base 40. Depending on the span length of the bridge pier 10, that is, the length of the beam member 20, the amount of drying shrinkage that occurs in the beam member 20 also increases. Such drying shrinkage in the girder 20 exerts a large bending stress on the pier 10 or the like to which the girder 20 is rigidly coupled.

Therefore, in the ramen structure design method according to the first embodiment, first, a basic design related to the bridge 100 such as the shape dimension and the material strength of the member to be used is executed (s100), and then the drying shrinkage of the bridge member 20 in the bridge 100 is performed. The amount is determined (s101). For the determination of the amount of drying shrinkage, an appropriate specified value for the amount of drying shrinkage according to the construction form of the bridge 100 and the like is selected from the specifications concerning the bridge. For example, according to the Road Bridge Specification (Japan Highway Association), the dry shrinkage of concrete is “150 × 10 ⁻⁶ ” for the construction mode when there is no change in the structural system during construction and after construction. There is a rule to do.

Subsequently, based on the dry shrinkage specified as described above, a target expansion amount in the girder 20 for suppressing this is determined (s102). The amount by which the girder 20 is expanded by the expansion material and cancels the drying shrinkage is the target expansion amount. For the determination of the target expansion amount, for example, a value that satisfies the target expansion amount to the maximum is selected within the standard range of the expansion coefficient related to the shrinkage compensation concrete indicated by the concrete standard specification (Japan Society of Civil Engineers). According to the specification of the concrete standard specification, the standard range of the expansion rate for the shrinkage compensation concrete is defined as “150 × 10 ⁻⁶ to 250 × 10 ⁻⁶ ”, and the drying shrinkage specified in the above-described step s101. “150 × 10 ⁻⁶ ” can be used as it is.

  Next, the expansion material is added in multiple patterns to the test concrete with the same specifications (aggregate, cement, water, etc., each component composition and admixture), and each pattern is added. Based on the test result obtained by measuring the expansion amount of the test concrete at, the relationship between the expansion material addition amount and the expansion amount in the girder 20 is calculated (s103). In addition, the concrete for a test at the time of expansion | swelling material addition is concrete before complete hardening, and mainly ready-mixed concrete. On the other hand, the concrete for a test at the time of measuring the amount of expansion corresponds to, for example, concrete having an age of 7 days.

In the first embodiment, expansion material is added in three types of addition amounts of 10 kg / m ³ , 12 kg / m ³ , and 15 kg / m ³ to the test concrete, and the test concrete at each addition amount is added. Was measured at each material age of 1, 2, 7 and 14 days. The measurement results are as shown by the measured values 501 to 512 in the graph 500 of FIG. According to the graph 500, it is apparent that the expansion amount gradually increases as the expansion material addition amount increases, and the increase in the expansion amount stops after a certain addition amount at any age. Moreover, even if it is the same expansion | swelling material addition amount, it turns out that the expansion | swelling amount tends to be large, so that material age is late.

  In calculating the relationship between the above-mentioned expansion material addition amount and expansion amount in the step s103, the measurement values 507 to 509 are referred to with reference to the measurement values 507 to 509 of the material age 7 based on the provisions of the concrete standard specifications. Formulas connecting ˜509 with line segments are calculated by a predetermined algorithm. The mathematical formula obtained here is a mathematical formula that defines the correspondence between the expansion material addition amount and the expansion amount.

Subsequently, the target expansion amount determined in step s102 is input to the mathematical formula obtained in step s103, and the expansion material addition amount into the concrete of the beam 20 to obtain the target expansion amount is calculated (s104). . In the example of the graph 500 in FIG. 5, when “150 × 10 ⁻⁶ ” is input as the target expansion amount, the addition amount of the expansion material can be calculated as “8 kg / m ³ ”. In addition, when the calculated addition amount of the expansion material falls below the minimum addition amount specified by the expansion material manufacturer, the minimum value specified by the manufacturer may be adopted.

Subsequently, in step s105, the expansion material addition amount calculated in the above-described step s104 is collated with a reference range defined for the construction quality of the expansion material addition. This reference range is assumed to be between 10 kg / m ³ stipulated by the expansion material manufacturer and 20 kg / m ^3, which is standard in concrete standard specifications and manufacturer technical data. It should be noted that if the addition amount of the expansion material is less than 10 kg / m ³ , the expansion material is not uniform in the concrete to be added, and the degree of expansion may vary depending on the location, which is not preferable. Moreover, when the addition amount of an expansion | swelling material is increased more than 20 kg / m < ³ >, there exists a possibility of producing a strength fall in the concrete of addition object, and it is not suitable.

  Further, in step s105, a compressive strength test is appropriately performed on the test concrete with each addition amount shown in step s103, and the test result is compared with a material strength value required for the girders 20. The material strength necessary for the girder 20 has been determined in step s100. As a result of the processing of step s105, when the amount of expansion material calculated in step s104 is included in the reference range, and the compressive strength of the test concrete at each addition amount satisfies the required material strength ( (s106: OK), the addition amount of the expansion material calculated in step s104 is determined as a design value (s107). On the other hand, when the addition amount of the expansion material calculated in step s104 is not included in the reference range, or the compressive strength of the test concrete at each addition amount does not satisfy the required material strength (s106: NG), The process is returned to step s102, and re-executed from the determination of the target expansion amount.

  If the amount of the expansion material determined as the design value is added to the concrete of the girder 20, while achieving the necessary material strength in the girder 20, according to the amount of drying shrinkage due to the expansion material, The cross-sectional force at the pier 10 that is rigidly connected to the beam member 20 is reduced.

  In addition, when there is a premise that drying shrinkage in the beam 20 is completely suppressed by adding the expansion material to the concrete of the beam 20 described above, the beam is parallel to steps s101 to s107 in the above-described steps. It is assumed that a reinforcing bar calculation step (s120) for the pier 10 that is rigidly connected to the material 20 is executed.

  In this case, first, based on the basic design determined in the above-described step s100, various loads such as its own weight on the pier 10 and earth and water pressure acting from the outside, seismic force, and the amount of change in temperature are derived from the above-described drying shrinkage. Various loads other than the bending stress are determined (s121). This is because the drying shrinkage in the girder 20 is completely suppressed and the adverse effect of the drying shrinkage does not reach the pier 10. In addition, what is necessary is just to employ | adopt the existing design technique for the determination process of the load in this step s121.

  Next, the cross-sectional force generated when the various loads determined in step s121 act on the pier 10 is calculated (s122), and the amount of reinforcement that the pier 10 can withstand the cross-sectional force is calculated based on the corresponding cross-sectional force. (S123). Existing techniques may be adopted for each method of calculating the cross-sectional force and the amount of bar arrangement. In this way, the amount of bar arrangement at the pier 10 was appropriately suppressed after taking into account the effect of drying shrinkage suppression on the spar 20, that is, the effect of relaxing the static destabilizing force at the pier 10 coupled to the spar 20. You can design the structure. Therefore, it is possible to design a ramen structure that provides good workability and economical efficiency in the bar arrangement process.

  In addition, when there is no premise that the drying shrinkage in the beam 20 is completely suppressed by adding the expansion material to the concrete of the above-described beam material 20, the expansion material calculated in step s 104 is determined in the above-described determination of step s 106. Is added within the standard range, and if it can be determined that the compressive strength of the test concrete at each added amount satisfies the required material strength, it is suppressed by adding the expansion material at the added amount. The value of the bending stress applied to the pier 10 is calculated, and the calculated value of the bending stress is included in the load determined in step s121 described above. Subsequent processes are the same as steps s122 to s123 described above.

--- Second Embodiment ---
Subsequently, unlike the first embodiment, regarding the pier 10 in a state where reinforcement and concrete placement have already been completed, it corresponds to a situation where various loads such as the bending stress described above are applied beyond the initial assumption. A second embodiment will be described. In this case, the concrete cast as the pier 10 has already started to be hardened, and the reinforcement cannot be redone. Also in the second embodiment, it is assumed that the ramen structure to which the ramen structure design method is applied is the bridge 100. FIG. 6 is a diagram illustrating a process example of the frame structure design method according to the second embodiment.

  Therefore, first, the cross-sectional force generated in the pier 10 is calculated based on the load that has been found with respect to the pier 10 and exceeds the initial assumption (s200). In this way, the situation where the load exceeds the initial assumption includes, for example, the number of vehicles passing through the bridge 100 in addition to the situation such as a change in the assumed temperature condition and an increase in the amount of drying shrinkage in the girders 20 due to various specification changes. It is possible to envisage a situation in which the number of vehicles increased significantly from the initial assumption, or the proportion of large vehicles among the vehicles passing through the bridge 100 increased significantly from the initial assumption. The load caused by such a traveling vehicle or the like also includes a component that acts as a bending stress on the pier 10 as in the case of the above-described drying shrinkage.

  Subsequently, when the cross-sectional force calculated in step s200 described above is collated with a predetermined standard and the cross-sectional force does not exceed the predetermined standard (s201: OK), the load has increased from the initial assumption. It is determined that no problem will occur, and the subsequent processing is terminated. Note that the predetermined standard for collating the cross-sectional force corresponds to the proof stress that the pier 10 is provided with in the initial design.

  On the other hand, as a result of collating the cross-sectional force calculated in step s200 described above with a predetermined standard, if the cross-sectional force exceeds the predetermined standard (s201: NG), the pier for the unfinished girders 20 coupled to the pier 10 is described. The amount of the expansion material added to the girder 20 for suppressing the cross-sectional force acting on 10 is calculated (s201). For example, the addition amount of the expansion material that causes the expansion amount in the girder 20 to cause the bridge pier 10 to act on the bridge pier 10 to cancel the cross-sectional force exceeding the predetermined reference is calculated.

  In addition, also in the frame structure design method in the second embodiment, the steps s103 to s107 in the first embodiment are executed in the same manner.

  According to this, various loads such as bending stress described above are initially assumed for structures (for example, bridge piers and foundations) of ramen structures in which reinforcement and concrete placement have already been completed. Even if it turns out that it takes above, in order to suppress the cross-sectional force acting on the relevant structure, the expansion material to be added to the horizontal member (eg, the bridge girder part of the bridge) combined with the above structure The amount added can be determined. Therefore, additional reinforcement measures such as covering the outer periphery of the structure with a steel plate are not necessary, and work efficiency and cost deterioration can be avoided. In other words, it is possible to avoid the influence due to drying shrinkage of the concrete and to design a structure with good workability and economy.

  According to the present embodiment, it is possible to avoid the influence due to drying shrinkage of the concrete, and to design a structure with good workability and economy.

  As mentioned above, although embodiment of this invention was described concretely based on the embodiment, it is not limited to this and can be variously changed in the range which does not deviate from the summary.

1 Ground 10 Bridge pier 20 Girder 21 Main girder 22 Floor slab 30 Superstructure 40 Foundation 100 Bridge (ramen structure)

Claims (6)

A design method for a rigid frame structure comprising a plurality of structures and a concrete member erected between the structures,
Based on the amount of drying shrinkage in the concrete member, an addition amount calculating step for calculating the amount of expansion material added to the concrete member for suppressing the amount of drying shrinkage;
For the structure coupled to the concrete member, a reduced cross-sectional force is calculated according to the amount of suppression of drying shrinkage due to the addition of the expansion material, and bar arrangement relating to the structure is performed based on the reduced cross-sectional force. Reinforcement calculation process to calculate,
A method for designing a ramen structure, comprising: The addition amount calculating step includes:
Based on the test results obtained by adding the expansion material with the addition amount of a plurality of patterns to the test concrete having the same specifications as the concrete member, and measuring the expansion amount of the test concrete with the addition amount of each pattern. Calculating the relationship between the amount of expansion material added and the amount of expansion in the member;
Applying the expansion amount of the concrete member for suppressing the drying shrinkage amount to the relationship, and calculating the addition amount of the expansion material;
The frame structure design method according to claim 1, comprising: In the addition amount calculation step,
The calculated addition amount of the expansion material is included in the reference range defined for the construction quality of the expansion material addition, and the result of the compressive strength test performed on the test concrete in each pattern is A process for determining whether each material satisfies the required material strength as a concrete member;
As a result of the determination, when it is determined that the respective conditions are satisfied, a step of determining the calculated addition amount of the expanded material as a design value;
The frame structure design method according to claim 2, further comprising: A design method for a rigid frame structure comprising a plurality of structures and a concrete member erected between the structures,
Regarding the already constructed structure among the ramen structures, the sectional force generated under the predetermined conditions after the present is calculated, and if the calculated sectional force exceeds the predetermined standard, the unconstructed concrete which is combined with the structure A method for designing a ramen structure, comprising an addition amount calculating step of calculating an addition amount of an expansion material to the concrete member for suppressing the cross-sectional force with respect to the member. The addition amount calculating step includes:
Based on the test results obtained by adding the expansion material with the addition amount of a plurality of patterns to the test concrete having the same specifications as the concrete member, and measuring the expansion amount of the test concrete with the addition amount of each pattern. Calculating the relationship between the amount of expansion material added and the amount of expansion in the member;
Applying the expansion amount of the concrete member that suppresses the cross-sectional force according to the dry shrinkage amount to the relationship, and calculating the addition amount of the expansion material;
The frame structure design method according to claim 4, comprising: In the addition amount calculation step,
The calculated addition amount of the expansion material is included in the reference range defined for the construction quality of the expansion material addition, and the result of the compressive strength test performed on the test concrete in each pattern is A process for determining whether each material satisfies the required material strength as a concrete member;
As a result of the determination, when it is determined that the respective conditions are satisfied, a step of determining the calculated addition amount of the expanded material as a design value;
The frame structure design method according to claim 5, further comprising:

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