JP6659935B2 - Strength evaluation method for reinforced concrete structures and strength evaluation program - Google Patents
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- 239000011150 reinforced concrete Substances 0.000 title claims description 112
- 238000011156 evaluation Methods 0.000 title claims description 11
- 230000007797 corrosion Effects 0.000 claims description 253
- 238000005260 corrosion Methods 0.000 claims description 253
- 230000002787 reinforcement Effects 0.000 claims description 121
- 230000003014 reinforcing effect Effects 0.000 claims description 119
- 238000000034 method Methods 0.000 claims description 87
- 238000004364 calculation method Methods 0.000 claims description 76
- 238000005452 bending Methods 0.000 claims description 69
- 239000004567 concrete Substances 0.000 claims description 53
- 230000007704 transition Effects 0.000 claims description 24
- 238000012545 processing Methods 0.000 claims description 15
- 238000005259 measurement Methods 0.000 claims description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 20
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 10
- 238000009792 diffusion process Methods 0.000 description 8
- 238000005336 cracking Methods 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 238000010276 construction Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000007689 inspection Methods 0.000 description 4
- 230000002093 peripheral effect Effects 0.000 description 4
- 230000036962 time dependent Effects 0.000 description 3
- 238000013461 design Methods 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000001066 destructive effect Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005674 electromagnetic induction Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
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本願発明は、鉄筋コンクリート構造物の耐力評価に関するものであり、より具体的には、せん断補強筋と主筋の腐食量をもとに算出される曲げせん断耐力比に基づいて、鉄筋コンクリート構造物の耐力を評価する方法及びプログラムに関するものである。 The present invention relates to the evaluation of the strength of a reinforced concrete structure, and more specifically, based on the bending shear strength ratio calculated based on the amount of corrosion of the shear reinforcement and the main reinforcement, the strength of the reinforced concrete structure. It relates to an evaluation method and a program.
我が国で建設された鉄筋コンクリート構造物は、既に長い年月を経たものが多くなってきた。特に、東京オリンピックを目前にした昭和３０年代は、いわゆる建設ラッシュといわれ多くの鉄筋コンクリート構造物が構築されたが、これらの構造物も現在では５０年以上経過している。一般にコンクリートの耐久性は５０年とも１００年ともいわれるが、仮に５０年とすると、当時建設された鉄筋コンクリート構造物は相当に老朽化し、必要な耐力が失われていることも考えられる。実際、地方自治体を中心に近年実施された橋梁点検では、多くの鉄筋コンクリー構造物でひび割れ等の損傷が確認されている。 Many reinforced concrete structures constructed in Japan have already passed many years. In the 1950's, especially before the Tokyo Olympics, many reinforced concrete structures were constructed in what is called a construction rush, and these structures have now been over 50 years old. Generally, the durability of concrete is said to be 50 years or 100 years, but if it is assumed to be 50 years, the reinforced concrete structure constructed at that time may be considerably deteriorated, and the necessary strength may be lost. In fact, in recent bridge inspections conducted mainly by local governments, damages such as cracks have been confirmed in many reinforced concrete structures.
鉄筋コンクリートのひび割れは、乾燥収縮や、コンクリートの内外温度差、想定外の外力による耐力不足、アルカリ骨材反応といった材料に伴うもの、など様々な要因によって発生する。特に古い構造物では、経年により腐食した鉄筋が膨張し、これに伴ってコンクリートにひび割れが発生するケースが多く見られる。この場合、ひび割れが鉄筋まで貫通していることから、空気と水に曝された鉄筋はさらに腐食の速度が大きくなる。 Cracks in reinforced concrete are caused by various factors such as drying shrinkage, temperature difference between the inside and outside of concrete, insufficient strength due to unexpected external force, and materials accompanying alkali-aggregate reaction. Particularly in an old structure, there are many cases in which the corroded reinforcing bar expands with the passage of time and cracks are generated in the concrete. In this case, since the crack penetrates to the reinforcing bar, the reinforcing bar exposed to air and water has a higher corrosion rate.
鉄筋の腐食が進むと、コンクリートのひび割れ幅も大きくなり、鉄筋とコンクリートの劣化から鉄筋コンクリート構造物としての耐力も小さくなっていく。必要とされる耐力を失うと構造物としての力学的な目的を果たさないため、通常はその前に補修や補強といった対策工が施される。ところが、鉄筋コンクリート構造物としての耐力を正しく評価することは容易ではなく、ましてや供用中の構造物の場合は非破壊による調査・検査を条件とされることも多く、さらに耐力評価を難しいものとしている。鉄筋コンクリート構造物の耐力が評価できないと、対策工を行う時期やその実施内容を適切に計画することができず、ひいては構造物の長寿命化を図ることができなくなる。 As the corrosion of the reinforcing bars progresses, the crack width of the concrete also increases, and the strength of the reinforced concrete structure decreases due to the deterioration of the reinforcing bars and the concrete. If the required proof strength is lost, the mechanical purpose of the structure will not be fulfilled. Therefore, countermeasures such as repair and reinforcement are usually performed before that. However, it is not easy to correctly evaluate the strength of a reinforced concrete structure, and in the case of a structure currently in service, non-destructive surveys and inspections are often required, making it more difficult to evaluate the strength. . If the proof strength of the reinforced concrete structure cannot be evaluated, it is not possible to appropriately plan the timing of implementing countermeasures and the contents of the measures, and thus it is impossible to extend the life of the structure.
そこで、種々の情報から鉄筋コンクリート構造物の耐力を推定する技術がこれまでも提案されており、例えば特許文献１では、直接計測により、あるいは計算によって鉄筋の腐食量を求め、この鉄筋腐食量に基づいて鉄筋コンクリート構造物の耐力を推定する技術について提案している。 Therefore, a technique for estimating the strength of a reinforced concrete structure from various information has been proposed. For example, in Patent Document 1, the amount of corrosion of a reinforcing bar is obtained by direct measurement or calculation, and based on this amount of corrosion of the reinforcing bar. We propose a technique for estimating the strength of reinforced concrete structures.
ところで、一般的な鉄筋コンクリート構造物には、図８に示すように主筋とせん断補強筋が配置される。主筋は主に曲げモーメントにより生ずる引張力に対抗するもので、せん断補強筋は主にせん断力に対抗するものである。また、せん断補強筋は、図８のように主筋に直交する方向で、主筋を取り巻くように配置される。つまり、主筋よりもせん断補強筋の方がかぶり深さが小さく、しかもその役割から主筋よりもせん断補強筋の方が径（断面）が小さいことが多い。かぶり深さが小さいほど早く鉄筋の腐食が始まり、鉄筋径が小さいほど腐食に伴う残存鉄筋量は減少しやすいことから、主筋とせん断補強筋の経時的な腐食の進行の程度は相違する。したがって、鉄筋コンクリート構造物のせん断耐力がコンクリートと鉄筋（主筋及びせん断補強筋）の断面積に基づいて求められ、その曲げ耐力が主筋に基づいて求められることを考えれば、鉄筋コンクリート構造物のせん断耐力と曲げ耐力の経時的な劣化程度は異なるわけである。 By the way, in a general reinforced concrete structure, a main reinforcing bar and a shear reinforcing bar are arranged as shown in FIG. The main rebar mainly counters the tensile force generated by the bending moment, and the shear reinforcing bar mainly opposes the shear force. Further, the shear reinforcing bars are arranged so as to surround the main bars in a direction orthogonal to the main bars as shown in FIG. In other words, the shear reinforcement has a smaller cover depth than the main reinforcement, and moreover, due to its role, the shear reinforcement has a smaller diameter (cross section) than the main reinforcement in many cases. The smaller the cover depth, the sooner the corrosion of the rebar starts, and the smaller the rebar diameter is, the more the amount of the remaining rebar associated with the corrosion tends to decrease. Therefore, the degree of progress of the corrosion of the main rebar and the shear reinforcement over time is different. Therefore, considering that the shear strength of a reinforced concrete structure is determined based on the cross-sectional area of concrete and reinforcing bars (main reinforcing bars and shear reinforcing bars), and the bending strength is determined based on the main reinforcing bars, the shear strength of a reinforced concrete structure is considered. The degree of deterioration of the bending strength over time is different.
既述のとおり、構造物の長寿命化を図るためには対策工を行う時期等を適切に判断する必要があり、そのためには鉄筋コンクリート構造物の耐力を的確に評価しなければならない。主筋とせん断補強筋の経時的な腐食進行程度がそれぞれ異なることを考えれば、その時点における主筋の腐食量とせん断補強筋の腐食量はそれぞれ個別に推定し、そのうえで鉄筋コンクリート構造物の耐力を的確に評価することが求められる。ところが特許文献１をはじめこれまでは、主筋とせん断補強筋の腐食進行程度をそれぞれ別に考慮したうえで鉄筋コンクリート構造物の耐力を評価することがなかった。 As described above, in order to extend the life of the structure, it is necessary to appropriately judge when to take countermeasures, and for that purpose, it is necessary to accurately evaluate the strength of the reinforced concrete structure. Considering that the degree of progress of corrosion of the main reinforcement and the shear reinforcement over time is different from each other, the amount of corrosion of the main reinforcement and that of the shear reinforcement at that time are individually estimated, and then the strength of the reinforced concrete structure is accurately determined. Evaluation is required. However, up to now, Patent Literature 1 has not evaluated the proof strength of a reinforced concrete structure in consideration of the degree of corrosion progress of the main reinforcement and the shear reinforcement separately.
本願発明の課題は、従来技術が抱える問題を解決することであり、すなわち、主筋とせん断補強筋の腐食の進行程度を個別に推定し、さらに鉄筋コンクリート構造物のせん断耐力と曲げ耐力を考慮したうえで鉄筋コンクリート構造物の耐力を評価することができる耐力評価方法と耐力評価プログラムを提供することである。 The problem of the present invention is to solve the problems of the prior art, that is, individually estimating the degree of progress of corrosion of the main reinforcement and the shear reinforcement, and further considering the shear strength and bending strength of the reinforced concrete structure. It is an object of the present invention to provide a proof stress evaluation method and a proof stress evaluation program that can evaluate the proof stress of a reinforced concrete structure.
本願発明は、主筋とせん断補強筋の経時的な腐食進行程度の相違に注目し、鉄筋コンクリート構造物のせん断耐力と曲げ耐力を求めるとともに、これらにより算出された「曲げせん断耐力比」に基づいて鉄筋コンクリート構造物の耐力を評価する、という点に着目してなされたものであり、これまでにない発想に基づいて行われた発明である。 The present invention focuses on the difference in the degree of progress of corrosion with time of the main reinforcement and the shear reinforcement, determines the shear strength and the bending strength of the reinforced concrete structure, and calculates the reinforced concrete ratio based on the “bending shear strength ratio” calculated by these. The invention has been made with a focus on evaluating the proof stress of a structure, and is an invention made based on an unprecedented idea.
本願発明の鉄筋コンクリート構造物の耐力評価方法は、第１腐食量算出工程と、第２腐食量算出工程、第１残存鉄筋量算出工程、第２残存鉄筋量算出工程、せん断耐力算出工程、曲げ耐力算出工程、曲げせん断耐力比算出工程、耐力評価工程を備えた方法である。このうち第１腐食量算出工程では、鉄筋径とかぶり深さに基づいてせん断補強筋の腐食量を求め、第２腐食量算出工程では、鉄筋径とかぶり深さに基づいて主筋の腐食量を求め、第１残存鉄筋量算出工程では、第１腐食量算出工程で得られた腐食量に基づいてせん断補強筋の残存鉄筋量を求め、第２残存鉄筋量算出工程では、第２腐食量算出工程で得られた腐食量に基づいて主筋の残存鉄筋量を求める。また、せん断耐力算出工程では、第１残存鉄筋量算出工程及び第２残存鉄筋量算出工程で得られた主筋及びせん断補強筋の残存鉄筋量に基づいて、鉄筋コンクリートのせん断耐力を算出する。一方、曲げ耐力算出工程では、第２残存鉄筋量算出工程で得られた主筋の残存鉄筋量に基づいて、鉄筋コンクリートの曲げ耐力を算出する。そして、曲げせん断耐力比算出工程では、せん断耐力算出工程で得られた鉄筋コンクリートのせん断耐力と、曲げ耐力算出工程で得られた鉄筋コンクリートの曲げ耐力に基づいて鉄筋コンクリートの曲げせん断耐力比を求め、耐力評価工程では、曲げせん断耐力比算出工程で得られた鉄筋コンクリートの曲げせん断耐力比と、あらかじめ設定された閾値を比較することで鉄筋コンクリート構造物の耐力を判定する。 The method for evaluating the strength of a reinforced concrete structure according to the present invention includes a first corrosion amount calculation step, a second corrosion amount calculation step, a first residual reinforcement amount calculation step, a second residual reinforcement amount calculation step, a shear strength calculation step, and a bending resistance. This is a method including a calculating step, a bending shear strength ratio calculating step, and a proof stress evaluating step. In the first corrosion amount calculation step, the amount of corrosion of the shear reinforcement is determined based on the reinforcing bar diameter and the cover depth, and in the second corrosion amount calculation step, the corrosion amount of the main reinforcement is determined based on the reinforcing bar diameter and the cover depth. In the first remaining reinforcing bar amount calculating step, the remaining reinforcing bar amount of the shear reinforcement is determined based on the corrosion amount obtained in the first corrosion amount calculating step, and in the second remaining reinforcing bar amount calculating step, the second corrosion amount calculating step is performed. Based on the corrosion amount obtained in the process, the remaining reinforcing bar amount of the main bar is obtained. In the shear strength calculation step, the shear strength of the reinforced concrete is calculated based on the remaining reinforcement amounts of the main reinforcement and the shear reinforcement obtained in the first residual reinforcement amount calculation step and the second residual reinforcement amount calculation step. On the other hand, in the bending strength calculation step, the bending strength of the reinforced concrete is calculated based on the remaining reinforcement amount of the main reinforcement obtained in the second remaining reinforcement amount calculation step. In the bending shear strength ratio calculating step, the bending strength ratio of the reinforced concrete is calculated based on the shear strength of the reinforced concrete obtained in the shear strength calculating step and the bending strength of the reinforced concrete obtained in the bending strength calculating step. In the step, the strength of the reinforced concrete structure is determined by comparing the bending shear strength ratio of the reinforced concrete obtained in the bending shear strength ratio calculation step with a preset threshold value.
本願発明の鉄筋コンクリート構造物の耐力評価方法は、さらに第１腐食進行推移推定工程と第２腐食進行推移推定工程を備えた方法とすることもできる。この第１腐食進行推移推定工程では、時間の経過とせん断補強筋の腐食量との関係を「第１腐食進行推移」として推定し、第２腐食進行推移推定工程では、時間の経過と主筋の腐食量との関係を「第２腐食進行推移」として推定する。 The method for evaluating the strength of a reinforced concrete structure according to the present invention may be a method further including a first corrosion progress transition estimation step and a second corrosion progress transition estimation step. In the first corrosion progress transition estimation step, the relationship between the passage of time and the corrosion amount of the shear reinforcement is estimated as “first corrosion progress transition”, and in the second corrosion progress transition estimation step, the progress of time and the main reinforcement The relationship with the corrosion amount is estimated as “second corrosion progress transition”.
本願発明の鉄筋コンクリート構造物の耐力評価方法は、さらに第１ひび割れ腐食量算出工程と第２ひび割れ腐食量算出工程を備えた方法とすることもできる。この第１ひび割れ腐食量算出工程では、せん断補強筋のかぶり深さ及び鉄筋径とコンクリート強度を含む条件に基づいて計算を行うことで、せん断補強筋の腐食によってコンクリートのひび割れが発生する「第１ひび割れ発生時期」におけるせん断補強筋の腐食量を「第１ひび割れ腐食量」として求める。また、第２ひび割れ腐食量算出工程では、主筋のかぶり深さ及び鉄筋径とコンクリート強度を含む条件に基づいて計算を行うことで、主筋の腐食によってコンクリートのひび割れが発生する「第２ひび割れ発生時期」における主筋の腐食量を「第２ひび割れ腐食量」として求める。なお、第１腐食進行推移推定工程では、せん断補強筋の腐食が始まる「第１腐食開始時期」と第１ひび割れ発生時期、第１腐食開始時期から第１ひび割れ発生時期までの「第１ひび割れ前腐食速度」、第１ひび割れ発生時期以降の「第１ひび割れ後腐食速度」に基づいて第１腐食進行推移を推定する。そして、第２腐食進行推移推定工程では、主筋の腐食が始まる「第２腐食開始時期」と、第２ひび割れ発生時期、第２腐食開始時期から第２ひび割れ発生時期までの「第２ひび割れ前腐食速度」、第２ひび割れ発生時期以降の「第２ひび割れ後腐食速度」に基づいて第２腐食進行推移を推定する。第１ひび割れ発生時期は、第１ひび割れ腐食速度と第１ひび割れ腐食量に基づいて求められ、第２ひび割れ発生時期は、第２ひび割れ前腐食速度と第２ひび割れ腐食量に基づいて求められる。 The method for evaluating the strength of a reinforced concrete structure according to the present invention may be a method further comprising a first crack corrosion amount calculation step and a second crack corrosion amount calculation step. In the first crack corrosion amount calculation step, the concrete is cracked due to corrosion of the shear reinforcement by performing calculations based on the conditions including the cover depth of the shear reinforcement, the reinforcing bar diameter, and the concrete strength. The amount of corrosion of the shear reinforcement at the “crack occurrence time” is determined as “first crack corrosion amount”. In the second crack corrosion amount calculation step, the calculation is performed based on the conditions including the cover depth of the main reinforcing bar, the diameter of the reinforcing bar, and the concrete strength, so that the cracking of the concrete occurs due to the corrosion of the main reinforcing bar. Is determined as the "second crack corrosion amount". In the first corrosion progress transition estimation step, the “first corrosion start time” at which the shear reinforcement starts to corrode and the first crack occurrence time, and the “first corrosion start time to the first crack occurrence time” from the first corrosion start time to the first crack occurrence time. The first corrosion progress transition is estimated based on the "corrosion rate" and the "post-crack corrosion rate" after the first crack generation time. Then, in the second corrosion progress transition estimation step, the “second corrosion start time” at which the main rebar starts to corrode, the second crack occurrence time, and the “second corrosion before corrosion” from the second corrosion start time to the second crack occurrence time. The second corrosion progress transition is estimated based on the “speed” and the “corrosion rate after the second crack” after the second crack generation time. The first crack occurrence time is obtained based on the first crack corrosion rate and the first crack corrosion amount, and the second crack generation time is obtained based on the second pre-crack corrosion rate and the second crack corrosion amount.
本願発明の鉄筋コンクリート構造物の耐力評価方法は、第１ひび割れ腐食量算出工程と第２ひび割れ腐食量算出工程において、せん断補強筋や主筋のうちコンクリート表面側の略半周面が腐食する条件で計算を行う方法とすることもできる。 In the method for evaluating the strength of a reinforced concrete structure according to the present invention, in the first crack corrosion amount calculation step and the second crack corrosion amount calculation step, the calculation is performed under the condition that substantially half the circumferential surface on the concrete surface side of the shear reinforcement and main reinforcement corrodes. It can also be a method of performing.
本願発明の鉄筋コンクリート構造物の耐力評価方法は、さらに寿命予測工程を備えた方法とすることもできる。この寿命予測工程では、第１腐食進行推移に基づいて求められるせん断補強筋の腐食量と、第２腐食進行推移に基づいて求められる主筋の腐食量を用いて、鉄筋コンクリートの曲げせん断耐力比が閾値を下回る時期を推定することで、鉄筋コンクリート構造物の寿命を予測する。 The method for evaluating the strength of a reinforced concrete structure according to the present invention may be a method further including a life prediction step. In this life prediction process, the flexural shear strength ratio of reinforced concrete is set to a threshold value using the corrosion amount of the shear reinforcement determined based on the first corrosion progression and the corrosion amount of the main reinforcement determined based on the second corrosion progression. By estimating the period of time below, the life of the reinforced concrete structure is predicted.
本願発明の鉄筋コンクリート構造物の耐力評価方法は、第１腐食量算出工程と第２腐食量算出工程において、第１腐食進行推移や第２腐食進行推移に基づいてせん断補強筋や主筋の腐食量を求める方法とすることもできる。 In the method for evaluating the strength of a reinforced concrete structure according to the present invention, in the first corrosion amount calculation step and the second corrosion amount calculation step, the corrosion amount of the shear reinforcement and the main reinforcement is determined based on the first corrosion progression and the second corrosion progression. It can also be the method of finding.
本願発明の鉄筋コンクリート構造物の耐力評価方法は、さらに第１ひび割れ幅計測工程と第２ひび割れ幅計測工程を備えた方法とすることもできる。この第１ひび割れ幅計測工程では、せん断補強筋の腐食によって生じたコンクリートのひび割れ幅を測定し、第２ひび割れ幅計測工程では、主筋の腐食によって生じたコンクリートのひび割れ幅を測定する。この場合、第１腐食量算出工程と第２腐食量算出工程では、第１ひび割れ幅計測工程や第２ひび割れ幅計測工程で得られたひび割れ幅と、せん断補強筋のかぶり深さ及び鉄筋径を含む推定式によって、せん断補強筋や主筋の腐食量を求める。 The method for evaluating the strength of a reinforced concrete structure according to the present invention may be a method further including a first crack width measuring step and a second crack width measuring step. In the first crack width measuring step, the crack width of concrete caused by corrosion of the shear reinforcement is measured, and in the second crack width measuring step, the crack width of concrete caused by corrosion of the main reinforcement is measured. In this case, in the first corrosion amount calculation step and the second corrosion amount calculation step, the crack width obtained in the first crack width measurement step and the second crack width measurement step, and the covering depth and the reinforcing bar diameter of the shear reinforcement are determined. The amount of corrosion of the shear reinforcement and the main reinforcement is determined by the estimation formulas including.
本願発明の鉄筋コンクリート構造物の耐力評価プログラムは、第１腐食量算出処理と、第２腐食量算出処理、第１残存鉄筋量算出処理、第２残存鉄筋量算出処理、せん断耐力算出処理、曲げ耐力算出処理、曲げせん断耐力比算出処理、耐力評価処理を、コンピュータに実行させる機能を備えたものである。このうち第１腐食量算出処理では、せん断補強筋の鉄筋径とかぶり深さの情報を読み出すとともに、この情報に基づいてせん断補強筋の腐食量を求め、第２腐食量算出処理では、主筋の鉄筋径とかぶり深さの情報を読み出すとともに、この情報に基づいて主筋の腐食量を求める。また、第１残存鉄筋量算出処理では、第１腐食量算出処理で得られた腐食量に基づいてせん断補強筋の残存鉄筋量を求め、第２残存鉄筋量算出処理では、第２腐食量算出処理で得られた腐食量に基づいて主筋の残存鉄筋量を求める。せん断耐力算出処理では、第１残存鉄筋量算出処理及び第２残存鉄筋量算出処理で得られた主筋及びせん断補強筋の残存鉄筋量に基づいて、鉄筋コンクリートのせん断耐力を算出する。一方、曲げ耐力算出処理では、第２残存鉄筋量算出処理で得られた主筋の残存鉄筋量に基づいて、鉄筋コンクリートの曲げ耐力を算出する。そして、曲げせん断耐力比算出処理では、せん断耐力算出処理で得られた鉄筋コンクリートのせん断耐力と、曲げ耐力算出処理で得られた鉄筋コンクリートの曲げ耐力に基づいて鉄筋コンクリートの曲げせん断耐力比を求め、耐力評価処理では、曲げせん断耐力比算出処理で得られた鉄筋コンクリートの曲げせん断耐力比と、あらかじめ設定された閾値を比較することで鉄筋コンクリート構造物の耐力を判定する。 The proof strength evaluation program for a reinforced concrete structure according to the present invention includes a first corrosion amount calculation process, a second corrosion amount calculation process, a first remaining reinforcement amount calculation process, a second remaining reinforcement amount calculation process, a shear strength calculation process, and a bending strength. It has a function of causing a computer to execute calculation processing, bending shear strength ratio calculation processing, and proof stress evaluation processing. In the first corrosion amount calculation processing, the information of the reinforcing bar diameter and the cover depth of the shear reinforcement is read, and the corrosion amount of the shear reinforcement is determined based on this information. Information on the rebar diameter and the depth of the cover is read out, and the amount of corrosion of the main rebar is obtained based on this information. Further, in the first remaining reinforcing bar amount calculating process, the remaining reinforcing bar amount of the shear reinforcement is obtained based on the corrosion amount obtained in the first corrosion amount calculating process, and in the second remaining reinforcing bar amount calculating process, the second corrosion amount calculating process is performed. Based on the amount of corrosion obtained in the treatment, the amount of remaining reinforcing steel in the main bar is determined. In the shear strength calculation processing, the shear strength of the reinforced concrete is calculated based on the remaining reinforcement amounts of the main reinforcement and the shear reinforcement obtained in the first residual reinforcement amount calculation processing and the second residual reinforcement amount calculation processing. On the other hand, in the bending strength calculation process, the bending strength of the reinforced concrete is calculated based on the remaining reinforcing bar amount of the main bar obtained in the second remaining reinforcing bar amount calculating process. In the bending shear strength ratio calculation process, the bending strength ratio of the reinforced concrete is obtained based on the shear strength of the reinforced concrete obtained in the shear strength calculation process and the bending strength of the reinforced concrete obtained in the bending strength calculation process. In the processing, the strength of the reinforced concrete structure is determined by comparing the bending shear strength ratio of the reinforced concrete obtained in the bending shear strength ratio calculation process with a preset threshold value.
本願発明の鉄筋コンクリート構造物の耐力評価方法、及び耐力評価プログラムには、次のような効果がある。
（１）主筋とせん断補強筋それぞれの腐食の進行程度を個別に評価することから、現実の構造物耐力を的確に判定することができる。特に、主筋よりもせん断補強筋が先行して腐食する状況を正しく評価する点で、従来に比してより高い信頼度で判定することができる。
（２）鉄筋コンクリート構造物に必要な補修や補強の内容や実施時期、あるいは建替えの要否などの判断に有用な情報を提供することができる。
The method for evaluating the strength of a reinforced concrete structure and the program for evaluating the strength of the present invention have the following effects.
(1) Since the degree of progress of corrosion of the main reinforcement and the shear reinforcement is individually evaluated, the actual structural strength can be accurately determined. In particular, in terms of correctly evaluating the situation in which the shear reinforcement corrodes ahead of the main reinforcement, the determination can be made with higher reliability than in the past.
(2) It is possible to provide useful information for determining the content and time of repair or reinforcement required for a reinforced concrete structure, or the necessity of rebuilding.
本願発明の鉄筋コンクリート構造物の耐力評価方法、及び耐力評価プログラムの実施形態の一例を、図に基づいて説明する。 An example of an embodiment of a reinforced concrete structure strength evaluation method and a strength evaluation program of the present invention will be described with reference to the drawings.
１．鉄筋の腐食
既述のとおり、本願発明は主筋とせん断補強筋の経時的な腐食進行の相違に注目したうえで鉄筋コンクリート構造物の耐力を評価する、という技術的特徴を備えている。そこで、まずは時間の経過とともに進行する鉄筋の腐食について説明する。
1. Corrosion of Reinforcing Bars As described above, the present invention has the technical feature of evaluating the proof strength of a reinforced concrete structure while paying attention to the difference in the progress of corrosion with time of the main reinforcing bar and the shear reinforcing bar. Therefore, first, the corrosion of the reinforcing steel that progresses with time will be described.
鉄筋の腐食は、コンクリート表面から侵入する塩化物イオンが徐々に拡散し、腐食する程度の量の塩化物イオンが鉄筋まで到達した時点で始まることが知られている。塩化物イオンの拡散が進むと、鉄筋周辺の塩化物イオン濃度が上昇していき、これに伴って鉄筋の腐食は進行していく。そして、鉄筋の腐食がさらに進行していくと鉄筋は膨張しはじめ、ある程度膨張するとコンクリートには引張力が作用し、遂にはコンクリートにひび割れが発生する。図１は、塩化物イオンの侵入からコンクリートのひび割れ発生までの各状態を示すモデル図であり、（ａ）は塩化物イオンがコンクリート表面から侵入する状態を、（ｂ）は鉄筋が腐食している状態を、（ｃ）は鉄筋の腐食によりコンクリートにひび割れが生じた状態を、それぞれ示している。 It is known that corrosion of reinforcing bars starts when chloride ions intruding from the concrete surface gradually diffuse and a sufficient amount of chloride ions reach the reinforcing bars. As the diffusion of chloride ions progresses, the chloride ion concentration around the reinforcing bar increases, and with this, corrosion of the reinforcing bar proceeds. Then, as the corrosion of the rebar further progresses, the rebar starts to expand, and when expanded to some extent, tensile force acts on the concrete, and finally the concrete cracks. FIG. 1 is a model diagram showing each state from the intrusion of chloride ions to the occurrence of cracks in concrete. FIG. 1 (a) shows the state in which chloride ions intrude from the concrete surface, and FIG. (C) shows a state in which concrete is cracked due to corrosion of a reinforcing bar.
また、鉄筋の腐食はほぼ一定の速度で進行することが知られている。ただし、ひび割れが発生した後は、ひび割れが鉄筋まで貫通していることから空気と水に曝される鉄筋が腐食する速度は大きくなる。図２は、鉄筋コンクリート構造物の経過時間（建設後の年数）と、鉄筋の腐食の程度の関係を示すグラフ図である。この図に示すように、鉄筋コンクリート構造物の建設後しばらくの期間、鉄筋は腐食しないが（図１（ａ）の状態）、ある時期から鉄筋の腐食が始まり、一定の速度で腐食が進行していく（図１（ｂ）の状態）。そしてコンクリートにひび割れが発生すると（図１（ｃ）の状態）、より大きな速度でさらに鉄筋の腐食が進行していく。なお、図２に示す「経過の時間と、鉄筋の腐食の程度との関係」を、ここでは便宜上「腐食進行推移」ということとする。 It is also known that corrosion of reinforcing bars proceeds at a substantially constant speed. However, after the crack occurs, the rate at which the reinforcing bar exposed to air and water corrodes increases because the crack penetrates to the reinforcing bar. FIG. 2 is a graph showing the relationship between the elapsed time (years after construction) of a reinforced concrete structure and the degree of corrosion of a reinforcing bar. As shown in this figure, the rebar does not corrode for a while after the construction of the reinforced concrete structure (the state shown in FIG. 1A), but the rebar starts to corrode at a certain time and progresses at a constant rate. (The state of FIG. 1B). When cracks occur in the concrete (the state shown in FIG. 1 (c)), corrosion of the reinforcing steel further proceeds at a higher speed. The “relationship between the elapsed time and the degree of corrosion of the reinforcing steel” shown in FIG. 2 is referred to as “corrosion progress transition” for convenience.
腐食進行推移を推定する手法について、図３を参照しながら詳しく説明する。図３は、腐食進行推移を推定する主要な工程の流れを示すフロー図である。従来から知られている塩化物拡散方程式を用い、鉄筋のかぶり深さと経過時間を入力値として、その時点におけるコンクリート内の塩化物イオン濃度分布を算出する。そして、経過時間を変えて繰り返し計算することにより、「塩化物イオン濃度分布の経時変化」を得る（Ｓｔｅｐ１０１）。ここで塩化物拡散方程式は、「コンクリート標準示方書―設計編―（土木学会）」に示される拡散係数と、コンクリート表面の塩化物イオン濃度、鉄筋コンクリート構造物の経過時間に基づく推定式である。なお、塩化物イオン濃度の実績値がある場合は、Ｆｉｃｋの法則に従う１次元拡散方程式を用いて得られた複数の値から、最小二乗法によって拡散係数を求めてもよい。 The method of estimating the progress of corrosion progress will be described in detail with reference to FIG. FIG. 3 is a flowchart showing the flow of the main steps for estimating the progress of corrosion progress. The chloride ion concentration distribution in the concrete at that time is calculated using the conventionally known chloride diffusion equation with the depth of the reinforcing bar and the elapsed time as input values. Then, by repeatedly performing the calculation while changing the elapsed time, a “time-dependent change in the chloride ion concentration distribution” is obtained (Step 101). Here, the chloride diffusion equation is an estimation equation based on the diffusion coefficient shown in “Specification Standard for Concrete—Design Edition— (Japan Society of Civil Engineers)”, the chloride ion concentration on the concrete surface, and the elapsed time of the reinforced concrete structure. If there is an actual value of the chloride ion concentration, the diffusion coefficient may be obtained by a least square method from a plurality of values obtained by using a one-dimensional diffusion equation according to Fick's law.
塩化物イオン濃度分布の経時変化が得られると、鉄筋が腐食を始める塩化物イオン濃度（限界塩化物イオン濃度）と照らして、鉄筋の腐食が開始する時期（以下、「腐食開始時期」という。）を求める（Ｓｔｅｐ１０２）。また、鉄筋が腐食する速度も推定する（Ｓｔｅｐ１０３）。このとき、先に説明したとおりひび割れ発生前と発生後ではその速度が変化するため、ひび割れ発生前の速度を「ひび割れ発生前腐食速度」として、ひび割れ発生後の速度を「ひび割れ発生後腐食速度」として推定する。この推定を行うにあたっては、従来から用いられている推定速度値を利用することもできるし、実験や解析（シミュレーション）等によって得られた速度値を用いてもよい。なお、腐食速度としては、腐食断面積に着目した速度（つまり、単位時間当たりの質量や面積）としてもよいし、鉄筋の半径（直径）方向の減少に着目した速度（つまり、単位時間当たりの長さ）としてもよいし、質量（面積）や長さの比率に着目した速度としてもよい。 When a change with time of the chloride ion concentration distribution is obtained, the time at which the corrosion of the reinforcing bar starts (hereinafter, referred to as “corrosion start time”) in light of the chloride ion concentration at which the reinforcing bar starts to corrode (limit chloride ion concentration). ) Is obtained (Step 102). Further, the rate at which the reinforcing steel corrodes is also estimated (Step 103). At this time, as described above, since the speed changes before and after the occurrence of cracking, the speed before cracking is defined as “corrosion rate before cracking”, and the speed after cracking is defined as “corrosion rate after cracking”. Is estimated as In performing this estimation, a conventionally used estimated speed value may be used, or a speed value obtained by an experiment, analysis (simulation), or the like may be used. The corrosion rate may be a rate focused on the corrosion cross-sectional area (that is, mass or area per unit time), or a rate focused on a decrease in the radius (diameter) direction of the reinforcing bar (that is, a rate per unit time). Length) or a speed focusing on the ratio of mass (area) or length.
次に、ひび割れが発生する時期（以下、「ひび割れ発生時期」という。）を求めるため、コンクリートにひび割れが発生する程度の膨張量に基づいて、鉄筋の腐食量を算出する（Ｓｔｅｐ１０４）。なお、ひび割れ発生時期における鉄筋の腐食量を、ここでは便宜上、「ひび割れ腐食量」ということとする。このひび割れ腐食量は、例えば、コンクリート強度や、鉄筋のかぶり深さ、鉄筋径などを入力値として、ＦＥＭ（Ｆｉｎｉｔｅ Ｅｌｅｍｅｎｔ Ｍｅｔｈｏｄ）解析によって算出することかができる。本願発明者らは、コンクリート強度ｆｃを１８Ｎ／ｍｍ２とし、鉄筋径をＤ１６，Ｄ２５，Ｄ３２、鉄筋のかぶり深さを４０ｍｍ，６０ｍｍ，８０ｍｍ，１００ｍｍとしてＦＥＭ解析を行い、ひび割れ腐食量を求めた。図４はその結果を示すグラフ図である。なお、図４（ａ）は鉄筋の全周面が一様に腐食するという条件で、（ｂ）は鉄筋表面のうちコンクリート表面側の略半周面（半周面含む）が腐食するという条件でＦＥＭ解析を行った結果である。 Next, in order to determine the time at which a crack occurs (hereinafter, referred to as "crack occurrence time"), the amount of corrosion of the reinforcing steel is calculated based on the amount of expansion at which cracks occur in concrete (Step 104). Here, the amount of corrosion of the reinforcing steel at the time of crack occurrence is referred to as “crack corrosion amount” for convenience. The crack corrosion amount can be calculated by, for example, FEM (Finite Element Method) analysis using the concrete strength, the reinforcing bar cover depth, the reinforcing bar diameter, and the like as input values. The present inventors performed FEM analysis by setting the concrete strength fc to 18 N / mm 2 , the reinforcing bar diameter to D16, D25, and D32, and the reinforcing bar cover depth to 40 mm, 60 mm, 80 mm, and 100 mm to obtain the amount of crack corrosion. . FIG. 4 is a graph showing the results. 4A shows the condition that the entire peripheral surface of the reinforcing bar is uniformly corroded, and FIG. 4B shows the FEM under the condition that the substantially half peripheral surface (including the half peripheral surface) of the reinforcing bar surface on the concrete surface side is corroded. This is the result of the analysis.
腐食開始時期と、ひび割れ発生前腐食速度、ひび割れ腐食量が得られると、ひび割れ発生時期を求めることができる（Ｓｔｅｐ１０５）。そして、ここまでで求めた腐食開始時期と、ひび割れ発生前腐食速度、ひび割れ発生時期、ひび割れ発生後腐食速度に基づいて、図２に示すような腐食進行推移を推定することができる（Ｓｔｅｐ１０６）。 When the corrosion start time, the pre-crack corrosion rate, and the amount of crack corrosion are obtained, the crack generation time can be determined (Step 105). Then, based on the corrosion start time thus obtained, the corrosion rate before crack occurrence, the crack occurrence time, and the corrosion rate after crack occurrence, it is possible to estimate a corrosion progress transition as shown in FIG. 2 (Step 106).
２．鉄筋コンクリート構造物の耐力評価方法
次に、本願発明の鉄筋コンクリート構造物の耐力評価方法について、図５を参照しながら説明する。図５は、本願発明の鉄筋コンクリート構造物の耐力評価方法の主要な工程の流れを示すフロー図である。
2. Next, a method for evaluating the strength of a reinforced concrete structure according to the present invention will be described with reference to FIG. FIG. 5 is a flowchart showing the flow of the main steps of the method for evaluating the strength of a reinforced concrete structure according to the present invention.
（せん断補強筋の腐食量）
本願発明では、鉄筋コンクリートの曲げ耐力とせん断耐力の比である「曲げせん断耐力比」を求めることから、鉄筋コンクリートのせん断耐力、及び曲げ耐力をそれぞれ得る必要があり、そのためにはせん断補強筋の腐食量を算出し（第１腐食量算出工程：Ｓｔｅｐ２１１）、主筋の腐食量を算出する（第２腐食量算出工程：Ｓｔｅｐ２２１）必要がある。まずはせん断補強筋の腐食量の算出から詳しく説明する。
(Corrosion of shear reinforcement)
In the present invention, it is necessary to obtain the shear strength and the bending strength of the reinforced concrete, respectively, by obtaining the "bending shear strength ratio", which is the ratio of the bending strength and the shear strength of the reinforced concrete, and for that, the corrosion amount of the shear reinforcing bars (The first corrosion amount calculation step: Step 211), and the corrosion amount of the main bar must be calculated (the second corrosion amount calculation step: Step 221). First, the calculation of the amount of corrosion of the shear reinforcement will be described in detail.
せん断補強筋の腐食量を算出する手法としては、２種類の手法が挙げられる。１つ目は、せん断補強筋の腐食進行推移（以下、「第１腐食進行推移」という。）を利用する手法である。これまで図３に沿って説明した手順で第１腐食進行推移を推定し、現時点におけるせん断補強筋の腐食量を求めるわけである。具体的には、塩化物拡散方程式を用いてコンクリート内の塩化物イオン濃度分布の経時変化を得る（図３のＳｔｅｐ１０１）とともに、せん断補強筋の腐食が開始する時期（以下、「第１腐食開始時期」という。）を求め（図３のＳｔｅｐ１０２）、ひび割れ発生前の速度を「第１ひび割れ発生前腐食速度」として、ひび割れ発生後の速度を「第１ひび割れ発生後腐食速度」として推定する（図３のＳｔｅｐ１０３）。そして、コンクリートにひび割れが発生する際のせん断補強筋の腐食量（以下、「第１ひび割れ腐食量」という。）をＦＥＭ解析で算出し（図３のＳｔｅｐ１０４）、せん断補強筋が腐食したことによってコンクリートにひび割れが生じる時期（以下、「第１ひび割れ発生時期」という。）を求め、せん断補強筋の第１腐食進行推移を推定する（図３のＳｔｅｐ１０６）。
There are two types of methods for calculating the amount of corrosion of the shear reinforcement. The first is a technique that utilizes the progress of corrosion of the shear reinforcement (hereinafter, referred to as “first corrosion progress”). The progress of the first corrosion progress is estimated by the procedure described so far with reference to FIG. 3, and the corrosion amount of the shear reinforcement at the present time is obtained. Specifically, a time-dependent change in the chloride ion concentration distribution in the concrete is obtained using the chloride diffusion equation (
２つ目は、せん断補強筋が腐食したことによって生じたコンクリートのひび割れに基づいて、せん断補強筋の腐食量を求める手法である。したがってこの場合は、せん断補強筋の腐食によって生じたコンクリートのひび割れ幅を測定する（以下、「第１ひび割れ幅計測工程」という。）必要がある。図６は、測定したひび割れ幅に基づいて鉄筋腐食量を算出する流れを示すフロー図である。せん断補強筋が配置された位置が把握できれば、せん断補強筋の腐食に伴うひび割れを抽出することができるため、そのひび割れ幅を測定し、推定式を用いてせん断補強筋の腐食量を求める。なお、せん断補強筋の位置は、設計図や竣工図などの記録に基づいて把握するか、コンクリートの非破壊検査（例えば、電磁誘導法や電磁波レーダ法）によって把握することかできる。 The second is a method of calculating the amount of corrosion of the shear reinforcement based on cracks in concrete caused by corrosion of the shear reinforcement. Therefore, in this case, it is necessary to measure the crack width of the concrete caused by the corrosion of the shear reinforcement (hereinafter, referred to as “first crack width measuring step”). FIG. 6 is a flowchart showing the flow of calculating the amount of reinforcing steel corrosion based on the measured crack width. If the position where the shear reinforcement is arranged can be grasped, cracks due to corrosion of the shear reinforcement can be extracted. Therefore, the width of the crack is measured, and the amount of corrosion of the shear reinforcement is calculated using an estimation formula. In addition, the position of the shear reinforcement can be grasped based on records such as a design drawing and a completed drawing, or can be grasped by a nondestructive inspection of concrete (for example, an electromagnetic induction method or an electromagnetic wave radar method).
測定されたひび割れ幅に基づいて鉄筋の腐食量を推定するための推定式は、発明者らが多くの実績データに基づいて見出した下記の４つの式のうちいずれかを使用することができる。なお推定式中のｙは鉄筋の腐食量であり、ｔはひび割れ幅、ｃは鉄筋のかぶり深さ、ｄは鉄筋径である。また、αとβは定数で、複数の実績データから推定して求めることができる。
（主筋の腐食量）
主筋の腐食量を算出する手法も、せん断補強筋と同様、主筋の腐食進行推移（以下、「第２腐食進行推移」という。）を利用する手法と、現実に発生したひび割れに基づく手法の場合がある。第２腐食進行推移を利用する手法の場合、第２腐食進行推移を推定し、現時点における主筋の腐食量を求める。具体的には、塩化物拡散方程式を用いてコンクリート内の塩化物イオン濃度分布の経時変化を得る（図３のＳｔｅｐ１０１）とともに、主筋の腐食が開始する時期（以下、「第２腐食開始時期」という。）を求め（図３のＳｔｅｐ１０２）、ひび割れ発生前の速度を「第２ひび割れ発生前腐食速度」として、ひび割れ発生後の速度を「第２ひび割れ発生後腐食速度」として推定する（図３のＳｔｅｐ１０３）。そして、コンクリートにひび割れが発生する際の主筋の腐食量（以下、「第２ひび割れ腐食量」という。）をＦＥＭ解析で算出し（図３のＳｔｅｐ１０４）、主筋が腐食したことによってコンクリートにひび割れが生じる時期（以下、「第２ひび割れ発生時期」という。）を求め、主筋の第２腐食進行推移を推定する（図３のＳｔｅｐ１０６）。
(Corrosion amount of main bar)
Similar to the shear reinforcement, the method of calculating the amount of corrosion of the main rebar is a method using the progress of corrosion of the main rebar (hereinafter, referred to as “second corrosion progress”) and a method based on a crack that has actually occurred. There is. In the case of the method using the second corrosion progress transition, the second corrosion progress transition is estimated, and the corrosion amount of the main bar at the present time is obtained. Specifically, a time-dependent change in the chloride ion concentration distribution in the concrete is obtained using the chloride diffusion equation (
現実に発生したひび割れに基づく手法の場合、主筋が腐食したことによって生じたコンクリートのひび割れに基づいて推定する。したがってこの場合は、主筋の腐食によって生じたコンクリートのひび割れ幅を測定する（以下、「第２ひび割れ幅計測工程」という。）必要がある（図６）。主筋の腐食量は、既述した推定式（式１−１〜式１−４）を用いて算出するとよい。なお主筋の場合も、配置された位置が把握できれば主筋の腐食に伴うひび割れを抽出することができる。主筋の位置は、設計図や竣工図などの記録、あるいはコンクリートの非破壊検査によって把握する。 In the case of a method based on cracks actually occurring, the estimation is performed based on cracks in concrete caused by corrosion of the main reinforcement. Therefore, in this case, it is necessary to measure the crack width of the concrete caused by corrosion of the main bar (hereinafter, referred to as “second crack width measuring step”) (FIG. 6). The amount of corrosion of the main bar may be calculated using the above-described estimation formulas (Formula 1-1 to Formula 1-4). In the case of the main reinforcement as well, if the location of the main reinforcement can be grasped, cracks due to corrosion of the main reinforcement can be extracted. The location of the main reinforcement is ascertained by records such as blueprints and completed drawings, or by nondestructive inspection of concrete.
（せん断耐力）
鉄筋コンクリートのせん断耐力は、コンクリートと鉄筋の断面積により定められる。コンクリートは、一般的に時間の経過に伴い断面積は変化しないとされるが、鉄筋は腐食するため時間の経過に伴い断面積は減少していく。なおせん断耐力に寄与する鉄筋は、せん断補強筋と主筋の両方である。そこで、せん断補強筋の腐食量からせん断補強筋の残存鉄筋量を算出し（第１残存鉄筋量算出工程：Ｓｔｅｐ２１２）、主筋の腐食量から主筋の残存鉄筋量を算出して（第２残存鉄筋量算出工程：Ｓｔｅｐ２２２）、これらせん断補強筋の残存鉄筋量と、主筋の残存鉄筋量、コンクリート断面に基づいて鉄筋コンクリートのせん断耐力を算出する（せん断耐力算出工程：Ｓｔｅｐ２１３）。
(Shear strength)
The shear strength of reinforced concrete is determined by the cross-sectional area of concrete and reinforcing steel. It is generally assumed that the cross-sectional area of concrete does not change with time, but the cross-sectional area decreases with time due to corrosion of reinforcing steel. The reinforcing bars that contribute to the shear strength are both the shear reinforcing bars and the main bars. Therefore, the amount of residual reinforcing bar of the shear reinforcing bar is calculated from the amount of corrosion of the shear reinforcing bar (first remaining reinforcing bar amount calculating step: Step 212), and the amount of remaining reinforcing bar of the main bar is calculated from the amount of corrosion of the main reinforcing bar (second remaining reinforcing bar). Amount calculating step: Step 222), the shear strength of the reinforced concrete is calculated based on the remaining reinforcing bar amount of these shear reinforcing bars, the remaining reinforcing bar amount of the main reinforcing bar, and the concrete cross section (shear strength calculating step: Step 213).
（曲げ耐力）
鉄筋コンクリートの曲げ耐力は、主筋の鉄筋径や、降伏強度、かぶり深さにより定められる。つまり、曲げ耐力に寄与するのは主に主筋である。第２腐食量算出工程（Ｓｔｅｐ２２１）で主筋の腐食量が得られ、第２残存鉄筋量算出工程（Ｓｔｅｐ２２２）で主筋の残存鉄筋量が得られると、この主筋の残存鉄筋量に基づいて鉄筋コンクリートの曲げ耐力を算出する（曲げ耐力算出工程：Ｓｔｅｐ２２３）。
(Bending strength)
The bending strength of reinforced concrete is determined by the diameter of the reinforcing bar, yield strength, and cover depth. That is, it is the main reinforcement that mainly contributes to the bending strength. When the corrosion amount of the main reinforcement is obtained in the second corrosion amount calculation step (Step 221) and the residual reinforcement amount of the main reinforcement is obtained in the second residual reinforcement amount calculation step (Step 222), the reinforced concrete based on the residual reinforcement amount of the main reinforcement is obtained. The bending strength is calculated (bending strength calculation step: Step 223).
（曲げせん断耐力比）
鉄筋コンクリートのせん断耐力と曲げ耐力が求められると、せん断耐力を曲げ耐力で除した曲げせん断耐力比を求める（曲げせん断耐力比算出工程：Ｓｔｅｐ２３１）。図７は、鉄筋コンクリートの曲げせん断耐力比の時間変化を説明するグラフ図であり、（ａ）はせん断補強筋の腐食進行推移（第１腐食進行推移）と主筋の腐食進行推移（第２腐食進行推移）を示し、（ｂ）は時間の経過と曲げせん断耐力比の関係を示している。この図から分かるように、主筋よりもせん断補強筋の腐食の方が早く進行することから、主筋が腐食する時期（第２腐食開始時期）より前から曲げせん断耐力比は低減していき、せん断補強筋の腐食によるひび割れが生じる時期（第１ひび割れ発生時期）から急激に曲げせん断耐力比は低減する。
(Bending shear strength ratio)
When the shear strength and the bending strength of the reinforced concrete are obtained, a bending shear strength ratio is calculated by dividing the shear strength by the bending strength (bending shear strength ratio calculating step: Step 231). FIGS. 7A and 7B are graphs for explaining the change over time of the bending shear strength ratio of reinforced concrete. FIG. 7A shows the progress of corrosion progress of the shear reinforcement (first corrosion progress) and the progress of corrosion of the main reinforcement (second corrosion progress). (B) shows the relationship between the passage of time and the bending shear strength ratio. As can be seen from this figure, since the corrosion of the shear reinforcement progresses faster than the main reinforcement, the flexural shear strength ratio decreases before the time at which the main reinforcement corrodes (second corrosion start time), and the shear strength increases. The bending shear strength ratio sharply decreases from the time when cracks due to corrosion of reinforcing bars occur (the first crack generation time).
（耐力判定）
その時点における鉄筋コンクリートの曲げせん断耐力比が得られると、あらかじめ設定された閾値と照らし合わせ（Ｓｔｅｐ２３２）、鉄筋コンクリート構造物の耐力を判定する（耐力評価工程：Ｓｔｅｐ２３３）。例えば、図７（ｂ）に示すように２段階の閾値を設定し、曲げせん断耐力比が閾値１．５を下回ると「やや危険」と判断し、曲げせん断耐力比が閾値１．０を下回ると「危険」と判断することができる。また、図７（ｂ）と現時点を照らし合わせることで、鉄筋コンクリート構造物が「やや危険」となる時期や、「危険」となる時期を予測することができ、すなわち当該鉄筋コンクリート構造物の寿命予測を行うこともできる（寿命予測工程：Ｓｔｅｐ２３４）。
(Judgment of strength)
When the flexural-shear strength ratio of the reinforced concrete at that time is obtained, the strength of the reinforced concrete structure is determined by comparing it with a preset threshold (Step 232) (proof strength evaluation step: Step 233). For example, as shown in FIG. 7B, two threshold values are set, and when the bending shear strength ratio falls below the threshold value 1.5, it is determined to be “somewhat dangerous”, and the bending shear strength ratio falls below the threshold value 1.0. And "dangerous" can be determined. Further, by comparing FIG. 7 (b) with the present time, it is possible to predict the time when the reinforced concrete structure becomes “slightly dangerous” or the time when it becomes “dangerous”. That is, the life prediction of the reinforced concrete structure can be performed. This can also be performed (life prediction step: Step 234).
３．鉄筋コンクリート構造物の耐力評価プログラム
本願発明の鉄筋コンクリート構造物の耐力評価プログラムについて、図５を参照しながら説明する。なお、本願発明の鉄筋コンクリート構造物の耐力評価プログラムは、ここまで説明してきた内容で鉄筋コンクリート構造物の耐力を評価するプログラムであり、したがって「２．鉄筋コンクリート構造物の耐力評価方法」と重複する内容の説明は避け、鉄筋コンクリート構造物の耐力評価プログラムに特有の内容のみ説明することとする。すなわち、ここに記載されていない内容は、「２．鉄筋コンクリート構造物の耐力評価方法」で記載したものと同様である。
3. Program for Evaluating Strength of Reinforced Concrete Structure The program for evaluating strength of a reinforced concrete structure of the present invention will be described with reference to FIG. The reinforced concrete structure strength evaluation program of the present invention is a program for evaluating the strength of a reinforced concrete structure in the manner described above, and therefore has the same content as “2. Method for evaluating reinforced concrete structure strength”. Explanation will be avoided, and only the contents specific to the reinforced concrete structure strength evaluation program will be explained. That is, the contents not described here are the same as those described in “2. Evaluation method of proof strength of reinforced concrete structure”.
はじめに、記憶手段に記憶されたせん断補強筋の鉄筋径とかぶり深さの情報を読み出すとともに、せん断補強筋の腐食量を算出する処理（第１腐食量算出処理：Ｓｔｅｐ２１１）が実行される。あわせて、記憶手段に記憶された主筋の鉄筋径とかぶり深さの情報を読み出すとともに、主筋の腐食量を算出する処理（第２腐食量算出処理：Ｓｔｅｐ２２１）が実行される。そして、このせん断補強筋の腐食量からせん断補強筋の残存鉄筋量を算出する処理（第１残存鉄筋量算出処理：Ｓｔｅｐ２１２）が実行され、主筋の腐食量から主筋の残存鉄筋量を算出する処理（第２残存鉄筋量算出処理：Ｓｔｅｐ２２２）が実行される。これらせん断補強筋の残存鉄筋量と、主筋の残存鉄筋量、コンクリート断面に基づいて鉄筋コンクリートのせん断耐力を算出する処理（せん断耐力算出処理：Ｓｔｅｐ２１３）が実行される。 First, a process of reading out the information of the reinforcing bar diameter and the covering depth of the shear reinforcing bar stored in the storage means and calculating the corrosion amount of the shear reinforcing bar (first corrosion amount calculating process: Step 211) is executed. At the same time, the information of the reinforcing bar diameter and the fogging depth of the main bar stored in the storage means is read, and the process of calculating the amount of corrosion of the main bar (second corrosion amount calculating process: Step 221) is executed. Then, a process of calculating the remaining reinforcing bar amount of the shear reinforcing bar from the corrosion amount of the shear reinforcing bar (first remaining reinforcing bar amount calculating process: Step 212) is performed, and a process of calculating the remaining reinforcing bar volume of the main reinforcing bar from the corrosion amount of the main reinforcing bar. (Second remaining rebar amount calculation processing: Step 222) is executed. A process of calculating the shear strength of the reinforced concrete based on the remaining reinforcing bar amount of these shear reinforcing bars, the remaining reinforcing bar amount of the main bar, and the concrete section (shear strength calculating process: Step 213) is executed.
次に、第２残存鉄筋量算出処理（Ｓｔｅｐ２２２）で得られた主筋の残存鉄筋量に基づいて、鉄筋コンクリートの曲げ耐力を算出する処理（曲げ耐力算出処理：Ｓｔｅｐ２２３）が実行される。 Next, a process for calculating the bending strength of the reinforced concrete (bending strength calculation process: Step 223) is executed based on the remaining reinforcing bar amount of the main bar obtained in the second remaining reinforcing bar amount calculation process (Step 222).
鉄筋コンクリートのせん断耐力と曲げ耐力が求められると、せん断耐力を曲げ耐力で除した曲げせん断耐力比を求める処理（曲げせん断耐力比算出処理：Ｓｔｅｐ２３１）が実行される。そして、その時点における鉄筋コンクリートの曲げせん断耐力比が得られると、記憶手段から読み出された閾値と照らし合わせ（Ｓｔｅｐ２３２）、鉄筋コンクリート構造物の耐力を判定する処理（耐力評価処理：Ｓｔｅｐ２３３）が実行される。また、時間の経過と曲げせん断耐力比の関係（図７（ｂ））と現時点を照らし合わせることで、当該鉄筋コンクリート構造物の寿命予測を行う処理（寿命予測処理：Ｓｔｅｐ２３４）を実行することもできる。 When the shear strength and the bending strength of the reinforced concrete are obtained, a process of calculating a bending shear strength ratio by dividing the shear strength by the bending strength (bending shear strength ratio calculation process: Step 231) is executed. When the bending-shear strength ratio of the reinforced concrete at that time is obtained, the strength is checked against the threshold value read out from the storage means (Step 232), and the processing for determining the strength of the reinforced concrete structure (proof strength evaluation processing: Step 233) is executed. You. In addition, by comparing the relationship between the passage of time and the bending shear strength ratio (FIG. 7B) with the present time, a process of predicting the life of the reinforced concrete structure (life prediction process: Step 234) can also be executed. .
本願発明の鉄筋コンクリート構造物の耐力評価方法、及び耐力評価プログラムは、橋梁の下部工や、コンクリート擁壁、ボックスカルバートといった土木構造物、あるいはオフィスビル等の建築構造物、その他種々の鉄筋コンクリート構造物に利用することができる。本願発明が、補強等の実施内容や実施時期にとって有用な情報を提供し、すなわち鉄筋コンクリート構造物の長寿命化に資することを考えれば、産業上利用できるばかりでなく社会的にも大きな貢献を期待し得る発明といえる。 The method for evaluating the strength of a reinforced concrete structure of the present invention and the strength evaluation program are used for substructures of bridges, concrete retaining walls, civil structures such as box culverts, architectural structures such as office buildings, and various other reinforced concrete structures. Can be used. In view of the fact that the present invention provides useful information on the content and timing of implementation of reinforcement and the like, that is, contributing to extending the life of reinforced concrete structures, not only can it be used industrially, but it is also expected to make a significant contribution to society It can be said that the invention is possible.
Claims (8)
鉄筋径とかぶり深さに基づいて、せん断補強筋の腐食量を求める第１腐食量算出工程と、
鉄筋径とかぶり深さに基づいて、主筋の腐食量を求める第２腐食量算出工程と、
前記第１腐食量算出工程で得られた腐食量に基づいて、前記せん断補強筋の残存鉄筋量を求める第１残存鉄筋量算出工程と、
前記第２腐食量算出工程で得られた腐食量に基づいて、前記主筋の残存鉄筋量を求める第２残存鉄筋量算出工程と、
前記せん断補強筋及び前記主筋の残存鉄筋量に基づいて、鉄筋コンクリートのせん断耐力を算出するせん断耐力算出工程と、
前記主筋の残存鉄筋量に基づいて、鉄筋コンクリートの曲げ耐力を算出する曲げ耐力算出工程と、
前記せん断耐力算出工程で得られた鉄筋コンクリートのせん断耐力と、前記曲げ耐力算出工程で得られた鉄筋コンクリートの曲げ耐力と、に基づいて鉄筋コンクリートの曲げせん断耐力比を求める曲げせん断耐力比算出工程と、
前記曲げせん断耐力比算出工程で得られた鉄筋コンクリートの曲げせん断耐力比と、あらかじめ設定された閾値と、を比較することで前記鉄筋コンクリート構造物の耐力を判定する耐力評価工程と、
を備えた、ことを特徴とする鉄筋コンクリート構造物の耐力評価方法。 In a method for evaluating the strength of a reinforced concrete structure,
A first corrosion amount calculating step of calculating a corrosion amount of the shear reinforcing bar based on a reinforcing bar diameter and a covering depth;
A second corrosion amount calculating step of obtaining a corrosion amount of the main bar based on the rebar diameter and the cover depth;
A first remaining reinforcing bar amount calculating step of obtaining a remaining reinforcing bar amount of the shear reinforcement based on the corrosion amount obtained in the first corrosion amount calculating step;
A second remaining reinforcing bar amount calculating step of obtaining a remaining reinforcing bar amount of the main bar based on the corrosion amount obtained in the second corrosion amount calculating step;
Based on the amount of residual reinforcement of the shear reinforcement and the main reinforcement, a shear strength calculation step of calculating the shear strength of reinforced concrete,
A bending strength calculation step of calculating the bending strength of the reinforced concrete, based on the remaining reinforcing bar amount of the main reinforcing bar,
The shear strength of the reinforced concrete obtained in the shear strength calculation step, and the bending strength of the reinforced concrete obtained in the bending strength calculation step, based on the bending shear strength ratio calculation step of calculating the bending shear strength ratio of the reinforced concrete based on,
Bending shear strength ratio of the reinforced concrete obtained in the bending shear strength ratio calculation step, and a preset threshold, by comparing the proof strength of the reinforced concrete structure by comparing the strength,
A method for evaluating the strength of a reinforced concrete structure, comprising:
時間の経過と前記主筋の腐食量との関係を、第２腐食進行推移として推定する、第２腐食進行推移推定工程と、
をさらに備えた、ことを特徴とする請求項１記載の鉄筋コンクリート構造物の耐力評価方法。 Estimating the relationship between the passage of time and the amount of corrosion of the shear reinforcement as a first corrosion progress transition, a first corrosion progress transition estimation step,
Estimating the relationship between the passage of time and the amount of corrosion of the main bar as a second corrosion progress transition, a second corrosion progress transition estimation step,
The method for evaluating the strength of a reinforced concrete structure according to claim 1, further comprising:
前記主筋のかぶり深さ及び鉄筋径と、コンクリート強度と、を含む条件に基づいて計算を行うことで、該主筋の腐食によってコンクリートのひび割れが発生する第２ひび割れ発生時期における該主筋の腐食量を、第２ひび割れ腐食量として求める第２ひび割れ腐食量算出工程と、をさらに備え、
前記第１腐食進行推移推定工程では、前記せん断補強筋の腐食が始まる第１腐食開始時期と、前記第１ひび割れ発生時期と、該第１腐食開始時期から該第１ひび割れ発生時期までの第１ひび割れ前腐食速度と、該第１ひび割れ発生時期以降の第１ひび割れ後腐食速度と、に基づいて前記第１腐食進行推移を推定し、
前記第２腐食進行推移推定工程では、前記主筋の腐食が始まる第２腐食開始時期と、前記第２ひび割れ発生時期と、該第２腐食開始時期から該第２ひび割れ発生時期までの第２ひび割れ前腐食速度と、該第２ひび割れ発生時期以降の第２ひび割れ後腐食速度と、に基づいて前記第２腐食進行推移を推定し、
前記第１ひび割れ発生時期は、前記第１ひび割れ前腐食速度と前記第１ひび割れ腐食量に基づいて求められ、
前記第２ひび割れ発生時期は、前記第２ひび割れ前腐食速度と前記第２ひび割れ腐食量に基づいて求められる、
ことを特徴とする請求項２記載の鉄筋コンクリート構造物の耐力評価方法。 By calculating based on the conditions including the cover depth and the reinforcing bar diameter of the shear reinforcement and the concrete strength, the shear strength at the first crack generation time at which the concrete cracks due to corrosion of the shear reinforcement is generated. A first crack corrosion amount calculating step of determining a corrosion amount of the reinforcing bar as a first crack corrosion amount;
By performing the calculation based on the conditions including the cover depth and the reinforcing bar diameter of the main reinforcing bar, and the concrete strength, the amount of corrosion of the main reinforcing bar at the second crack generation time at which the concrete cracks due to the corrosion of the main reinforcing bar is calculated. A second crack corrosion amount calculation step of obtaining the second crack corrosion amount,
In the first corrosion progress transition estimating step, a first corrosion start time at which corrosion of the shear reinforcement starts, a first crack occurrence time, and a first corrosion start time from the first corrosion start time to the first crack occurrence time. Estimating the first corrosion progression based on the pre-crack corrosion rate and the first post-crack corrosion rate after the first crack occurrence time,
In the second corrosion progress transition estimating step, a second corrosion start time at which corrosion of the main rebar starts, a second crack occurrence time, and a second crack start time from the second corrosion start time to the second crack occurrence time. Estimating the second corrosion progression based on the corrosion rate and the second post-crack corrosion rate after the second crack occurrence time,
The first crack occurrence time is determined based on the first pre-crack corrosion rate and the first crack corrosion amount,
The second crack occurrence time is determined based on the second pre-crack corrosion rate and the second crack corrosion amount,
3. The method for evaluating the proof strength of a reinforced concrete structure according to claim 2, wherein:
前記第２ひび割れ腐食量算出工程では、前記主筋のうちコンクリート表面側の略半周面が腐食する条件で計算を行う、ことを特徴とする請求項３記載の鉄筋コンクリート構造物の耐力評価方法。 In the first crack corrosion amount calculation step, a calculation is performed under the condition that approximately half the circumferential surface on the concrete surface side of the shear reinforcement corrodes,
4. The method for evaluating the strength of a reinforced concrete structure according to claim 3, wherein in the second crack corrosion amount calculating step, the calculation is performed under a condition that a substantially half circumferential surface of the main reinforcement on the concrete surface side is corroded.
さらに備えた、ことを特徴とする請求項２乃至請求項４のいずれかに記載の鉄筋コンクリート構造物の耐力評価方法。 Using the amount of corrosion of the shear reinforcing bars determined based on the first progression of corrosion and the amount of corrosion of the main reinforcement determined based on the second progression of corrosion, the flexural shear strength ratio of reinforced concrete is defined as By estimating the time below the threshold, a life prediction step of predicting the life of the reinforced concrete structure,
The method for evaluating the strength of a reinforced concrete structure according to claim 2, further comprising:
前記第２腐食量算出工程では、前記第２腐食進行推移に基づいて、前記主筋の腐食量を求める、
ことを特徴とする請求項２乃至請求項５のいずれかに記載の鉄筋コンクリート構造物の耐力評価方法。 In the first corrosion amount calculation step, the amount of corrosion of the shear reinforcement is determined based on the first corrosion progress transition,
In the second corrosion amount calculation step, a corrosion amount of the main bar is obtained based on the second corrosion progress transition.
The method for evaluating the proof strength of a reinforced concrete structure according to any one of claims 2 to 5, wherein:
前記主筋の腐食によって生じたコンクリートのひび割れ幅を測定する第２ひび割れ幅計測工程と、をさらに備え、
前記第１腐食量算出工程では、前記第１ひび割れ幅計測工程で得られたひび割れ幅と、前記せん断補強筋のかぶり深さ及び鉄筋径と、を含む推定式によって該せん断補強筋の腐食量を求め、
前記第２腐食量算出工程では、前記第２ひび割れ幅計測工程で得られたひび割れ幅と、前記主筋のかぶり深さ及び鉄筋径と、を含む推定式によって該主筋の腐食量を求める、
ことを特徴とする請求項１乃至請求項５のいずれかに記載の鉄筋コンクリート構造物の耐力評価方法。 A first crack width measuring step of measuring a crack width of concrete caused by corrosion of the shear reinforcement,
A second crack width measuring step of measuring a crack width of the concrete caused by the corrosion of the main rebar,
In the first corrosion amount calculation step, the corrosion amount of the shear reinforcement is calculated by an estimation formula including the crack width obtained in the first crack width measurement step, the covering depth of the shear reinforcement, and the reinforcing bar diameter. Asked,
In the second corrosion amount calculation step, the crack width obtained in the second crack width measurement step, the cover depth of the main bar and the reinforcing bar diameter, the corrosion amount of the main bar is determined by an estimation formula including:
The method for evaluating the proof strength of a reinforced concrete structure according to any one of claims 1 to 5, characterized in that:
鉄筋径とかぶり深さの情報を読み出すとともに、該情報に基づいてせん断補強筋の腐食量を求める第１腐食量算出処理と、
鉄筋径とかぶり深さの情報を読み出すとともに、該情報に基づいて主筋の腐食量を求める第２腐食量算出処理と、
前記第１腐食量算出処理で得られた腐食量に基づいて、前記せん断補強筋の残存鉄筋量を求める第１残存鉄筋量算出処理と、
前記第２腐食量算出処理で得られた腐食量に基づいて、前記主筋の残存鉄筋量を求める第２残存鉄筋量算出処理と、
前記せん断補強筋及び前記主筋の残存鉄筋量に基づいて、鉄筋コンクリートのせん断耐力を算出するせん断耐力算出処理と、
前記主筋の残存鉄筋量に基づいて、鉄筋コンクリートの曲げ耐力を算出する曲げ耐力算出処理と、
前記せん断耐力算出処理で得られた鉄筋コンクリートのせん断耐力と、前記曲げ耐力算出処理で得られた鉄筋コンクリートの曲げ耐力と、に基づいて鉄筋コンクリートの曲げせん断耐力比を求める曲げせん断耐力比算出処理と、
前記曲げせん断耐力比算出処理で得られた鉄筋コンクリートの曲げせん断耐力比と、あらかじめ設定された閾値と、を比較することで前記鉄筋コンクリート構造物の耐力を判定する耐力評価処理と、
を前記コンピュータに実行させる機能を備えた、ことを特徴とする鉄筋コンクリート構造物の耐力評価プログラム。 In a program that causes a computer to execute a function of evaluating the strength of a reinforced concrete structure,
A first corrosion amount calculating process for reading out information on the rebar diameter and the covering depth and obtaining an amount of corrosion of the shear reinforcement based on the information;
A second corrosion amount calculation process for reading out the information on the reinforcing bar diameter and the fogging depth and obtaining the amount of corrosion of the main bar based on the information;
A first remaining reinforcing bar amount calculating process for obtaining a remaining reinforcing bar amount of the shear reinforcing bar based on the corrosion amount obtained in the first corrosion amount calculating process;
A second remaining reinforcing bar amount calculating process for obtaining a remaining reinforcing bar amount of the main bar based on the corrosion amount obtained in the second corrosion amount calculating process;
Based on the amount of residual reinforcement of the shear reinforcement and the main reinforcement, a shear strength calculation process for calculating the shear strength of reinforced concrete,
A bending strength calculation process for calculating the bending strength of the reinforced concrete,
The shear strength of the reinforced concrete obtained in the shear strength calculation processing, and the bending strength of the reinforced concrete obtained in the bending strength calculation processing, based on the bending shear strength ratio calculation processing to determine the bending shear strength ratio of the reinforced concrete based on,
Bending shear strength ratio of the reinforced concrete obtained in the bending shear strength ratio calculation process, and a preset threshold value, by comparing the strength of the reinforced concrete structure by proof stress evaluation processing,
Characterized by having a function of causing the computer to execute the above.
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