【正文】 teel bars and slabs with corroded reinforcement. A sudden failure of slabs in flexure was observed when the degree of reinforcement corrosion expressed as percent mass loss exceeded 13%. The above results on the mechanical behavior of corroded reinforcing steels refer to BSt 420s of DIN 488, (S420s according to the Hellenic standards). The above results clearly indicate the need to account for the effects of corrosion on the mechanical properties of the reinforcing steel BSt 500s (S500s according to the Hellenic standards) which at present is almost exclusively used in reinforced concrete structures. It is worth noting that corrosion damage of the reinforcement, is expected to bee more noticeable in new constructions using reinforcing steel S500s, given the fact that this type of steel exhibits greater mass loss due to corrosion pared to steel classes S400 and S220 [19]. Recall that many reinforced concrete structures are located in coastal areas with an intense corrosive environment. On the other hand, a wide spread use of corrosionresistant steel reinforcing bars should not be expected as these bars cost about six to nine times more than plain carbon steel reinforcing bars. In the present study, the effects of corrosion on the tensile behavior of reinforcing steel bars Class S500s tempcore are investigated. The specimens were precorroded using laboratory salt spray tests for different exposure times. The dependencies of the degradation of the tensile properties on the corrosion exposure time have been derived. The tensile properties of the corroded material were pared against the requirements set in the standard for involving steels in reinforced concrete structures. 2. Experimental research The experiments were conducted for the steel S500s tempcore, which is similar to the BSt500S steel of DIN 488 part 1 [20]. A stress–strain graph of the uncorroded material is shown in Fig. 1. The chemical position (maximum allowable % in final product) of the alloy S500s is: C, %。8). From the bars, tensile specimens of 230 mm length were cut. The gauge length was 120 mm according to the specification DIN 488 Part 3 [22]. Prior to the tensile tests, the specimens were precorroded using accelerated laboratory corrosion tests in salt spray environment. . Salt spray testing Salt spray (fog) tests were conducted according to the ASTM B11794 specification [23]. For the tests, a special apparatus, model SF 450 made by Cand W. Specialist Equipment Ltd. was used. The salt solution was prepared by dissolving 5 parts by mass of Sodium Chloride (NaCl) into 95 parts of distilled water. The pH of the salt spray solution was such that when dissolved at 35 176。C. When exposure was pleted, the specimens were washed with clean running water to remove any salt deposits from their surfaces, and then were dried. In addition, a number of steel bars of the same length were exposed to the salt spray for 1, 2 and 4 days to monitor the corrosion damage evolution. . Mechanical testing procedure The precorroded specimens were subjected to tensile tests. All mechanical tests are summarized in Table 1. Table 1. Tensile tests for S500s 216。 Progress and Product Update. Washington, DC: National Research Council。 1990. p. 174. [13] . Thomas and . Mathews, Performance of pfa concrete in a marine environment – 10year results, Cement Concrete Compos 26 (2020), pp. 5–20. [14] T. Yonezawa, V. Ashworth and . Procter, Pore solution position and chloride effects on the corrosion of steel in concrete, Corrosion 44 (1988), pp. 489–499. [15] . Montemor, . Simoes and . Salta, Effect of fly ash on concrete reinforcement corrosion studied by EIS, Cement Concrete Compos 22 (2020), pp. 175–185. [16] B. Elsener, Macrocell corrosion of steel in concrete – implications for corrosion monitoring, Cement Concrete Compos 24 (2020), pp. 65–72. [17] C. Arya and . Vassie, Influence of cathodetoanode area ratio separation distance on galvanic corrosion currents of steel in concrete containing chlorides, Cement Concrete Res 25 (1995), pp. 989–998. [18] . Almusallam, Effect of degree of corrosion on the properties of reinforcing steel bars, Construct Build Mater 15 (2020) (8), pp. 361–368. [19] Mpatis G, Rakanta E, Tsampras L, Mouyiakos S, Agnantiari G. Corrosion of steel used in concrete reinforcement, in various corrosive environments, Technical Chamber of Greece, 13th Hellenic Convention for Concrete. vol. II, Rethymnon, Crete。 1995. p. 1–8. [24] Hellenic AntiSeismic Code 2020 (EAK 2020). [25] ASTM G1 – 90, Standard practice for preparing, cleaning, and evaluating corrosion test specimens. [26] . Sih and . Chao, Failure initiation in unnotched specimens subjected to monotonic and loading, Theor Appl Fract Mech 2 (1984), pp. 67–73. [27] . Jeong, O. Orringen and . Sih, Strain energy density approach to stable crack extension under section yielding of aircraft fuselage, Theor Appl Fract Mech 22 (1995), pp. 127–137. 譯 文 ： BSt 500s 鋼筋抗腐蝕性能研究 1. 前言 在鋼筋混凝土中鋼筋主要承受拉力 . 根據(jù)今天的標準 ,例如 [1]、對涉及鋼筋混凝土結(jié)構(gòu)、最小彈性模量 (E)、屈服強度 (Rp),極限壓力 (Rm)和鋼筋的塑性 (fu)等是必要的 . 此外 ,這個標準規(guī)定 Rm/Rp [1]. 在日益鋼筋水泥結(jié)構(gòu)的壽命逐漸累積損失 . 目前 ,全世界的重要資源分配修復(fù)混凝土結(jié)構(gòu)惡化 . 最近的報告顯示 ,每年的維修費鋼筋混凝土結(jié)構(gòu)的公路網(wǎng) ,僅相當于美國的 20 億美元 [2]. 有關(guān)鋼筋混凝土橋梁維修費英格蘭和威爾士 億英鎊 等于 [3]. 然而 ,盡管近年來實際問題殘余力量鋼筋混凝土結(jié)構(gòu)老化退化 ,引起相當大的注意 ,但還遠沒有充分了解 ,更不用說解決 . 值得注意的是 ,到現(xiàn)在為止 ,沒有進行過工作 ,占侵蝕影響的機械性能加固鋼筋 ,所以就退化的承載能力的鋼筋混凝土部分 [4]. 這些都影響了有效降低截面的鋼筋、混凝土的微觀和宏觀裂縫 和 最后的水泥剝落 . 被低估的腐蝕問題的出現(xiàn) ,是因為在正常情況下 ,具體規(guī)定了保護鋼筋 . 對人身保護的鋼筋腐蝕提供了較為稠密 ,不透水的混凝土結(jié)構(gòu) . 薄的氧化層復(fù)蓋加固 ,在具體水化、化學(xué)防護保障 . 在保持穩(wěn)定的堿性氧化物層 的具體環(huán)境 (酸堿度 13),而開始惡化時的孔隙榮獲解決少于 11 [5] 和 [6]. 由于故 障率低于酸堿腐蝕時上漲 9. 開始的腐蝕 ,氧化或 depassivated電影必須打破 . 如果堿度 depassivation可能發(fā)生的孔隙減少毛細孔的具體辦法和 /或氯離子滲透的發(fā)生 . 這可能是造成碳化 ,特別是在靠近裂縫 ,伴隨水稀釋 的作用產(chǎn)生裂縫 [7], [8]和 [9]. 進一步 腐蝕造成的削減負荷截面酒吧和增加其數(shù)量 ,這可能造成的裂痕 ,以及具體明顯下降的債券之間的實力和鋼筋混凝土 [10]和 [11]. 上述因素的影響 ,還不是在腐蝕鋼筋鋼機械行為 .