【正文】 spray exposures of 40 days or longer are realistic for simulating natural corrosion damage obtained at members of old buildings at coastal sites. ? The effect of salt spray exposure on the strength properties of the steel S500s is moderate. Yet, with regard to the observed appreciable mass loss, the increase on the effective engineering stress is essential such as to spend the reserves on strength which are required in the standards trough safety factors. ? The effect of salt spray exposure on the tensile ductility of the material is appreciable. For salt spray exposures longer than 35 days, elongation to fracture drops to values lying below the fu = 12% limit which is required in the standards. ? Present day standards for calculating strength of reinforced concrete members do not account for the appreciable property degradation of the reinforcing steel bars due to the gradually accumulating corrosion damage. Although, a revision of the standards such as to account for the above corrosion effects on the material properties seems to be required, further extensive investigation is needed to conclude on proper remendations for such a revision. References [1] Hellenic Regulation for the Technology of Steel in Reinforced Concrete。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。C. The temperature in the zone of the reinforcement material exposed inside the salt spray chamber was maintained at 35 176。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。 S, %。 本科畢業(yè)設(shè)計(jì) （ 論文 ） 翻譯 英文原文名 Tensile behavior of corroded reinforcing steel bars BSt 500s 中文譯名 BSt 500s 鋼筋抗腐蝕性能研究 班 級(jí) 姓 名 學(xué) 號(hào) 指導(dǎo)教師 填表日期 英文原文版出處 ： EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS 譯文成績(jī) ： 指導(dǎo)教師簽名： 原 文 ： 1. Introduction Steel bars in reinforced concrete carry mainly tension loads. According to the present day standards, . [1], for involving reinforcing steel in concrete structures, certain minimum values for the mechanical properties modulus of elasticity (E), yield stress (Rp), ultimate stress (Rm) and elongation to failure (fu) of the steel are required. Furthermore, the standard sets Rm/Rp [1]. With increasing service life of a reinforced concrete structure damage accumulates gradually. Nowadays, significant resources are allocated worldwide for the repair and rehabilitation of deteriorating concrete structures. Recent reports indicate that the annual repair costs for the reinforced concrete structures of the work of highways in the USA alone amounts to 20 billion USD [2]. The respective repair costs for reinforced concrete bridges in England and Wales amount to 615 million GBP [3]. Yet, although in recent years the problem of the actual residual strength degradation of ageing reinforced concrete structures has attracted considerable attention, it is far from being fully understood and, even less, resolved. It is worth noting that up to now, little work has been done to account for the effects of corrosion on the mechanical properties of the reinforcing steel bars and hence on the degradation of the load bearing ability of a reinforced concrete element [4]. Such effects are the reduction of the effective crosssection of the reinforcing steel, micro and macro cracking of concrete and finally the spalling of the concrete. The underestimation of the corrosion problem arises from the fact that under normal circumstances, concrete provides protection to the reinforcing steel. Physical protection of the reinforcing steel against corrosion is provided by the dense and relatively impermeable structure of concrete. The thin oxide layer covering the reinforcement, during concrete hydration, ensures chemical protection. The oxide layer remains stable in the alkaline concrete environment (pH 13), but begins to deteriorate when the pH of the pore solution drops below 11 [5] and [6]. The rate of deterioration due to corrosion rises when the pH drops below 9. For corrosion to mence, the oxide film must be broken or depassivated. Depassivation may occur if the alkalinity of the pore solution in the concrete pores decreases and/or peration of the chloride ions takes place. This may be caused by carbonation, especially in the proximity of cracks, or by water dilution which acpanies cracking [7], [8] and [9]. The advancing corrosion results in a reduction of the load carrying crosssection of the bars and an increase in their volume, which may cause cracking of concrete as well as an appreciable decrease on the bond strength between the reinforcing bars and concrete [10] and [11]. The above considerations do not account for the effect of corrosion on the mechanical behavior of the reinforcing steels. Most of the available studies on