• 作者： 陳文雄
• 中文摘要： In order to develop an integrated scheme for general damage assessment and to comprehensively study the strengthening of damaged reinforced concrete members, cracking problems in reinforced concrete members were studied. Tests on 108 high strength concrete specimens and 108 normal strength concrete specimens are discussed. The main variables are the clear concrete cover thickness, Dn, bar diameter, Db, concrete strength, fc', and level of steel stress, fs. The cleavage behavior between the concrete cover and the bar surface and the length of separation, Ws, at the interface between the reinforcing bar and concrete cover under loading are studied. The crack width on the concrete surface under loading, Wc, and unloading, Wo, were measured. The typical relationship is obtained between Wo or Wc and Ws, as a function of Dn, Db, fc'and fs. This research reveals that Ws increases with increasing Dn and increasing fs ; thus, exposure of the reinforced steel to aggressive substances may increase with increasing concrete cover thickness. Comparison of the crack widths is made between the high strength concrete and normal strength concrete. It is found that Wc for the high strength concrete is somewhat smaller than the Wc for the normal concrete, but that Ws for the high strength concrete is larger than that for the normal strength concrete. The ACI equation predicts the crack width of a high strength concrete well, but with a safety margin which is smaller than that obtained for the normal strength concrete. However, high strength concrete is not so likely to resist steel corrosion from the standpoint of the internal shape of the crack.
• 英文摘要： --
• 中文關鍵字： crack, damage, concrete cover, corrosion
• 英文關鍵字： --