![]() If a smaller percentage of bars is lapped in one section then required lap length may be multiplied by the factor α 6 / 1.5, where α 6 = ( ρ l / 25) 0.5 and ρ l is the percentage of the bars lapped in one section. The lap lengths presented in the tables assume that >50% of the bars are lapped in one section (i.e.For ULS verifications when the provided tensile reinforcement A s,prov is more than than the required reinforcement A s,req then the required anchorage and lap lengths may be reduced by the ratio A s,req / A s,prov, however the minimum required anchorage length l b,min the minimum required lap length l 0,min should be provided in accordance with EN §8.4.4(1) and §8.7.3(1). the stress of the bar is assumed equal to the design yield stress f yd = f yk / γ s. The anchorage and lap lengths presented in the tables assume full utilization of the reinforcement bar yield stress, i.e.The favorable effect of these factors is described in EN §8.4.4. The required anchorage and lap length may be further reduced when one or more of the following conditions are present: a) adequate concrete cover, b) adequate confinement by transverse reinforcement, c) welded transverse bars along the anchorage length, and d) compressive pressure transverse to the plane of splitting. The anchorage and lap lengths presented in the tables are conservative values for ribbed bars with diameter Φ ≤ 32 mm.The different bond regions are shown in the figure above that is reproduced from EN Figure 8.2. 'Poor' bond conditions are applicable for all other cases and also for bars in structural elements built with slip-forms, unless it can be shown that 'good' bond conditions exist. 'Good' bond conditions are applicable when any of the following conditions is fulfilled: a) Vertical bars or almost vertical bars inclined at an angle 45° ≤ α ≤ 90° from the horizontal, b) bars that are located up to 250 mm from the bottom of the formwork for elements with height h ≤ 600 mm, or c) bars that are located at least 300 mm from the free surface during concreting for elements with height h > 600 mm.When adequate cover is not present the anchorage and lap lengths for other-than-straight bars in compression should be used instead. The condition of adequate cover c d > 3 Φ for other-than-straight bars in tension is defined in EN Figure 8.3.The detailing rules and the equivalent anchorage length for each of these standard shapes are defined in EN Figure 8.1. Other-than-straight bar shapes include a) standard bend, b) standard hook, and c) standard loop.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |