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There are only a few studies related to the effect of the hybrid fiber reinforcement on the flexural behavior of full‐scale beam specimens having lap‐spliced length. Thus, this study will ensure important experimental data about the effect of macro steel fibers blended with micro steel fibers on lap‐spliced length. The aim of this study was to investigate the influence of hybrid steel fiber reinforcement on the flexural behavior of full‐scale reinforced concrete beams having different lap‐spliced bars. A sum of three traditional concrete mixtures including a total of 1% fiber by volume fraction was adopted: control mixture without steel fiber, only macro steel fiber and hybrid steel fiber reinforced mixtures. For this purpose, 18 full‐scale beams (200 × 300 × 2000 mm) having three different lap‐spliced length (15, 25, and 35Ø) as tension steel bars were produced and tested under four‐point bending to examine flexural behavior, mode of failure, ductility, and energy absorption capacity properties. In conclusion, the hybrid fiber reinforcement caused the highest increase in the load carrying capacity of the beam specimens. Besides, the hybrid fiber reinforced beam specimens exhibited excellent ductility and energy absorption capacity compared to single fiber reinforced beam specimens. On the other hand, it can be addressed that the hybrid fiber reinforced structural elements had a vital important to compensate the application errors and carelessness in steel bar workmanship, inadequate the lap‐spliced length as per the codes. It can be emphasized that the lap‐spliced length as per the building codes can be reduced in 40% by containing hybrid steel fiber (0.8% macro‐0.2% micro) reinforced concrete without a reduction in load carrying capacity, ductility, and energy absorption capacity compared to control beam specimens without fiber.

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Bu çalışmada, tek ve karma lif takviyesinin aderans dayanımına etkisini incelemek için altı adet tam ölçekli 200x300x2000 mm boyutlarında betonarme kiriş numunesi dört noktalı eğilme altında test edilmiştir. Bu amaçla, betonarme kiriş numuneleri lif takviyesiz, tek lif (%1 makro çelik lif) ve karma lif (%0.8 makro ve %0.2 mikro çelik lif) takviyeli olarak döküldü. Her bir kiriş numunesi, çekme bölgesinde iki adet donatı çeliğinin açıklık ortasında bindirmeli ekli olarak tasarlanmıştır. Bindirme boyu donatının akma dayanımına ulaşmadan önce bindirme bölgesinde beton örtüsünün yarılmasıyla aderans göçmesi gösterecek şekilde seçilmiştir. Deneysel çalışmada, donatı çapı, bindirme boyu ve donatı detayları sabit tutulurken, lif tip ve kombinasyonları değişken olarak belirlenmiştir. Sonuç olarak, lif takviyeli tüm betonarme kiriş numunelerinin beton ve çelik donatı arasındaki aderans dayanımı, lif takviyesiz kiriş numunelerine göre artış gösterirken, karma lif takviyeli kiriş numunelerinin aderans dayanımı ise en yüksek bulunmuştur. Karma lif takviyeli kiriş numunelerinde sünek göçme gözlemlenmiş ve çoklu çatlak davranışı sonucu genişliği daha az fakat daha fazla sayıda çatlak oluştuğu belirlenmiştir. Ayrıca, lif takviyeli kiriş numunelerinden elde edilen aderans dayanımına ait deneysel verilerin, analitik bulgularla çok iyi bir uyum içinde olduğu bulunmuştur.In this study, six reinforced concrete (RC) beams with the sizes of 200x300x2000 mm were tested under four-point bending to investigate the effect of single and hybrid fiber reinforced on the bond strength of reinforcing bar. For this purpose, the reinforced beams were cast as no fiber, single fiber (1% macro steel fiber) and hybrid fiber (0.8% macro and 0.2% micro steel fiber) reinforced. Each beam was designed to include two bars in tension, spliced at the center of the span. The splice length was selected so that bars would fail in bond, splitting the concrete cover in the splice region, before reaching the yield point. In experimental work, the diameter of bars, splice length and bar details was selected as constant while the fiber type and combination was variable. Finally, it was found that all beams with steel fiber reinforced had higher bond strength between concrete and steel bar than the beams without steel fiber while the beams with hybrid steel fiber reinforced had highest bond strength. A ductile failure was observed in the hybrid fiber reinforced beam specimens and it was determined that the result of multiple-crack behavior less crack width but more numbers cracked. Moreover, experimental data related to the bond strength obtained from RC beams with steel fiber were in very good agreement with analytical results.

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