Browsing by Subject "Lap splice"

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Bar development and tension lap splice of high-strength reinforcing steel
(2022-08-15) Espanol, Cheska; Bayrak, Oguzhan, 1969-
High-strength reinforcing steel with yield strengths up to 100 ksi have been implemented in design code, but it is not common in practical bridge design. High-strength reinforcement bears opportunities for higher load-carrying capacity, reduced congestion, cost savings, and corrosion-resistance in bridge components. However, the serviceability and the validity of current code provisions shall be further investigated for state departments of transportation to apply this material in practice. In particular, bar development and tension lap splice provisions of high-strength reinforcement should be studied, and the serviceability performance in terms of crack control must be evaluated. There is limited data on the serviceability performance of beams with high-strength rebar using larger bar sizes. Therefore, the research team at the University of Texas aims to expand the database of beam-splice tests by conducting four-point bending tests on four specimens containing No. 11 bars for longitudinal reinforcement either in ASTM A615 Grade 60 or Grade 100 steel. Through the results, the effects of steel grade and the presence of a lap splice on strength and serviceability performance can be evaluated. Furthermore, design recommendations and conclusions on the applicability of current design code development length and lap splice provisions using high-strength reinforcing steel are drawn.
Retrofit of deficient lap splice with post-installed anchors
(2015-12) Beiter, Katelyn Sean; Bayrak, Oguzhan, 1969-; Hrynyk, Trevor D
As concrete infrastructure ages or is re-purposed, there is an increasing need for efficient retrofit solutions, with deficient lap splices being one of many research areas. A possible method to increase the capacity of deficient lap splices is to use post-installed undercut anchors. These anchors function as active confinement in the splice region, potentially allowing members with inadequate lap splice lengths to reach the required design capacity. The solution presented in this thesis requires access to only one face of the reinforced concrete specimen, which could facilitate implementation on existing structures. However, limited research has been done on the use of post-installed anchors as a retrofit strategy for lap splices, and previous research on the retrofit of deficient lap splices has focused primarily on the use of either carbon fiber or metal jackets. To evaluate the capabilities of this retrofit solution, four large-scale tests on beam specimens have been completed at The University of Texas at Austin. The first specimen tested contained the full lap splice length as required by ACI 318-71 provisions, while in the other three, only half of that lap splice length was provided. The specimen with the full lap splice length was tested as a control specimen and one of the specimens with half the lap splice length was tested without a retrofit to determine baseline behavior. These tests formed the basis to evaluate the effectiveness of the retrofit techniques implemented on the other two specimens. Results from these tests indicated that post-installed anchors could enhance both the strength and ductility of members with deficient lap splices, but the enhanced members demonstrated limited ductility.