Flexure was applied to a reinforced beam causing tension in rebars of a particular development or lapped splice length until failure. The RDLP we see today in ACI 318-14 was based mostly on beam tests. In contrast, the reinforcing bars in a seismic connection must withstand load reversals and intensive yielding during a major seismic event. A gravity-loaded concrete element is subject to gradual unidirectional loading. Furthermore, and most importantly, the reinforcing bars must be confined well enough to protect against the brittle-behaving concrete splitting failure mode. To increase ductility for seismic use, the reinforcing bar requires a deeper embedment depth. However, seismic connections may require a greater level of ductile response. Some ductility, or bar yielding, can be expected, and this would be reasonable for a gravity-loaded concrete element. In general, a developed bar that is cast-in-place or post-installed has been embedded deep enough into the concrete to allow the bar to at least reach its yield strength before the concrete splits apart or the bar pulls out of the concrete (Figure 1). The requirements for each loading condition, static versus seismic, are different. Ductility is a measure of how well a material deforms before it ruptures, and the gist of it is covered in a previous blog post. Considerable ductility would be expected for the latter. We also need to differentiate between developing a reinforcing bar for (1) a static (gravity) loading condition and for (2) a seismic loading condition. ACI 318-14, Section 22.9 (shear friction)īefore we get started, we need to define what it means to develop a reinforcing bar.ACI 318-14, Section 18.10 (special structural walls).
ACI 318-14, Section 18.8 (joints of special moment frames).ACI 318-14, Section 25.4 (development of reinforcement) and Section 25.5 (splices).Qualification of Post-Installed Reinforcing Bars (PIRBs).The last part of the blog covers some important considerations for using the RDLP. We will look at four design examples using Simpson Strong-Tie® SET-3G® adhesive evaluated in accordance with the RDLP of ACI 318-14, Chapters 25 and 18. Today, the RDLP can be applied to qualified adhesives as an alternative solution to the anchoring provision of ACI 318. Their contribution, and others, supported the idea that post-installed reinforcing bars could be evaluated using the rebar development length provision (RDLP) of ACI 318 that has been widely used in its current form for many decades. Their research showed that post-installed reinforcing bars (PIRBs) behave in structurally similar ways to cast-in-place reinforcing bars.
#Aci class b lap splice free#
This very informative report is free and available online through the Florida Department of Transportation.
#Aci class b lap splice series#
In their series of experiments, holes were drilled adjacent to cast-in-place bars using a carbide-tipped drill bit, and new bars were secured in these holes using an anchoring adhesive presumed to be of a type commonly used in concrete construction. I first learned about the application of the ACI 318 development length provision to post-installed reinforcing bars back in 2003 when I read Post-Installed Adhesive-Bonded Splices in Bridge Decks, authored by Ronald A. Engineers can access a free online calculation tool to easily determine the rebar development or lap splice length for either adhesive product. Additionally, SET-3G has slightly reduced edge and spacing requirements.
In general, a substantially lower installation cost can be expected using SET-3G for seismic applications. SET-3G does not carry the same limitation allowing for a considerable reduction in development length at higher values of f’c. The SET-XP evaluation report, ESR-2508, currently limits f’c to 2,500 psi for seismic applications located in seismic design category C–F. This blog has been reposted replacing SET-XP with SET-3G using the original design examples. The evaluation report, ESR-4057, was recently updated to allow the design of SET-3G adhesive for post-installed reinforcing bars using the ACI 318 development length provision.
0 kommentar(er)
