Alternative Splicing Options for Ultra-High-Performance Concrete (UHPC) H-Piles

Odelola, Michael; Khedmatgozar Dolati, Seyed Saman; Mehrabi, Armin; Garber, David

doi:10.3390/buildings15030481

Open AccessArticle

Alternative Splicing Options for Ultra-High-Performance Concrete (UHPC) H-Piles

¹

Department of Civil and Environmental Engineering, Florida International University, Maimi, FL 33174, USA

²

Structures Section, Henningson, Durham & Richardson (HDR), Inc., Doral, FL 33166, USA

³

Federal Highway Administration Resource Center, Baltimore, MD 21201, USA

^*

Authors to whom correspondence should be addressed.

Buildings 2025, 15(3), 481; https://doi.org/10.3390/buildings15030481

Submission received: 2 December 2024 / Revised: 7 January 2025 / Accepted: 11 January 2025 / Published: 4 February 2025

(This article belongs to the Section Building Structures)

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Abstract

:

Pile splicing is generally considered in construction because of transportation limits, length requirements, construction means and methods, and strength capacity. A major challenge in the use of precast prestressed UHPC piles is the lack of efficient and effective splicing solutions. To address the problem, this study evaluated different pile splicing methods for UHPC H-piles and their constructability. The analysis and design for strength capacity and detailing presented here are based on relevant established guidelines and design codes for UHPC. This study assessed two pile splicing methods: epoxy-bonded dowels and near-surface mounted bars (NSMBs). The analysis demonstrated that the epoxy-bonded dowel method provides a moment capacity that is 127% of the pile moment capacity in the strong direction and 139% of the pile moment capacity in the weak direction. In comparison, the NSMB method achieved 121% in the strong direction and 106% in the weak direction. Both methods developed the established strength capacity requirements. The constructability of both pile splicing options was evaluated to provide practical guidelines for their preparation in preplanned and unplanned situations. The results reported are for 18-inch UHPC H-piles; however, the construction and analytical approach applies to other pile sizes as well. The pile splicing options developed are recommended for further experimental investigations.

Keywords:

precast prestressed concrete piles; H-shape piles; UHPC; splicing; near-surface-mounted bars; epoxy-bonded dowels; constructability; construction

1. Introduction

Different types of piles (e.g., timber, concrete, steel, or composite) are frequently used for bridge foundations in the United States. While timber piles are sometimes used for smaller bridges, concrete and steel piles are more widely employed. Concrete piles with conventional reinforcement steel can be cast in place, but precast prestressed concrete piles and steel piles are typically driven on site. However, both pile types have some limitations, especially regarding durability, driveability, and performance.

Conventional prestressed concrete piles with carbon steel strands commonly experience corrosion, especially in marine environments. UHPC is a high-performance cementitious material with higher compression and tensile strengths when compared to normal concrete, sustained post-cracking tensile strength, low permeability, and good long-term durability [1,2,3,4,5]. One application being explored for UHPC is driven piles in foundation construction [6]. The use of UHPC H-piles has a significant impact on the long-term durability and performance of the piles, and it has been shown from previous testing to also improve the driveability of the piles [7,8]. One of the limiting factors for the use of UHPC piles is the availability of a viable option to splice them together in preplanned and unplanned situations. The preplanned situation refers to the case where the need for connection is known beforehand at the design stage. An unplanned situation refers to a case where the need for connection arises at the construction site without prior knowledge. The durability of the pile splice is crucial during the design and construction phases. Therefore, the use of corrosion-resistant materials in the pile splice system components is necessary to guarantee the substantial service life of the splicing system.

There has been little previous research on UHPC pile splices. The research work available has focused only on the welded splice option for 10-inch H-piles [9], in which the connection is too complex, lacks durability, and cannot be used for unplanned joints. The overall objective of this research is to conduct an analytical evaluation of alternative UHPC pile splice methods and develop construction details for the splice systems, which can be further investigated experimentally. The results of this study showing the applicability and constructability of the new proposed connections, as well as the methodology for analyzing and designing the UHPC pile splices, are expected to provide useful information needed for developing more effective, durable, and economical systems for establishing UHPC pile splices. This study explores two pile splicing techniques: epoxy-bonded dowels and near-surface mounted bars (NSMBs). They offer relatively simple connection designs and applications; these methods are well-suited for both preplanned construction and unplanned situations. The proposed epoxy-bonded dowel pile splicing method in this study uses conventional carbon steel for the dowel bars. However, the material properties can be modified to incorporate corrosion-resistant bars such as stainless steel and titanium bars with similar or higher strength capacity. UHPC piles are known for their excellent durability properties, and it is essential to select a splicing technique that guarantees that the joint’s durability matches or exceeds that of the original pile. This approach ensures that the splice does not compromise the pile’s performance or lifespan, maintaining its effectiveness throughout the intended service period.

2. UHPC Precast Prestressed Concrete Piles

Precast prestressed concrete piles (PPCP) are the most commonly used types of concrete piles. Depending on the conditions of the foundation and the type of concrete pile chosen, the pile’s load-bearing capacity can be developed via skin friction, point bearing, or a combination of the two [10]. PPCPs constructed with UHPC materials have the potential to overcome the constraints of other piling solutions, such as durability, weight consideration, and strength. Research studies on the durability of UHPC [2,11,12,13,14,15,16] have shown that UHPC class materials are more resilient than regular concrete and can be utilized to increase concrete structure’s service life, particularly in marine environments. UHPC piles allow the application of high prestressing ratios, reduce the spacing between the strands, and exhibit improved driveability [17,18,19]. Additionally, structural members can be made of smaller cross-sections, leading to more efficient material usage.

Numerous alternatives exist for UHPC pile shapes, including square, circular, octagonal, and H-shaped configurations. The overall objective of UHPC pile section development is to optimize the cross-section of the shape in terms of driveability, material usage, strength capacity, and weight. Some of the section types considered for UHPC piles are presented in Table 1. Out of the options considered, H-piles have numerous advantages that make them ideal for most pile foundation constructions.

A sample elevation and plan details for an 18-inch UHPC H-pile from the Florida Department of Transportation (FDOT) developmental Standard Plans for UHPC H-piles are shown in Figure 1 [20]. The pile is H-shaped at both ends (end blocks not included). U-bar stirrups were used, and the spacing of the stirrup differs according to the shear capacity requirement at the locations. The pile section shows the strand configuration: 10 No. of 0.6 in. diameter strand, grade 270 low-relaxation strands, each stressed at 42.9 kips.

3. UHPC Pile Splicing

Construction with long PPCP can lead to complications, which can include the cracking of long piles during handling, the extreme weight of the piles, and the overall cost associated with the transportation of long piles [21]. To address these problems, shorter pile lengths can be prefabricated and spliced together at the construction site [22]. Pile splicing may also be required to allow for further driving of a pile to reach its specified bearing capacity [23]. Pile splices are defined as any method of joining precast pile segments in the field during driving so that driving may continue. The splicing process starts with the positioning of the first pile (lower pile segment) after it is driven into the ground using the appropriate pile splicing method, and the lower and upper pile segments are connected to form a continuous long pile; the splicing process is illustrated in Figure 2.

Splicing PPCP has traditionally been challenging because the attachment detail requires preplanned considerations, and cast-in connection details at the precast plants or on-site coring and doweling are needed when necessary. A pile splice can fail at either the splicing component or the connections between the splicing component and the pile segments. Effective splicing of prestressed concrete piles can reduce or eliminate some problems associated with the installation of long piles. Proper splicing methods eliminate the need to predict precise pile lengths and allow extensions of piles when necessary [24].

Pile splices should also be designed to provide a service life similar to the piles. Pile splices create a discontinuity in the UHPC matrix, which allows for moisture to reach the pile splice reinforcement and the ends of the UHPC piles. Corrosion-resistant materials can be used to create compatible service lives between the pile splice and the UHPC pile.

3.1. Evaluation of UHPC Pile Splicing Options

Some splicing methods have been successfully used for conventional precast prestressed concrete piles, along with other new methods proposed for this purpose [21,24,25]. These splicing systems can also be adapted for UHPC pile sections.

Aaleti et al. [26] developed a mechanical connection design for UHPC H-piles, which consist of steel plate embedment, as illustrated in Figure 3. The welded splice type was designed to achieve at least 50% of the pile’s tension capacity and 100% of its moment and shear capacity. This type of connection requires significant preparation at the precast plant, which is not applicable to the unplanned situation and is susceptible to corrosion.

There are other connection types similar to the welded connection described above that are under consideration by the industry (unpublished) for UHPC piles, which utilize mechanical components such as locked pins, welded metal studs, and splice-tensioned rods. However, these splicing details tend to be complex, pose durability issues due to corrosion, and can be challenging to install. Zeng et al. [27,28] proposed the use of FRP bars and grouted sleeve connections for UHPC precast members, including box and cylindrical elements, as well as solid beam elements. They tested the connection and concluded that they performed well for flexure and ductility. However, this connection did not consider the case of precast prestressed members and will not be applicable to unplanned construction situations. Some investigations [6,29,30] have explored the connection of UHPC piles to other bridge components, such as pile-to-abutment connections, and have concluded that UHPC piles are a viable alternative for integral abutment bridges due to their exceptional durability, vertical and lateral load performance, and resistance during pile installation.

For a pile splice system to be considered viable, it must be evaluated using some criteria such as strength capacity, time and effort used to prepare the pile splice components, durability, and affordability [19].

According to the literature review on the available pile splice systems [31], the following two pile splicing systems are selected for further evaluation for UHPC pile splicing, and the designs for each system are presented in this study.

Epoxy-bonded dowel: Epoxy-bonded dowel pile splices are commonly used in conventional precast prestressed concrete piles, especially in the state of Florida. In the dowel-type splicing method, holes are cast or drilled into the lower pile segment to receive the dowel bars from the upper segment of the pile, as illustrated in Figure 4. Dowel rebars can be made of carbon steel, stainless steel, CFRP, or GFRP bars [32,33]. The dowels must have adequate length to bond with the other pile segments [33]. Resin and cementitious grouts, as well as UHPC, can be used as fillers and bonding agents. Corrugated ducts are utilized to create holes in preplanned situations for ease of installation. During an unforeseen situation, dowel holes can be formed in the bottom pile system through coring, which necessitates a certain level of technical expertise [32].
Near-Surface-Mounted Bar (NSMB): This pile splicing method involves applying epoxy adhesives to external grooves on the concrete piles, which are then filled with FRP (or other types of) bars to connect two pile segments, as shown in Figure 5. Titanium bars have also been used as NSM bars [34]; however, because of their relatively lower strength, they do not serve the purpose of this study. An alignment bar in the form of a spar plate can be used between two pile segments to establish the connection, and FRP strips are additionally employed to reinforce the splice connection. The system can be employed in both preplanned and unplanned pile splicing situations, as the grooves can be cut in or formed during casting. The utilization of corrosion-resistant bars, such as FRP bars, enhances durability [35,36,37].

3.2. Major Features of the Proposed New UHPC Pile Splicing Options

The connection methods introduced in this study for UHPC H-piles, epoxy-bonded dowels, and NSMBs have some features that make them advantageous over other possible connection types.

They offer relatively simple connection details that are labor-friendly and time-effective.
They apply to both preplanned and unplanned construction situations.
The use of corrosion-resistant bars as the material for NSM bars and dowel bars enhances durability and corrosion resistance, resulting in improved performance in corrosive environments such as marine areas.
If designed properly, the connection guarantees the structural performance and the efficiency of the connected precast prestressed UHPC piles.

4. Analysis of Pile Splice Options

In this section, the selected splicing options were examined, and their bending strengths were compared to available requirements. One of the requirements is the strength capacity stated in FDOT Standard Specification for Road and Bridge Construction [38] for preplanned mechanical splices. Another requirement is to develop a bending capacity equivalent to 80% of the pile bending capacity. The latter criteria were chosen on the basis that the required moment capacity for standard pile splices using normal concrete is about 80% of the moment capacity obtained by section analysis for those piles [21,38,39].

4.1. Pile Splice Requirements (FDOT)

The pile splice requirements vary across states. In this study, the design standards for splicing conventional prestressed concrete piles in the state of Florida based on FDOT Standard Specification for Road and Bridge Construction [38] were used since UHPC-specific requirements have not yet been established in the standard. Section 455-7.8 of the standard states that mechanical pile splices must be capable of developing the following capacities in the pile section:

Compressive strength = (Pile cross-sectional area) × (28-day concrete strength);
Tensile strength = (Pile cross-sectional area) × (900 psi);
Bending Strength is shown in Table 2.

It is important to note that the above requirements were established for mechanical splices in normal-weight precast prestressed concrete designed to match the bending strength of the pile itself. Since the bending strength of UHPC piles differs, the second requirement is provided in the following section, specifically for UHPC H-piles, in relation to their unique pile strength.

4.2. UHPC H-Pile Strength Capacity Requirement

The second criterion used to evaluate the capacity of the pile splicing method is achieving 80% of the strength capacity of the H-pile in both the strong and weak axes. To determine this capacity, calculations were performed using the AASHTO Guide Specifications for Structural Design with Ultra-High Performance Concrete [40], based on the UHPC pile elevation and cross-section presented in Figure 1. The basic section properties and the strand configuration and properties of the UHPC H-piles are presented in Table 3, and the UHPC class material properties are presented in Table 4.

Table 5 summarizes the factored (pure) bending strength for the pile size derived by the section analysis. These capacities were used in the evaluation of the UHPC H-pile splice methods in the following sections.

5. Design of UHPC H-Pile Splice

The section analysis is considered for two pile splicing methods: epoxy-bonded dowel and NSMB. The pile section and size considered in this process is an 18-inch UHPC H-pile section. Using the FDOT requirements, the compressive strength requirement is calculated to be 5670 kips, and the tensile strength is 291.6 kips. The following sections present the section analysis procedures for both pile splicing methods.

5.1. Analysis for Design of Epoxy-Bonded Dowel Pile Splicing Method

Figure 6 shows a cross-section of the pile at the splicing joint with the position of the dowel bars and the section’s basic properties. Section analysis was performed to estimate the strength capacity of the epoxy-bonded dowel pile splice at the connection region for the 18-inch UHPC H-pile section.

An illustration of the stress–strain relationship of the UHPC and the dowel bar with no prestressing strands at the splice region is shown in Figure 7. Since the splice section of UHPC is discontinued, the effective tension force of the UHPC was not included in the analysis. While other sizes can be used for the dowel bars, the size selected here is #10 to match that prescribed for piles using normal concrete.

In calculating the moment and forces at equilibrium, the material model considered for UHPC and the steel reinforcement bar are shown in Figure 8. The properties of the dowel bar can be modified for stainless steel with similar or better durability.

Material properties:

The basic properties of the dowel bar selected are presented in Table 6, while the properties of the UHPC class material used in the design process are presented in Table 7.

Appendix A provides detailed calculations for the design of the epoxy-bonded dowel pile splicing method. The calculation results show that the factored bending strength of the strong axis is 343 kip-ft, while for the weak axis, it is determined to be 316 kip-ft.

5.1.1. Dowel Bar Embedment Length

For precast prestressed piles using normal concrete, the embedment length of the dowel is taken to be equal to the development of prestressing strands in the concrete. This presents some challenges due to the need for a relatively long dowel projection form in the upper pile segment, as well as a long hole in the lower pile segment. For normal concrete, this issue is resolved by the use of auxiliary bars in the lower pile segments. However, the use of UHPC enables a strand development length that is similar to the bar splice length, as shown by calculations in Appendix B. Therefore, for the case of UHPC piles, the use of auxiliary bars is not necessary, and the projection length of the dowel from the upper pile segment can also be taken to be equal to the strand development length in UHPC. This will also eliminate some construction constraints related to reinforcement congestion in the lower pile segment and in the case of an unplanned situation. The various lengths shown in Figure 9 include the embedment length of the dowel bars in the upper pile segment (L′_D), the embedment length of the dowel bars to be inserted in the lower pile segment (L_D), and the length of the dowel hole at the lower pile segment, which is calculated by adding an additional 2 in to the calculated embedment length.

Detailed calculations regarding strand development length and bar embedment length are presented in Appendix B, and the results are summarized in Table 8.

5.1.2. Bonding Agent for Epoxy-Bonded Dowel Pile Splicing Method

Epoxy or UHPC grout can be used to fill the interface space between the upper and lower pile segments and the dowel holes in the lower pile segment in a precast prestressed concrete pile splice. Before the splicing process can be completed, the epoxy or UHPC must develop sufficient strength. The epoxy mixed with fine sand shall conform with Section 926 of the FDOT Standard Specifications [38]. Also, the UHPC grout material must satisfy the requirements in the AASHO LFRD Guide Specifications for structural design with UHPC.

5.2. Analysis for Design of NSMB Pile Splice

Figure 10 shows the illustration of the pile section with the NSMB pile splicing system selected to demonstrate the analysis process and some basic properties. The placement and configuration of the NSM bars are based on the recommendations of ACI 440-17R [41]. The minimum clear groove spacing and the clear edge distance are necessary to minimize the acceleration of debonding failure.

The moment capacity of the spliced section can be determined by analyzing the composite section of the near-surface-mounted (NSM) bars and UHPC without considering any prestressing across the joint and neglecting the tensile effect of UHPC class material at the splice section. FRP (carbon fiber) bars are used for NSMB to take advantage of their high strength and durability. An illustration of the strain, stress, and force diagrams across the depth of the splice region is shown in Figure 11. The details can be adjusted to obtain the level of strength required.

In calculating the moment and forces at equilibrium, the material model considered for UHPC FRP bars are shown in Figure 12.

The properties of the NSM bar material used in the analysis are presented in Table 9, and the same UHPC properties are in Table 7. The details can be adjusted to obtain the level of strength required.

The procedures and calculation for the pile splicing method, as suggested in [35], can be accessed in Appendix C; the calculation results show that the factored bending strength of the strong axis is 328 kip-ft, while for the weak axis, it is determined to be 241 kip-ft.

Bonding Agent Application for NSMB Pile Splicing Method

Epoxy grout or resin can be used to fill the groove space formed at the surface of the upper and lower UHPC pile segments. Before the application of the epoxy grout, the groove must be cleared of all debris, and a form of surface roughing can be performed using sand basting or other methods. The epoxy or resin shall be appropriate for NSMB applications.

6. Results and Discussion

6.1. Factored Strength Capacity for the UHPC Pile Splice Methods for Both Strong and Weak Axes

The factored moment capacity calculated for the UHPC H-pile splices using epoxy-bonded dowel and NSMB splicing systems are summarized in Table 10 and Table 11, respectively.

6.2. Summary of Results and Recommendations

The comparison of the bending moment capacity of the two UHPC H-pile splicing methods with established standard requirements for preplanned and unplanned situations is presented in Table 12. Based on the comparison, the following conclusions can be drawn.

Epoxy-Bonded Dowel—This pile splice method met both the requirements of FDOT and the 80% calculated pile capacity. The quality of the bonding agent used is important to the overall performance of this splice system; it must meet the required quality standards and specifications. The use of corrosion-resistant dowel bars guarantees the application of the pile splice system in marine environments.

NSM FRP bars—The pile splice method was sufficient for both strong and weak axes if compared to the 80% calculated pile capacity about the respective axis, while it met the FDOT standard requirement only for the strong axis for 18 in piles. FRP bars are important to mitigate corrosion and contribute to the durability of the UHPC pile, and the bond between the CFRP bars and the UHPC H-pile is essential for the pile splice system performance during driving and service life.

According to these results, both systems are applicable for splicing UHPC H-shape piles and are recommended for further experimental study.

7. UHPC H-Pile Splice System Constructability

Figure 13 illustrates the detailed drawings of a typical 18-inch UHPC H-pile section with an epoxy-bonded dowel pile splicing system showing the strand configuration, clear cover, and exact positioning of the bars and holes. The upper segment with the dowel bars is shown in Figure 13a, the lower pile segment with corrugated galvanized steel pipe where the dowel bars are located is shown in Figure 13b, and the various section views are shown in Figure 13c. The schematic details of the pile connection system with various elements are shown in Figure 13d. The details are for a preplanned situation, and for the unplanned situation, the holes need to be drilled with 1¾ inch diameter, which also requires a level of expertise. A constructability concern for the epoxy-bonded dowel system that remains is the concrete cover. As can be seen in Figure 14c, the concrete cover (from the center of the bar to the inside edge of the flange) for the dowels may be as little as 1⅝ in, and clear cover for the corrugated ducts can be as little as ⅝ in. This concern can be addressed through a series of small-scale tests and corrosion studies within the upcoming experimental program. Alternative solutions could include the use of smaller diameter dowel bars of higher grade (hence smaller ducts) or alternative positioning of the dowel bars in the cross-section.

Figure 14 presents detailed drawings of a typical 18-inch UHPC H-pile section with a near-surface-mounted bar (NSMB) pile splice system showing the preformed groove configuration and dimension, NSM FRP bars in the elevation, section view, and the typical groove details. The grooves need to be cut into the UHPC H-pile surface in the case of an unplanned situation. In either case, care shall be taken to create surface roughness for the grooves to enhance the bond with the bonding agent. This can be achieved using rough formwork finishes or sandblasting. The elevation view of the pile with the NSMB piles splice system is shown in Figure 14a, and the various section views and the typical groove details are shown in Figure 14b. The schematic detail of the pile connection system with various elements is shown in Figure 14c.

8. Conclusions

UHPC piles can be used to overcome the limitations of conventional concrete piles in terms of durability and performance. Pile splicing becomes necessary to join two segments of piles while driving to overcome the problems associated with limitations on transportation, driving head, weight, and handling of long piles or to provide the required capacity in unforeseen situations. Limited investigations have been performed on the proper splicing method for UHPC H-shape piles. The study reported in this research performed an analytical evaluation of pile splicing options that can be used for UHPC H-piles in both preplanned and unplanned situations with respect to their strength capacities. This investigation was carried out for an 18-inch UHPC H-pile being considered by FDOT for implementation. However, the construction and analytical approach presented in this study also applies to other pile sizes. The constructability of the selected splicing methods was also investigated. The following conclusions can be made:

This study proposes the use of two pile splicing options: epoxy-bonded dowel and near-surface-mounted (NSMB) systems.
The analysis demonstrated that the epoxy-bonded dowel method provides a moment capacity that is 127% of the pile moment capacity in the strong direction and 139% of the pile moment capacity in the weak direction. In comparison, the NSMB method achieved 121% in the strong direction and 106% in the weak direction. Both methods developed the established strength capacity requirements.
Two pile splicing options were found to have also met the capacity requirement set by the FDOT standards. The only exception is the NSMB in the weak direction. Nevertheless, even this case fulfills the requirement when compared to the 100% capacity of the pile in the weak direction.
For the case of the epoxy-bonded dowel method, the use of UHPC enables a strand development length of 30 in, which is similar to the bar splice length. Therefore, in contrast to normal concrete, the use of auxiliary bars is not necessary for UHPC piles, and both the embedment and projection length in the upper pile segment can be taken as equal to the strand development length in UHPC. This will also eliminate some construction constraints related to reinforcement congestion in the lower pile segment and in the case of an unplanned situation.
Epoxy-bonded dowels and NSMB pile splicing systems are recommended for further validation by experimental tests and field implantation for both preplanned and unplanned situations.
Concerns remain regarding the concrete cover for the epoxy-bonded dowel system and the edge distance of the holes/ducts in the flanges of the H-shaped piles. This may require the use of smaller dowel bars of higher grade and/or alternative positioning of the dowel bars in the cross-section.
Drilling into UHPC for unplanned epoxy-bonded dowel application and forming or cutting the grooves for the NSMB system may require special equipment and expertise.

9. Recommendation for Future Research

Several promising avenues can be explored to improve the understanding and application of UHPC pile splicing. Below are some key research recommendations that can contribute to the advancement of this field:

Implement comprehensive, long-term studies to evaluate the durability of various pile splice options and their components across diverse environmental conditions for a range of environmental stressors, including freeze–thaw cycles, marine exposure, and other harsh conditions. Emphasis should be placed on corrosive environments to rigorously validate the suitability and long-term viability of these splicing methods. This will provide a comprehensive understanding of their long-term durability, structural integrity, and behavior under real-world conditions.
Conduct extensive large-scale load testing to thoroughly assess the structural performance of pile splice options. This should encompass evaluations of tensile, compressive, and flexural capacities under a wide range of loading scenarios, providing a robust understanding of their structural behavior.
Investigate and develop innovative bonding methodologies to enhance the interface strength between near-surface-mounted (NSM) fiber-reinforced polymer (FRP) bars and UHPC piles. This research should focus on improving the overall structural integrity and load transfer mechanisms of the spliced connection.
Perform a thorough performance evaluation and life-cycle analysis of the UHPC pile splicing method for H-piles to assess its economic viability and long-term sustainability. When combined with the technical assessment, this analysis will offer a comprehensive understanding of the feasibility and cost-effectiveness of implementing UHPC pile splicing techniques in construction projects.
Explore the potential of integrating multiple splicing techniques within a single pile to create hybrid systems. This approach aims to leverage the strengths of different methods, potentially leading to enhanced strength, durability, overall performance, and reduced maintenance cost of the spliced pile in construction. Such cases may occur when the lower portion of the pile is in the water or soil and the upper portion is exposed, or one splicing method alone would not be able to develop the required strength.
Investigate the use of high-performance materials such as FRP and titanium for dowel and NSM bars to further enhance splicing durability.

Author Contributions

Conceptualization, M.O., S.S.K.D., A.M. and D.G.; methodology, M.O., S.S.K.D., A.M. and D.G.; software, M.O. and S.S.K.D.; formal analysis, M.O., S.S.K.D., A.M. and D.G.; investigation, M.O., S.S.K.D., A.M. and D.G.; resources, M.O., S.S.K.D., A.M. and D.G.; data curation M.O., S.S.K.D. and A.M.; writing—original draft preparation, M.O., S.S.K.D., A.M. and D.G.; writing—review and editing, M.O., S.S.K.D., A.M. and D.G.; visualization, M.O., S.S.K.D. and A.M.; supervision, A.M. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Florida Department of Transportation (FDOT), grant number BED 29 977-03.

Data Availability Statement

The data presented in this study are available on request from the corresponding authors.

Acknowledgments

The project for which this study was performed is supported by the Florida Department of Transportation (FDOT). The opinions, findings, and conclusions expressed in this publication are those of the author(s) and not necessarily those of the Florida Department of Transportation or the U.S. Department of Transportation.

Conflicts of Interest

Author Seyed Saman Khedmatgozar Dolati was employed by the company Structures Section, Henningson, Durham & Richardson (HDR) Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Appendix A. Calculation for Epoxy-Bonded Pile Splice Section Analysis (18 in UHPC Pile)

Calculate the dowel bar material properties:

Ultimate tensile strength:	$f_{s} = 60 k s i$
Modulus of Elasticity:	$E_{s} = 29,000 k s i$
Yield strain:	$ɛ_{s} = \frac{60}{29,000} = 0.00207$

Calculate the UHPC class material properties:

Modulus of elasticity of UHPC:

E_{c} = 2500 {({f'}_{c})}^{0.33}

[UHPC Guide Article 1.4.2.3]

E_{c} = 2500 \times {(17.5)}^{0.33} = 6428.987 k s i

Elastic compression strain limit:	$ε_{c p} = \frac{α {f'}_{c}}{E_{c}} = \frac{0.85 \times 17.5}{6428.987} = 0.002313$
Ultimate compression strain limit:	$ε_{c u} = 0.0035$

Calculate the area of dowel (steel) bars:

Area of dowel bars at each layer:

Layer 2:	$A_{s 2} = 4 \times 1.27 = 5.08 {i n}^{2}$
Layer 1:	$A_{s 1} = 4 \times 1.27 = 5.08 {i n}^{2}$

Calculate the strain, stress, and forces:

Calculate the strain in the dowel bars:

Layer 2:	$ε_{s 2} = ε_{c u} (\frac{d_{2} - c}{c}) = \frac{0.0035 \times (14.875 - c)}{c}$
Layer 1:	$ε_{s 1} = ε_{c u} (\frac{d_{1} - c}{c}) = \frac{0.0035 \times (3.125 - c)}{c}$

Calculate the force in the dowel bar in each layer:

Layer 2:	$T_{s 2} = A_{s 2} \times E_{s} ε_{s 2} = 5.08 \times 29,000 \times \frac{0.0035 \times (14.875 - c)}{c} = \frac{515.62 \times (14.875 - c)}{c} k i p$
Layer 1:	$T_{s 1} = A_{s 1} \times E_{s} ε_{s 1} = 5.08 \times 29,000 \times \frac{0.0035 \times (3.125 - c)}{c} = \frac{515.62 \times (3.125 - c)}{c} k i p$

Calculate the force in the UHPC:

Figure A1. Strain and neutral axis distances illustration.

From the figure:

\frac{c}{c - x} = \frac{0.0035}{0.0023}

0.0023 c = 0.0035 c - 0.0035 x

x = 0.34 c

C_{c} = 0.5 \times (ε_{c p} E_{c}) \times y \times b + (ε_{c p} E_{c}) \times x \times b

C_{c} = 0.5 \times (0.002313 \times 6428.987) \times 0.66 \times c \times 18 + (0.002313 \times 6428.987) \times 0.34 \times c \times 18

C_{c} = 179.33 c k i p s

Calculate the equilibrium (N = 0)

Equilibrium:

C_{c} = (T_{s 2} + T_{s 1})

179.33 c = (\frac{515.62 \times (14.375 - c)}{c} + \frac{515.62 \times (3.125 - c)}{c})

c = 4.87 i n .

Check for strain in the bar layer:

Layer 2:

ε_{s 2} = ε_{c u} (\frac{d_{2} - c}{c}) = \frac{0.0035 \times (14.375 - 4.87)}{4.87} = 0.006921

Since ɛ_s2 > 0.00207 (Recalculate the strain in each layer)

Equilibrium:

C_{c} = (T_{s 2} + T_{s 1})

179.33 c = (5.08 \times 60 + \frac{515.62 \times (3.125 - c)}{c})

c = 2.466 i n .

Calculating the flexural strength of the epoxy-bonded dowel splice system.

Calculate the strain in the dowel bars:

Layer 2:	$ε_{s 2} = ε_{c u} (\frac{d_{2} - c}{c}) = \frac{0.0035 \times (14.875 - 2.466)}{2.466} = 0.01761$
Layer 1:	$ε_{s 1} = ε_{c u} (\frac{d_{1} - c}{c}) = \frac{0.0035 \times (3.125 - 2.466)}{2.466} = 0.00093$

Calculate the force in the dowel bar in each layer:

Layer 2:	$T_{s 2} = A_{s 2} \times E_{s} ε_{s 2} = 5.08 \times 60 = 304.80 k i p$
Layer 1:	$T_{s 1} = A_{s 1} \times E_{s} ε_{s 1} = 5.08 \times 29,000 \times 0.00093 = 137.67 k i p$

Calculate the equilibrium (N = 0)

Equilibrium:

C_{c} = (T_{s 2} + T_{s 1})

179.33 \times 2.466 = 304.80 + 137.67

442.47 = 442.47 (o k a y)

Calculate the nominal moment capacity:

Cc, Top lever arm:

From Figure A1:

\frac{A_{1} \times d_{1} + A_{2} \times d_{1}}{A_{1} + A_{2}}

\frac{0.34 \times 0.0023 \times \frac{0.34}{2} + 0.56 \times 0.0023 \times \frac{0.66}{2}}{(0.0023 \times 0.34) + (0.5 \times 0.66 \times 0.0023)}

y_{c c} = 0.645 c = 0.645 \times 2.466 = 1.59 i n

T_s, Lower lever arm for the dowel bars:

Layer 2:	$y_{s 2} = d_{s 2} - c = 14.875 - 2.466 = 12.409 i n .$
Layer 1:	$y_{s 1} = d_{s 1} - c = 3.125 - 2.466 = 0.659 i n .$

Nominal Moment:

M_{n} = {(y}_{C c} \times C_{c}) + {(y}_{s 2} \times T_{s 2}) + {(y}_{s 1} \times T_{s 1})

M_{n} = (1.59 \times 442.47) + (12.409 \times 304.80) + (0.659 \times 137.67) = 381.39 k i p . f t

Factored Moment:

The strength reduction factor

\emptyset

used for the splice system is based on the AASHTO Guide Specifications for Structural Design with Ultra-High-Performance Concrete [40]; it was calculated to be 0.90.

{\emptyset M}_{n} = 0.90 \times 381.39 = 343 k i p . f t

A similar procedure was used in the section analysis of the epoxy-bonded pile splice for an 18-inch UHPC H-pile about the weak axis, which was calculated as 316 kip-ft.

Appendix B. Embedment and Development Length of Dowel Bar

The development length for the dowel bars embedded in UHPC is determined according to Section 10.8.2.1 of AASHTO Guide Specifications for Structural Design with UHPC [30] with reference to Section 5.10.8.2.1a (for tension development length) of AASHTO LFRD Bridge Design Specifications [31].

ȴ_{d} = ȴ_{d b} \times (\frac{λ_{r l} \times λ_{c f} \times λ_{r c} \times λ_{c r}}{λ}) (5.10.8.2.1 a - 1)

ȴ_{d b} = 2.4 d_{b} \times \frac{f_{y}}{\sqrt{{f'}_{c}}} (5.10.8.2.1 a - 2)

The basic development length will be modified when multiplied by the following factors:

K_{t r} = \frac{{40 A}_{t r}}{S \times n} (5.10.8.2.1 c - 2)

λ_{r c} = \frac{d_{b}}{c_{b} + k_{t r}} (5.10.8.2.1 c - 3)

where:

ȴ_db = basic development length (in.);
λ_rl = reinforcement location factor (use 1.0);
λ_cf = coating factor (use 1.0);
λ_rc = reinforcement confinement factor;
λ_cr = excess reinforcement factor;
λ = concrete density modification factor, should be taken as 1.0;
C_b = the smaller of the distance from the center to the bar or wire being developed to the nearest concrete surface and one-half the center-to-center spacing of the bars or wires being developed (in.);
K_tr = transverse reinforcement index;
f_y = specified minimum yield strength of reinforcement;
f’_c = compressive strength of concrete of the design (taken as 15 ksi as limited as [30]).

Calculations

ȴ_{d b} = 2.4 \times 1.27 i n . \times \frac{60 k s i}{\sqrt{15 k s i}} = 47.2 i n .

K_{t r} = \frac{{40 A}_{t r}}{S \times n}

λ_{r c} = \frac{d_{b}}{c_{b} + k_{t r}} = \frac{1.27}{2.5 + 0} = 0.508

ȴ_{d} = 47.2 \times (\frac{1 \times 1 \times 0.5 \times 1}{1}) = 23.6 i n .

ȴ_{d} = 24 i n .

Lap Splice in tension (§ 5.10.8.4.3a) AASHTO LFRD Bridge Design Specification [31]

(a): Class A Splice ${1.0 \times ȴ}_{d b} = 24 i n .$
(b): Class B Splice ${1.3 \times ȴ}_{d b} = 31 i n .$

Development Length of Prestressing Strands in UHPC

The development length of prestressing strands embedded in UHPC is determined using Sections 9.4.3.1 and 9.4.3.2 of the AASHTO Guide Specifications for Structural Design with UHPC [30].

\begin{array}{l} The transfer length, ȴ_{t} = ξ 24 d_{b} . \\ The development length ȴ_{d} \geq ȴ_{t} + 0.30 (f_{p s} - f_{p e}) d_{b} \end{array}

where:

ξ = The transfer length factor, taken as 1.0;
d_b = Strand diameter;
f_ps = Average stress in prestressing steel at the time for which the nominal resistance of the member is required (ksi);
f_pe = effective stress in prestressing steel after losses (ksi).

Development Length calculations

Strand development length is determined using Sections 1.9.4.3.1 and 1.9.4.3.2 of the AASHTO LRFD Guide Specifications for Structural Design with UHPC [30]

f_{p u} = 270 k s i

f_{p y} = 0.9 \times 270 = 243 k s i

c = 6.18 i n .

k = 2 (1.04 - \frac{243}{270}) = 0.28

f_{p s} = f_{p u} (1 - k \frac{c}{d_{p}}) = 270 \times (1 - 0.28 \frac{6.18}{16}) = 240.8 k s i

f_{p s} = 240.8 k s i

f_{p e} = 155.5 k s i

ξ = 1.0

The transfer length,

ȴ_{t} = ξ 24 d_{b} = 1.0 \times 24 \times 0.6 = 14.4 i n .

The development length,

ȴ_{d} \geq ȴ_{t} + 0.30 (f_{p s} - f_{p e}) d_{b}

ȴ_{d} \geq 14.4 + 0.30 \times (240.8 - 155.5) \times 0.6 = 29.75 i n .

ȴ_{d} = 30 i n .

Appendix C. Calculation for Near-Surface-Mounted Bar Pile Splice Section Analysis (18 in. UHPC Pile)

Step 1: Calculate the FRP bars and UHPC class material properties.

The properties of the CFRP bar properties and the UHPC class material are presented in Table 7 and Table 9.

Modulus of elasticity of UHPC:

E_{c} = 2500 {({f'}_{c})}^{0.33}

[UHPC Guide Article 4.2.3]

E_{c} = 2500 \times {(17.5)}^{0.33} = 6428.987 k s i

Elastic compression strain limit:	$ε_{c p} = \frac{α {f'}_{c}}{E_{c}} = \frac{0.85 \times 17.5}{6428.987} = 0.002313$
Ultimate compression strain limit:	$ε_{c u} = 0.0035$

Step 2: Calculate the area of CFRP bars.

Area of NSM CFRP bars at each layer:

Layer 2:	$A_{f 2} = 6 \times 0.196 = 1.176 {i n}^{2}$
Layer 1:	$A_{f 1} = 6 \times 0.196 = 1.176 {i n}^{2}$

Step 3: Determining the design strain of the NSM FRP pile splicing system.

ɛ_{f d} = k_{m} ɛ_{f u}

(A1)

ɛ_{f d} = 0.8 \times 0.015 = 0.012

Step 4: Determining the neutral axis depth, c.

Calculate the neutral axis depth:

c = 2.362 i n . (b y s o l v e r)

Calculate the strain in the CFRP bars:

Layer 2:	$ε_{f 2} = ε_{c} (\frac{d_{f 2} - c}{c}) = \frac{0.0035 \times (17 - 2.57)}{2.57} = 0.020$
Layer 1:	$ε_{f 1} = ε_{c} (\frac{d_{f 1} - c}{c}) = \frac{0.0035 \times (1 - 2.57)}{2.57} = - 0.00214$

Calculate the force in the CFRP bars at each layer:

Layer 2:	$T_{f 2} = A_{f 2} \times E_{f} ε_{f d} = 1.176 \times 22,500 \times 0.012 = 325 k i p$
Layer 1:	$T_{f 1} = A_{f 1} \times E_{f} ε_{f 1} = 1.176 \times 22,500 \times 0 = 0 k i p$

CFRP bars in the compression zone were not considered.

Calculate the strain in the UHPC (considering debonding):

Failure by concrete crushing was first considered when calculating the strain in the FRP sheet/jacket. Since the strain in layer 2 of the CFRP bar is more than the debonding strain, debonding as a failure mode was used, and the UHPC strain was recalculated as follows:

ε_{c} = ε_{f d} (\frac{c}{d_{f 2} - c}) = 0.012 (\frac{2.57}{17 - 2.57}) = 0.0022

Since

ε_{c} < ε_{c u}

, debonding will control the design.

C_{c} = 0.5 \times (ε_{c} E_{c}) \times c \times b = 0.5 \times 0.0022 \times 6429 \times 2.57 \times 18

C_{c} = 325 k i p s

It is assumed that CFRP bars do not carry compression.

Calculate the equilibrium (N = 0)

Equilibrium:

C_{c} - (T_{f 2} + T_{f 1}) = 325 - (325 - 0) = 0

Step 5: Calculating the flexural strength of the splice system.

Calculate the strain in the CFRP bars:

Layer 2:	$ε_{f 2} = ε_{c} (\frac{d_{f 2} - c}{c}) = \frac{0.0035 \times (17 - 2.57)}{2.57} = 0.020$
Layer 1:	$ε_{f 1} = ε_{c} (\frac{d_{f 1} - c}{c}) = \frac{0.0035 \times (1 - 2.57)}{2.57} = - 0.00214$

Calculate the force in the CFRP bars at each layer:

Layer 2:	$T_{f 2} = A_{f 2} \times E_{f} ε_{f d} = 1.176 \times 22,500 \times 0.012 = 325 k i p$
Layer 1:	$T_{f 1} = A_{f 1} \times E_{f} ε_{f 1} = 1.176 \times 22,500 \times 0 = 0 k i p$

It was assumed that CFRP bars do not carry compression.

Calculate the equilibrium (N = 0)

Equilibrium:

C_{c} - (T_{f 2} + T_{f 1}) = 325 - (325 - 0) = 0

Check for nominal moment capacity:

Top lever arm:

y_{C c, t o p} = \frac{2}{3} c = \frac{2 \times 2.57}{3} = 1.71 i n .

Lower lever arm for the CFRP bars:

Layer 2:	$y_{T f 2} = d_{f 2} - c = 17 - 2.57 = 14.43 i n .$
Layer 1:	$y_{T f 1} = d_{f 1} - c = 1 - 2.57 = - 1.57 i n .$

Nominal Moment:

M_{n} = {(y}_{C c} \times C_{c}) + {(y}_{T f 2} \times T_{f 2}) + {(y}_{T f 1} \times T_{f 1})

M_{n} = (1.71 \times 325) + (14.43 \times 325) + (- 1.266 \times 0) = 436 k i p . f t

Factored Moment:

The strength reduction factor

\emptyset

used for the splice system was calculated to be 0.75

{\emptyset M}_{n} = 0.75 \times 436 = 328 k i p . f t

A similar procedure was used in the section analysis of the NSMB pile splice for the 18-inch UHPC H-pile about the weak axis, which was calculated as 241 kip-ft.

Step 6: Calculate the development length of the splice system.

Development length for circular bars:

l_{d b} = f_{f d} \times \frac{d_{b}}{{4 τ}_{b}}

l_{d b} = (0.012 \times 22,500) \times \frac{0.5}{4 \times 1000} = 34.5 i n .

Step 7: Determine the groove dimensions of the splice system.

Dimension of grooves:	$1.5 \times d_{b} = 1.5 \times 0.5 = 0.75 i n .$
Clear groove spacing:	$2 \times 0.75 = 1.5 i n .$

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Figure 1. UHPC H-shaped pile details. (a) Elevation; (b) section view [20].

Figure 2. Pile splicing steps illustration.

Figure 3. UHPC pile splice details [26].

Figure 4. Epoxy dowel pile splicing method cut section: (a) positioning of the upper and lower pile segment. (b) Connecting both pile segments using epoxy bond; (c) finished epoxy-dowel-bonded pile splice system.

Figure 5. Near-surface-mounted bar (NSMB) pile splicing method cut section: (a) positioning of the upper and lower pile segments with the formed grooves; (b) connecting both pile segments using the NSM FRP bars in the preformed grooves; (c) finished NSMB pile splice system.

Figure 6. UHPC sections for 18-inch H-shaped pile.

Figure 7. Schematic representation of strain, stress, and force for the pile splice region without prestressing strands.

Figure 8. Idealized uniaxial stress–strain relationships: (a) UHPC in compression; (b) conventional steel bars in tension.

Figure 9. Embedment length illustration in epoxy-bonded dowel pile splice system.

Figure 10. NSM FRP bar configuration for UHPC H-pile section.

Figure 11. Strain, stress, and force diagram for UHPC concrete section with NSM FRP pile splicing system.

Figure 12. Idealized uniaxial stress–strain relationships: (a) UHPC in compression; (b) FRP bars in tension.

Figure 13. Illustration of epoxy-bonded dowel pile splicing system: (a) upper segment elevation; (b) lower segment elevation; (c) section views; (d) systematic illustration of the pile segment connections.

Figure 14. A typical section for NSM FRP bar splicing method: (a) elevation; (b) section views and groove details; (c) schematic illustration of the pile segment connections.

Table 1. Different shape options for UHPC piles.

Shape Type	Advantages	Disadvantages
1. Square with rectangular void	Symmetrical section Reduces cross-section while keeping the square shape.	Issues with void (unequal wall thickness if void moves).
2. Square with circular void	Potential for more splicing options (largest cross-section). Symmetrical section.	Weight is heavier than the rectangular void option. Issues with void (unequal wall thickness if void moves)
3. Octagonal with void	Optimization of the shape to strength capacity. Reduced weight.	New forms might be required. Issue with forming of the void during construction. Splicing might be difficult.
4. H-pile	Largest surface area. Surface area contributes to the side friction. Reduced weight compared to square shape. Most cast and driven pile shape in construction. Easily adopted in pile foundation.	Non-symmetrical section. Direction of pile is important during placement. New forms may be required. Inconsistent dimensions of flanges. Pile splicing could be more challenging.

Table 2. Required bending strength for pile splices from FDOT Standard Specification for Road and Bridge Construction Section 455-7.8 [38].

Pile Size	Bending Strength
18 in.	245 k-ft
24 in.	600 k-ft
30 in.	950 k-ft

Table 3. Basic properties of UHPC H-pile.

Property	Value	Strand and Prestressing	Value
Section area (in²)	324	No. of strand, s_trands	10
Section moment of inertia (in⁴)	8748	Strand stress, ksi	42.9
Section modulus (in³)	972	Total area of strand, A_ps (in²)	2.170
Weight (kip/ft)	0.349	Ultimate strength f_pu (ksi)	270

Table 4. UHPC material properties for initial analysis.

Property	Variable	Value Used
Unit weight of concrete	γ_c	155 pcf
Compression strength	f′_c	17.5 ksi
Compression reduction factor	α_u	0.85
Ultimate compressive strain	ε_cu	0.0035
Effective cracking stress	f_t,cr	0.75 ksi
Localization stress	f_t,loc	0.75 ksi
Localization strain	ε_t,loc	0.0025
Tension reduction factor	γ_u	1.0

Table 5. Estimated pure bending strength for UHPC H-pile.

Pile Orientation	Pile Capacity	80% for Pile Splices
Strong Axis	270 k-ft	216 k-ft
Weak Axis	228 k-ft	182 k-ft

Table 6. Typical properties of dowel bar.

Property		Value
Bar size		#10
Yield strength	f_y	60 ksi
Modulus of elasticity	E_s	29,000 ksi
Yield strain	$ε_{s}$	0.00207
Area of one bar	A	0.196 in²

Table 7. UHPC class material properties.

Property		Value
Compression strength	f′_c	17.5 ksi
Compression reduction factor	α_u	0.85
Ultimate compressive strain	ε_cu	0.0035
* Elastic compression strain limit	$ε_{c p}$	0.0023
* Modulus of elasticity	E_c	6429 ksi

* calculated values.

Table 8. Embedment length in UHPC pile.

Length Type	Value
Strand development length, ℓ_d	30 in.
Dowel length at upper pile segment, L′_D	30 in.
Dowel length at lower pile segment, L_D	30 in.
Dowel hole length at lower pile segment, L_H	32 in.

Table 9. Typical properties of CFRP bars.

Property		Value
Bar size		#4
Tensile strength	$f_{f u}^{*}$	406 ksi
Tensile modulus of elasticity	$E_{f u}^{*}$	22,560 ksi
Area of one bar	A	0.196 in²

Table 10. Epoxy-bonded dowel splice method (strong and weak axis) strength capacity.

Orientation	Dowel (Quantity-Bar Size)	Factored Moment Strength (kip-ft)	Embedment Length			Diagram Illustration
Orientation	Dowel (Quantity-Bar Size)	Factored Moment Strength (kip-ft)	L’_D (in.)	L_D (in.)	L_H (in.)	Diagram Illustration
Strong Axis	8-#10	343	30	30	32
Weak Axis	8-#10	316	30	30	32

Table 11. NSM FRP bar pile splice system (strong axis and weak axis) strength capacity.

Orientation	CFRP Bars (Quantity-Bar Size)	Factored Nominal Moment (kip-ft)	Groove Dimensions (in.)	Groove Spacing (in.)	Development Length (in.)
Strong Axis	12-#4	328	0.75	1.5	35
Weak Axis	12-#4	241	0.75	1.5	35

Table 12. Comparison of the calculated moment capacity with various requirements.

Pile Splice Method	Splice Moment Capacity (k-ft)		80% Calculated Pile Capacity (Pure Bending) (k-ft)		FDOT Standard Requirement (k-ft)	Meet the Minimum Requirement
Pile Splice Method	Strong Axis	Weak Axis	Strong Axis	Weak Axis	FDOT Standard Requirement (k-ft)	Strong Axis	Weak Axis
Epoxy-bonded dowel	343	316	216	182	245	Yes	Yes
NSM FRP	328	241	216	182	245	Yes	No *

* The splice can be satisfactory if compared to the 80% of the calculated pile capacity about the corresponding axis.

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Odelola, M.; Khedmatgozar Dolati, S.S.; Mehrabi, A.; Garber, D. Alternative Splicing Options for Ultra-High-Performance Concrete (UHPC) H-Piles. Buildings 2025, 15, 481. https://doi.org/10.3390/buildings15030481

AMA Style

Odelola M, Khedmatgozar Dolati SS, Mehrabi A, Garber D. Alternative Splicing Options for Ultra-High-Performance Concrete (UHPC) H-Piles. Buildings. 2025; 15(3):481. https://doi.org/10.3390/buildings15030481

Chicago/Turabian Style

Odelola, Michael, Seyed Saman Khedmatgozar Dolati, Armin Mehrabi, and David Garber. 2025. "Alternative Splicing Options for Ultra-High-Performance Concrete (UHPC) H-Piles" Buildings 15, no. 3: 481. https://doi.org/10.3390/buildings15030481

APA Style

Odelola, M., Khedmatgozar Dolati, S. S., Mehrabi, A., & Garber, D. (2025). Alternative Splicing Options for Ultra-High-Performance Concrete (UHPC) H-Piles. Buildings, 15(3), 481. https://doi.org/10.3390/buildings15030481

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Alternative Splicing Options for Ultra-High-Performance Concrete (UHPC) H-Piles

Abstract

1. Introduction

2. UHPC Precast Prestressed Concrete Piles

3. UHPC Pile Splicing

3.1. Evaluation of UHPC Pile Splicing Options

3.2. Major Features of the Proposed New UHPC Pile Splicing Options

4. Analysis of Pile Splice Options

4.1. Pile Splice Requirements (FDOT)

4.2. UHPC H-Pile Strength Capacity Requirement

5. Design of UHPC H-Pile Splice

5.1. Analysis for Design of Epoxy-Bonded Dowel Pile Splicing Method

5.1.1. Dowel Bar Embedment Length

5.1.2. Bonding Agent for Epoxy-Bonded Dowel Pile Splicing Method

5.2. Analysis for Design of NSMB Pile Splice

Bonding Agent Application for NSMB Pile Splicing Method

6. Results and Discussion

6.1. Factored Strength Capacity for the UHPC Pile Splice Methods for Both Strong and Weak Axes

6.2. Summary of Results and Recommendations

7. UHPC H-Pile Splice System Constructability

8. Conclusions

9. Recommendation for Future Research

Author Contributions

Funding

Data Availability Statement

Acknowledgments

Conflicts of Interest

Appendix A. Calculation for Epoxy-Bonded Pile Splice Section Analysis (18 in UHPC Pile)

Appendix B. Embedment and Development Length of Dowel Bar

Appendix C. Calculation for Near-Surface-Mounted Bar Pile Splice Section Analysis (18 in. UHPC Pile)

References

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