Factors affecting bond between precast concrete and cast in place ultra high performance concrete (UHPC)

2020 ◽  
Vol 216 ◽  
pp. 110746 ◽  
Author(s):  
Ali A. Semendary ◽  
Dagmar Svecova
Author(s):  
Mohamadreza Shafieifar ◽  
Mahsa Farzad ◽  
Atorod Azizinamini

Accelerated bridge construction (ABC) is a paradigm change in delivery of bridges. ABC minimizes the traffic interruption, enhances safety to public and workers by significantly reducing on-site construction activities, and results in longer-lasting bridges. The use of precast elements is gaining attention owing to inherent benefits of accelerated construction. Designing an economical connection is one of the main concerns for these structures. New improved materials such as ultra-high-performance concrete (UHPC) with superior characteristics can provide solutions for joining precast concrete elements. In this paper two types of column to cap beam connection using UHPC are proposed for seismic and non-seismic regions. Among the merits of the proposed details, large tolerances in construction and simplicity of the connection can be highlighted which facilitates and accelerates the on-site construction time. The experimental program was carried out to evaluate the performance and structural behavior of the proposed connections. Four specimens were subjected to constant axial compressive loads and cyclic lateral loading. Results of the experiment showed that the displacement ductility of the specimens, incorporating suggested details, demonstrated adequate levels of displacement ductility. More importantly, the proposed connections prevented the damage into capacity protected element—in this case the cap beam. Analytical and nonlinear finite element analysis on the specimens was carried out to better comprehend the behavior of the proposed connections.


Author(s):  
Charlotte Murphy

<p>The IStructE Pai Lin Li Travel Award funded the author for an investigation into current practice precast concrete construction in the USA. The Federal Highways Administration (FHWA) in the USA has invested heavily in research into precast concrete construction through its Accelerated Bridge Construction (ABC) programme. The FHWA’s research has had a focus on innovative techniques for joining structural precast concrete elements together.<p>Grouted splice couplers and Ultra-High Performance Concrete are the two key enabling techniques that were investigated in this research. The replacement of 6 36m span bridges over Interstate 78 in Pennsylvania used these techniques and completed each bridge replacement in 40 days. This paper investigates the development of these techniques, the benefits they could have on the UK construction industry and what actions need to be taken to realise those benefits.


Author(s):  
Azita Azarnejad ◽  
Nathan Murdoch ◽  
Katherine Hikita ◽  
Jadwiga Kroman

<p>This project included the construction of a new three-span, 170 m-long steel box girder bridge to replace the existing St. George’s Island Bridge over the Bow River. The new bridge is composed of variable depth (arched), rectangular, steel box girders. Flood resiliency and sustainability were major considerations in the design of the bridge. The girders have a curved profile that allows for the majority of the superstructure to sit at least 1 m above the 1:100 year flood level. To minimize the work required over the river, full-depth, full-width, precast concrete deck panels were used. The panel-to-panel and panel-to-girder connections were made with Ultra-High-Performance Concrete (UHPC). Continuity of bridges with full-depth precast panels is usually provided by longitudinal post-tensioning. This was not preferred due to concerns about future deck rehabilitations. Therefore, the design relies on reinforcement splices for continuity. UHPC made it possible to transfer longitudinal forces in relatively short splice lengths. To verify the efficiency of these connections, some of the panels and connecting joints were instrumented with wireless strain gauges to monitor force transfer between adjacent panels. The paper includes a description of the bridge structure (girders and the precast deck panels) and the initial results of the strain monitoring.</p>


Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2269 ◽  
Author(s):  
Zhigang Zhang ◽  
Xiaoqing Xu

Field-cast ultra-high performance concrete (UHPC) connections are an innovative and prospective solution for combining full-depth precast concrete decks and steel girders. However, previous studies show that the slip capacity of stud shear connectors embedded in UHPC cannot meet the requirements for ductile connectors by Eurocode 4, which can reduce the resistance of steel and concrete composite members. In this study, the rubber-sleeved stud shear connector, which is a composite of ordinary stud and rubber sleeve, was adopted for the field-cast UHPC connections. Push-out tests were conducted to investigate the static and fatigue behavior of the rubber-sleeved stud shear connector as part of field-cast UHPC connections. Results of static tests showed that the rubber-sleeved stud shear connector has sufficient deformation capacity and its slip capacity is 1.5 times that of the ordinary stud shear connector. Compared to ordinary stud shear connectors, UHPC with high strength and stiffness has a relatively small effect on improving the shear strength and stiffness of rubber-sleeve stud shear connectors. Results of fatigue tests showed that the rubber-sleeved stud shear connector in UHPC has similar fatigue behavior to that in normal strength concrete. Though UHPC improves the restraint to the stud deformation, the influence of rubber sleeves is still decisive in determining the fatigue behavior of rubber-sleeve stud shear connectors. In addition, based on the results of strain gauges at stud roots, it was found that the crack initiation process consumes a small proportion of the fatigue life of rubber-sleeved stud shear connectors, which is about 5%.


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