Field Investigation of Spalling in Bridge Decks with Partial-depth Precast Concrete Panel Systems Using Non-destructive Testing PDF Download

Author: Kandi Rebecca Wieberg
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 292

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"This study involved the investigation of the causes of spalling observed in several partial-depth precast prestressed bridge decks in the state of Missouri. Recently it has been observed that several bridges in Missouri with this type of construction have experienced spalling of concrete at the edges of the panels revealing an extreme condition of corrosion in the prestressing tendons, some to the point of rupture. Ground penetrating radar (GPR), which has been shown to be successful in bridge deck evaluation, was used to determine the relative condition of the prestressing tendons as well as the relative condition of the concrete throughout the deck in order to identify areas of cracking and corrosion. Particular techniques were used in an attempt to identify areas of delamination at the interface between the precast panels and cast-in-place topping slab, namely the acquisition of data from both the top and bottom deck surfaces as well as specialized data interpretation techniques. Core control and visual inspection were utilized to interpret and validate the GPR data. Half-cell, resistivity and rebound hammer testing was performed on bridge deck panels to determine the corrosion levels of the prestressing strands and material properties of the panels. Findings indicate that spalling in the PPC panels is the result of the penetration of water and chlorides through the reflective cracking in the CIP topping, to the interface between the CIP topping and the PPC panels, then through the PPC panels to the prestressing tendons located near the panel joints. Increased crack control in the CIP topping delays the onset of spalling at the panel joints. Most deterioration is occurring near the area of reflective cracking in the CIP topping and not in the area of concrete over the middle of the panels. Some delamination is occurring at the CIP topping and panel interface"--Abstract, leaf iii.

Author: Lesley Sneed
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages :

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"This research has examined spalling of several partial-depth precast prestressed concrete (PPC) bridge decks. It was recently observed that some bridges with this panel system in the MoDOT inventory have experienced rusting of embedded steel reinforcement and concrete spalling issues in the deck panels. The objectives of this research were to investigate the causes of spalling in precast-prestressed panels and propose cost-effective alternative solutions including improved design options for new construction, as well as suggest mitigation methods for existing deteriorated bridge decks. A survey of transportation agencies and a series of bridge deck investigations were conducted to determine the nature and causes of spalling. Panel deck system modifications were proposed and evaluated for potential use in new construction. These modifications were investigated in terms of structural performance and serviceability with respect to the current design. Panel deck system modifications evaluated included an increase in tendon side cover, the addition of fibers or corrosion inhibitor to the panel concrete mixture, an increase in reinforcement in the cast-in-place concrete topping, and the substitution of edge tendons with epoxy-coated steel or carbon fiber reinforced polymer tendons. Efficiency of the proposed solutions was examined and validated through fundamental laboratory studies and numerical simulations using finite element modeling. Finally, recommendations are provided for new and existing construction to mitigate the spalling problem"--Technical report documentation page.

Author: Mohsen A. Issa
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 278

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Book Description
A literature review concerning the objectives of the project was completed. A significant number of published papers, reports, etc., were examined to determine the effectiveness of full depth precast panels for bridge deck replacement. A detailed description of the experimental methodology was developed which includes design and fabrication of the panels and assembly of the bridge. The design and construction process was carried out in cooperation with the project Technical Review Panel. The major components of the bridge deck system were investigated. This includes the transverse joints and the different materials within the joint as well as composite action. The materials investigated within the joint were polymer concrete, non-shrink grout, and set-45 for the transverse joint. The transverse joints were subjected to direct shear tests, direct tension tests, and flexure tests. These tests exhibited the excellent behavior of the system in terms of strength and failure modes. Shear key tests were also conducted. The shear connection study focused on investigating the composite behavior of the system based on varying the number of shear studs within a respective pocket as well as varying the number of pockets within a respective panel. The results indicated that this shear connection is extremely efficient in rendering the system under full composite action. Finite element analysis was conducted to determine the behavior of the shear connection prior to initiation of the actual full scale tests. In addition, finite element analysis was also performed with respect to the transverse joint tests in an effort to determine the behavior of the joints prior to actual testing. The most significant phase of the project was testing a full-scale model. The bridge was assembled in accordance with the procedures developed as part of the study on full-depth precast panels and the results obtained through this research. The system proved its effectiveness in withstanding the applied loading that exceeded eight times the truck loading in addition to the maximum negative and positive moment application. Only hairline cracking was observed in the deck at the maximum applied load. Of most significance was the fact that full composite action was achieved between the precast panels and the steel supporting system, and the exceptional performance of the transverse joint between adjacent panels.

Author: John Robert Kintz
Publisher:
ISBN:
Category :
Languages : en
Pages : 252

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Horizontally curved girder bridges are often utilized for highway interchanges and other projects with restricted right-of-way. The large torsional demands caused by the girder geometry often require these systems to have extensive bracing, typically in the form of cross frames or diaphragms, to increase the torsional stiffness of the girder system during the construction phase. The most critical stage for the bracing is during the deck placement, when the noncomposite girders must resist the full construction load. Partial depth precast concrete panels (PCPs) are prestressed concrete panels used primarily as stay-in-place (SIP) formwork for straight girder systems. They are placed on full-length extruded bedding strips epoxied to the girder top flange, and the remaining depth of the deck is cast above. This is a time-efficient method of construction, and has become an attractive option due to ease of constructability and deck longevity. Although the panels have not been used on horizontally curved girder systems, there is a desire by bridge owners and contractors to use the forms in some curved girder applications. In addition to using the panels on curved girder applications, engaging the in-plane shear stiffness of the panels may lead to significant bracing in both straight and horizontally curved girder applications. A research investigation focused on measuring the behavior of PCPs acting as a shear diaphragm, as well as to develop an adequate connection between the PCPs and the girders was conducted at The University of Texas at Austin. Four PCP connection details were developed and tested at two different bedding strip heights. These connections were designed for a range of capacities, and in-plane shear load was applied until failure using a frame mechanism assembly. The experimental results showed that the connected PCPs had significant shear stiffness and strength, with the panels reaching shear capacities between 91 and 154 kips before failure depending on the connection detail that was utilized. A 46 to 70 percent increase in shear stiffness was also observed when the bedding strip height was reduced from 4 inches to 1⁄2 inch. All panels greatly exceeded the design capacity using the ACI design predictions, with 7 of 8 panels eventually failing due to concrete side face breakout. The eighth PCP failed from weld rupture in which the weld connecting the WT and the girder flange began to unzip.

Author:
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 75

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Book Description
Precast bridge deck panels can be used in place of a cast-in-place concrete deck to reduce bridge closure times for deck replacements or new bridge construction. The panels are prefabricated at a precasting plant providing optimal casting and curing conditions, which should result in highly durable decks. Precast panels can be either full-depth or partial-depth. Partial-depth panels act as a stay-in-place form for a cast-in-place concrete topping. This study investigated only the behavior of full-depth precast panels. The research described in this report had two primary objectives. The first was to develop a performance specification for the grout that fills the haunch between the top of the beam and the bottom of the deck panel, as well as the horizontal shear connector pockets and the panel-to-panel joints. Tests were performed using standard or modified ASTM tests to determine basic material properties on eight types of grout. The grouts were also used in tests that approximated the conditions in a deck panel system. Based on these tests, requirements for shrinkage, compressive strength, and flow were established for the grouts. It was more difficult to establish a test method and an acceptable performance level for adhesion, an important property for the strength and durability of the deck panel system. The second objective was to quantify the horizontal shear strength of the connection between the deck panel and the beam prestressed concrete beams. This portion of the research also investigated innovative methods of creating the connection. Push-off tests were conducted using several types of grout and a variety of connections. These tests were used to develop equations for the horizontal shear strength of the details. Two promising alternate connections, the hidden pocket detail and the shear stud detail, were tested for constructibility and strength. The final outcome of this study a set of recommendations for the design, detailing, and construction of the connection between full-depth precast deck panels and prestressed concrete I-beams. If designed and constructed properly, the deck panel system is an excellent option when rapid bridge deck construction or replacement is required.

Author: Nabil F. Grace
Publisher:
ISBN:
Category : Concrete beams
Languages : en
Pages : 229

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Book Description
This study developed a procedure to identify concrete bridge decks that are exhibiting the characteristics associated with falling concrete. Field exploratory work on reinforced concrete bridge decks was supported by analytical and laboratory investigations. The field work included visual inspection, non-destructive tests, and sampling of full-depth cores and powder samples from the bottom of the bridge deck. Chief variables assessed were the chance of corrosion by the half-cell potential, chloride content at the location of the bottom reinforcement, and the concrete pH level. The chloride diffusivity was estimated from the chloride profile. The laboratory investigation was performed on bridge deck beams. The beams were constructed from concrete containing chloride levels known to cause corrosion as well as from a control concrete. Beams were subjected to freeze-thaw or saltwater followed by repeated loading to simulate field conditions. The following characteristics were quantified: chance of corrosion, corrosion rate, chloride content, flexural response as a function of environmental exposure and repeated loads, and ultimate strength. The size of the porous zone around the reinforcement was determined using an environmental scanning electron microscope. Finally, a strategy was developed to assess if a bridge deck exhibited the characteristics associated with falling concrete. The strategy included visual inspection of cracking and spalling, assessment of chance of corrosion, chloride content, and pH levels. If any of these measures exceed critical levels a service life calculation needs to be performed. Based on existing mathematical models, the time to corrosion initiation and time to corrosion cracking can be predicted. The resulting time is then compared to the age of the bridge. From this information proper planning for future repair needs can be made.

Author: Mark D. Whittemore
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 46

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Author:
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 68

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Experimental tests were performed at Virginia Tech to investigate transverse panel-to-panel connections and horizontal shear connector block-outs for full-depth precast concrete bridge deck panels. The connections were designed for a deck replacement project for a rural three-span continuous steel beam bridge in Virginia. Two reinforced and four post-tensioned connections were designed and tested in cyclical loading. Each connection was tested on a full-scale, two-beam setup in negative bending with a simulated HS-20 vehicle. The block-outs for the horizontal shear connections were also scrutinized during construction and testing. Several surface treatments were investigated to determine the best strategy to limit cracking and leakage at the grout-concrete interface. The strain profile, cracking patterns, and ponding results are presented for all specimens. The reinforced connections and two post-tensioned connections with 167 psi initial stress experienced cracking and leaked water by the end of the cyclic loading regime. In two connections post-tensioned with an initial compressive stress of 340 psi, the tensile stress in the deck under full live load remained below approximately 3√(f'c). These transverse connections did not leak water, did not have full-depth cracking, and maintained a nearly linear strain distribution throughout the design life. Full-depth deck panels may be effectively used on continuous bridges if post-tensioning force is applied to the transverse connections to keep the total tensile stress (remaining prestress minus live load stress) below 3√(f'c) . The block-outs with a sand-blasted surface or an epoxy primer combined with a grout that met the requirements recommended by Scholz et al. (2007) had only slight water leakage, and had smaller cracks at the grout-concrete interface than the control samples. These surface treatments are recommended for best long-term performance.

Author: Wesley J. Cook
Publisher:
ISBN: 9781124478500
Category : Bridges
Languages : en
Pages : 96

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Book Description
The Utah Department of Transportation (UDOT) has implemented the use of precast concrete panels for bridge deck construction. A bridge utilizing these panels as a reconstruction method was decommissioned three years after the new deck installation, due to unrelated matters. Two sections of this bridge were salvaged and sent to Utah State University (USU) for destructive testing. Each bridge section consisted of two built-up steel plate girders intact with the precast concrete deck panels. The precast panels were designed and constructed to achieve full composite action between the deck and built-up steel plate girders through the use of Nelson shear studs. Additionally, the precast panels span the transverse direction and as such have a transverse joint. Historic data has shown the transverse joint to be an area of concern for the functionality of the structural system. Flexure, beam shear, and punching shear of the deck ultimate capacities were compared to those calculated in accordance to the AASTHO Load and Resistance Factor Design (LRFD) Bridge Design Specifications. Various experimental tests considered the affects of the transverse joint on the elastic and plastic capacities and code adherence. Nine destructive tests were performed. The Nelson shear studs were found to be capable of achieving the ultimate capacities of all three types of performed tests and therefore a significant level composite action was attained throughout the experimental tests. The transverse joints show a slight decrease in flexural elastic capacity, no measurable influence on flexural plastic capacity and beam shear ultimate capacity, and a 40% decrease to ultimate punching shear capacity to the deck compared to punching shear capacity without a transverse joint.

Author: David M. Gee
Publisher:
ISBN:
Category :
Languages : en
Pages : 108

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Book Description
This study looks at the removal of longitudinal rebar splicing when sufficient longitudinal post-tensioning is provided for full-depth precast deck panels for simply supported bridges. Full-depth precast prestressed concrete deck panels are high quality plant produced pretensioned panels. They are often post-tensioned at the site to provide an average net compression in the joint of at least 250 psi due to effective prestress. This is to ensure adequate transfer of load as truck wheels pass over the joint. This net compression on the transverse joint is not explicitly clear by the AASHTO LRFD Bridge Design Specifications. Based on this section, it is unclear if the use of post-tensioning that provides a net compression of at least 250 psi at the joint, due to effective prestress, still requires the coupling of rebars over the transverse joint. However, in cast-in-place deck construction, no longitudinal post-tensioning is generally introduced and no transverse joint is required. It is a requirement of the ASSHTO LRFD Bridge Design Specifications that secondary reinforcement be placed continuously along the direction of traffic. Following the empirical deck design in AASHTO, two-thirds of the primary transverse reinforcement should be provided for secondary longitudinal reinforcement. The problem is observed when a number of designers insist on strictly following the code for full-depth precast deck panel designs without considering the impact of longitudinal post-tensioning and naively emulating cast-in-place practice without taking full advantage of precast concrete. Although providing secondary reinforcement for each precast panel is possible, the number of splices and the number of pockets for field splicing due to these extended bars become a significant challenge to this type of construction. By using sufficient net compression at the joint, rebar splicing can be removed. The objective of this research is to investigate the post-tensioning level required to eliminate rebar splices in transverse joints for full-depth precast deck panels. Two full scale full-depth precast deck panels were post-tensioned to multiple levels varying the net compression at the joint between 100 to 350 psi. Static tests with a point load simulating one-wheel load of the 32-kip axle multiplied by the dynamic allowance factor (1.75 for the deck joint) was applied to the panel-to-panel connection joint for various post-tensioning levels. The test results show that when a net compression of at least 300 psi is applied at the transverse joint, rebar splicing is not needed. This is supported by the lack of cracking that occurs when applying the 32-kip loading along the joint. Testing along the longitudinal joint was also conducted as a separate research topic, and some of the results are presented. The main objective of this testing was to determine the viability of using a staggered rebar joint with a minimal joint width. This was accomplished by using ultra-high-performance concrete (UHPC) and self-consolidating concrete (SCC) with steel fibers to enhance the ductility and strength of the joint. By using a joint that gives sufficient development length of the bars, which is shorter for fiber reinforced concretes, it is shown that the joint detailing is adequate for service loadings.