RC Pipe Research Articles

An Analytical Solution of Chloride Transfer into RC Pipe Pile by Convection–Diffusion Effect Considering Time-Dependent Surface Chloride Concentration

An Analytical Solution of Chloride Transfer into RC Pipe Pile by Convection–Diffusion Effect Considering Time-Dependent Surface Chloride Concentration

An Experimental Investigation on the Dynamic Response of Buried RC Pipes Induced by Falling Impact

Unexpected ground impacts can seriously affect the stability and operational safety of buried pipelines. In this paper, a full-scale modeling test of the dynamic response of a buried concrete pipeline under falling rock impact based on dynamic sensor testing was conducted. A commercially available reinforced concrete pipeline, buried in a clayey soil site, was used, and a 50 kg concrete ball was used to investigate the impact above the pipeline. Considering the purpose of the test, the falling process of the concrete ball and the surface vibration velocity induced by the touchdown of the concrete ball were monitored using a high-speed camera and a vibration signal tester, respectively. The dynamic response signals of the pipe under surface impact were tested using strain gauges and earth pressure gauges combined with dynamic sensors such as dynamic signal tester, and the dynamic response law was analyzed. The experimental results will provide a basis for the design of the impact resistance of reinforced concrete pipes.

Seismic performance-based assessment of a RC pipe rack accounting for dynamic interaction

In contrast with common buildings, the limit-state assessment has not been applied to pipe-rack – piping systems yet, albeit the seismic vulnerability of critical pipes is rather high. The current engineering practice may design pipe rack – piping systems in a risk-inconsistent way due to the conservative acceptance criteria of seismic codes that keep pipes in the elastic range. Additionally, the response of pipes could become complex when considering differential displacements between internal supports, pipe edges and adjacent structures, which static methods may not describe efficiently. The design of a typical RC pipe rack – piping system in a code-consistent way resulted in two main outcomes. First, the piping required the increase of structural members cross-section, and secondly, the differential displacement was the main reason of pipe failure both in the longitudinal (unrestrained) as well as transverse direction. Finally, the performance-based assessment of this type of system demonstrated that the spectral acceleration is mildly more efficient and sufficient intensity measure than ground ones to describe the damage on piping. The observed mean annual frequency of exceedance was 57% smaller than the targeted value for the pipes, whereas the difference was considerably higher for the pipe rack. This outcome corroborated the conservativeness of codes and the risk-inconsistency between the structural and non-structural members.

Behavior of Buried RC Pipe Loaded Locally from Inner Surface

Behavior of Buried RC Pipe Loaded Locally from Inner Surface

Design and Simulation of RC Pipe Inspection Robot

In recent days, most of the industries are facing many problems to find out damages inside the pipe line. The pipe inspection Robot was made to avoid this problem and to find out the exact place of damage and to reduce the time of evaluating, repairing and managing of interior surface pipes. One of the most important requirements in inspection, repairing and maintenance of interior pipelines is the ability to monitor and evaluate interior surface of pipes. This research work deals with the modelling of robot for inspection, cleaning, maintenance to evaluate the interior surface piping systems. The design of pipe inspection robot has been done in NX Cad (UNIGRAPHICS).the robot is designed in such way that it can be used for different pipe diameters. The design and development of pipe inspection robot involves a mechanism which in turn is connected to two opposite sides of frame of links, joints and wheels. So by using this pipe inspection robot one can find out the exact location of damage inside the pipe, so that it will be very easy to resolve the problem.

Influence of Grout Strength and Residual Deformation on Performance of Rehabilitated RC Pipes

AbstractInserting a corrugated steel pipe (CSP) into an existing reinforced concrete pipe (RCP) is a common culvert rehabilitation technique in China. However, few studies have focused on the influ...

Theoretical approach for prediction of service life of RC pipe piles with original incomplete cracks in chloride-contaminated soils

This paper presents an analytical approach to predict the service life of RC pipe pile exposed to chloride environment. The proposed approach properly considers the unique features of the RC pipe pile involved in the entire deterioration stage, including the chloride ion diffusion in both the inner and outer covers of the pipe pile, the effects of original incomplete micro-cracks on the diffusion, and the restriction effects of earth pressure on generation of transverse cracks due to corrosion expansion. The RC pipe pile is assumed to reach the end of its service life when corrosion-induced penetrating cracks appear in the concrete, and the deterioration process is divided into the diffusion stage and the corrosion stage to determine the service life of the RC pipe pile. The diffusion of the chloride ion in the concrete cover with incomplete micro-cracks is modeled by a compound radial diffusion model, and the corresponding diffusion solution is developed to determine the time that the reinforcement begins to rust. The time from corrosion initiation to penetrating crack initiation is determined by relating the rate of rust production to the deformation of the RC pipe pile. The proposed diffusion solution is validated by an ABAQUS numerical model and extensive parametric studies are conducted to investigate the impacts of the width and depth of the original incomplete micro-crack, cover thicknesses, diameter of the reinforcement bar, concrete strength, pile end types, as well as the embedded depth on the chloride concentration profile and service life of the RC pipe piles. The proposed method provides a novel, reliable and practical approach for evaluating the service life of RC pipe pile served in chloride environments, which is of great significance for durability design and maintenance of RC pipe piles.

Investigation of the Load‐Sharing Theory of the RC Pipes Rehabilitated with Slip Liners

Slip‐lining is a preferred rehabilitation approach in the departments of transportation in China. Although the method is the most common rehabilitation technique, few research studies have been conducted on the mechanical behavior of a rehabilitated reinforced concrete pipe (RCP). A series of experiments were conducted on RCPs rehabilitated with a corrugated steel pipe (CSP), a steel pipe, a high‐density polyethylene (HDPE) pipe, and a shape steel bracket. The RCP rehabilitated with the CSP showed an increase in both the load‐carrying capacity (3.46 times greater than the RCP) and the stiffness (5.35 times greater than the RCP). The RCP rehabilitated with the steel pipe, HDPE pipe, and steel bracket exhibited an increase in the load‐carrying capacity (1.23, 1.50, and 1.31 times greater than the RCP, respectively), and the stiffness of these three pipes was not markedly changed. The slip‐lined pipe acts as a “pipe within a pipe” system. A “load‐sharing” theory was proposed in this study and provides estimates of the load‐carrying capacity of the slip‐lined pipes.

Hybrid fibre-reinforced geopolymer (HFRG) composites as an emerging material in retrofitting aging and seismically-deficient concrete and masonry structures

Fibre-reinforced polymer (FRP) systems have recently become popular in repairing concrete or masonry structures because of their inherent advantages. In spite of these benefits, FRPs have drawbacks having low fire resistance, poor environmental sustainability and incompatibilty with the substrate concrete. The effort to address these issues has led to the development of an emerging strain hardening cementitious (SHC) material using an inorganic polymer known as hybrid fibre-reinforced geopolymer (HFRG) composites. Compared with cement-based SHC composites, HFRG has better bond performance to concrete substrates, higher fire resistance, greater corrosion durability and helps to reduce CO2 emissions. This paper reviews the recent development of HFRG composites as an emerging repair material. Literature reveals that flowability of a fresh HFRG mixture decreases with increasing fibre content though still workable up to 2% fibre volume. Fibre synergy could result in 10–181% higher flexural toughness of geopolymer composites than when just using mono fibres. The application of HFRG composites to RC beams increased displacement ductility by to 263%. To date, there has been no reported field application of HFRG as a repair material though mono-fibre FRG has been field-applied as a strengthening material in large-diameter sewer RC pipes, RC culverts, RC sewerage manholes and dam surface improvement.

Impact of soil erosion voids on reinforced concrete pipe responses to surface loads

This paper discusses the results of controlled, full-scale laboratory experiments on 0.9 m (36 in.) internal diameter reinforced concrete pipes (RC pipes) in the presence of simulated erosion voids. This study introduces a novel, yet practical, experimental method to simulate erosion voids near buried pipes. Using this method, the paper focuses on capturing the circumferential moment changes experienced by a 0.9 m (36 in.) internal diameter RC pipe buried at 0.9 m depth as voids of different sizes (approximate cross-sectional areas of 0.16 m2 and 0.31 m2) develop beside it, which have not been investigated before in such tests. The tests were also repeated after the erosion voids were repaired using a low strength grout (∼2 MPa) to characterize it as a potential rehabilitation solution, and the moment changes were recorded. The presence of erosion voids resulted in an overall increase in bending moment with the invert moments being affected the most (e.g., 70% increase in the invert moment between the intact soil result and the small void result and a 26% increase in the invert moment between the intact soil result and the extrapolated large void results). While, grouting the erosion voids resulted in an overall improvement in the pipe responses, there was still a 50% increase in the invert moment between the intact soil result and the grouted small void result and a 22% change between the grouted large void and the intact soil tests. The large void tests showed that soil collapse is the dominant failure mechanism at high loads. Comparing the modified bedding factor values for pipes with different void sizes and void condition (pre- and post-grouting), the intact soil always featured the highest bedding factor, followed by grouted large void (approximately 22% reduction in bedding factor), grouted small void (approximately 36% reduction), and small void before grouting (approximately 39% reduction).

Experimental Investigation on Seismic Behavior of Steel Truss-RC Column Hybrid Structure with Steel Diagonal Braces

This paper aims to provide an experimental support on seismic performance evaluation of the steel braced truss-RC (reinforced concrete) column hybrid structure, which could be applied as the air-cooled supporting structural system in large-capacity thermal power plants located in strong earthquake prone regions. A series of pseudo-dynamic tests (PDTs) and quasi-static tests (QSTs) were performed on a 1/8-scaled sub-structure. The dynamic characteristics, lateral deformation patterns, deterioration behavior, hysteretic behavior and failure mechanisms were investigated. Test results showed that the first vibration mode is torsion, which is caused by the small torsional stiffness of this kind of hybrid structure. The lateral deformation shape is shear mode, and the drift ratio of the structure above the corbel is significantly less than that of the column below the corbel. Earthquake energy is mainly dissipated by the RC pipe columns where cracks mainly occurred at the bottom of column and lower part of corbel. The failure mechanisms were identified indicating that the steel braces improved the global stiffness and modified the load transfer mechanism. This study affirms that the steel braced truss-RC column hybrid structure has the sufficient ductility and good energy dissipation capacity to satisfy the design requirements in high seismic regions.

Evaluation of Cross-Sectional Stiffness along Axial Direction in Cracked RC Pipes

Evaluation of Cross-Sectional Stiffness along Axial Direction in Cracked RC Pipes

Large-Diameter Sewer Rehabilitation Using a Spray-Applied Fiber-Reinforced Geopolymer Mortar

AbstractTo assist utilities in making well-informed maintenance decisions, the EPA has developed an innovative technology demonstration program to evaluate technologies that have the potential to reduce costs and increase the effectiveness of the operation, maintenance, and renewal of aging water distribution and wastewater collection systems. Under this initiative, the performance of a new corrosion-resistant fiber-reinforced geopolymer mortar was evaluated. The fiber-reinforced geopolymer mortar was spray-applied to rehabilitate a preselected 49-m-long, 1,500-mm (160-ft-long, 60-in.) RC pipe (RCP) sewer main in Houston, Texas. Costing approximately $1,300–$2,000 per linear meter ($400–$600 per linear foot), a 84-mm-thick (3.3-in.) layer was sprayed uniformly onto the pipe’s interior, surpassing the minimum design thickness value of 48 mm (1.9 in.). The average 28-day compressive strength results of the coating were measured to be approximately 59 MPa (8,635 psi), which is above the manufacturer-stated c...

Service life prediction of cracked RC pipe piles exposed to marine environments

Cracks due to shrinkage, chemical reactions and weathering process occur unavoidably during construction and application of RC pipe piles. These cracks may be the main pathways through which chloride diffuses into the concrete and also can be one of the major reasons of steel corrosion in RC pipe piles exposed to marine environments. In the present paper, an analytical method for predicting the service life of cracked RC pipe pile with considering the effect of cracks on the chloride diffusion is presented. The governing equation of chloride diffusion into RC pipe pile is described and solved analytically by using the Bessel functions. The equivalent chloride diffusion coefficient is derived based on the partition of chloride diffusion through cracked RC pipe pile. The threshold chloride content is estimated from a wide review of previous experimental studies. Comparisons of analytical results with experimental data are conducted to establish the validity of the proposed analytical method. Furthermore, an application of the analytical method is demonstrated by predicting service life of cracked RC pipe piles exposed to marine environments. The analysis results demonstrate the importance of considering the effect of cracks for accurate prediction of service life in RC pipe piles exposed to marine environments.

Large-Diameter Sewer Rehabilitation Using a Fiber-Reinforced Cured-in-Place Pipe

AbstractDespite the use of trenchless methods in sewer rehabilitation for over 40 years, a lack of knowledge on the performance of emerging technologies is still a critical need in the sewer infrastructure industry. This has led to aging water infrastructure research organizations to develop rehabilitation technology demonstration programs. The results from these programs are intended to enhance the industry’s awareness of available technologies and their capabilities. One specific scenario of interest is the rehabilitation of large-diameter sewer mains. This paper describes the demonstration of an innovative fiber-reinforced composite cured-in-place pipe technology used to rehabilitate 5,243 m (17,200 ft) of 2,400-mm (96-in.) RC pipe in Irving, Texas. This technology met the utility owner’s requirements and mechanical testing showed that the liner exceeded the minimum design requirements. A key take away from the project was the importance of proper planning. Careful attention is required to ensure prope...

Nonlinear Finite-Element Modeling Analysis of Soil-Pipe Interaction

The effect of dynamic compaction forces is ignored in the analysis and design of underground structures. Several failure cases have been reported in which longitudinal cracks are observed during installation and compaction processes. Because, in the current specifications, compacting forces are not considered as design parameters, this study aims at determining the effect of dynamic compaction forces on RC pipes of different sizes. Thus, complete nonlinear three-dimensional finite-element models of pipe and soil are developed and verified against full-scale experimental testing. Particularly, crack initiation and propagation are modeled and predicted. Finally, the effects of dynamic forces are identified on the RC pipe.