scholarly journals An Evaluation Method for Effective Prestress of Simply Supported Prestressed Concrete Beams with Breathing Cracks

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Wenlong Guo ◽  
Peng Liang ◽  
Hexu Liu ◽  
Y. Frank Chen ◽  
Xiaojin Zhao
Keyword(s):  
Prestressed Concrete ◽  
Evaluation Method ◽  
Concrete Bridges ◽  
Stress Change ◽  
Test Results ◽  
Load Curve ◽  
Change Rate ◽  
Simply Supported ◽  
Curve Method ◽  
Precast Prestressed Concrete

Loss of effective prestress and accurate detection of actual stress in existing precast prestressed concrete bridges are two major challenges in the bridge industry. In this respect, this research aims at an improved method for the critical decompression moment (DM) test of cracked sections depending on the stress change rate of tensile rebars. A calculation method for total effective prestress of prestressing strands in the tensile region is derived with the assumption of the plane section and pre-decompression elastomer. The proposed method is verified by laboratory tests on beams and numerical analysis and by addressing effective prestress issues of existing simply supported beams. The determination results of the critical decompression state show that the proposed method (i.e., the stress change rate of tensile rebars-load curve) is more sensitive and reasonable than the traditional stress increment, i.e., load curve method. The evaluation results of the total effective prestress are more reasonable than the traditional method based on the steel stress relief hole technique or frequency test results. Compared with the existing methods for estimating the prestress using the mid-span deflection or crack width, the proposed method is more reasonable in theory and calculation. It provides a guide for the evaluation and reinforcement of aging bridges.

scholarly journals Corrosion Detection in PSC Bridge Tendons Using Kernel PCA Denoising of Measured MFL Signals

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 5984
Author(s):  
Chang Kook Oh ◽  
Changbin Joh ◽  
Jung Woo Lee ◽  
Kwang-Yeun Park
Keyword(s):  
Prestressed Concrete ◽  
Evaluation Method ◽  
Principal Component ◽  
Concrete Bridges ◽  
Kernel Principal Component Analysis ◽  
Cross Sectional ◽  
Measuring Device ◽  
Prestressed Concrete Bridges ◽  
Significant Damage ◽  
Non Destructive

The construction of prestressed concrete bridges has witnessed a steep increase for the past 50 years worldwide. The constructed bridges exposed to various environmental conditions deteriorate all along their service life. One such degradation is corrosion, which can cause significant damage if it occurs on the main structural components, such as prestressing tendons. In this study, a novel non-destructive evaluation method to incorporate a movable yoke system with denoising algorithm based on kernel principal component analysis is developed and applied to identify the loss of cross-sectional area in corroded external prestressing tendons. The proposed method using denoised output voltage signals obtained from the measuring device appears to be a reliable and precise monitoring system to detect corrosion with less than 3% sectional loss.

scholarly journals Application of Large Prestress Strands in Precast/Prestressed Concrete Bridges

2020 ◽  
Vol 6 (1) ◽  
pp. 130-141
Author(s):  
Amin K Akhnoukh
Keyword(s):  
Prestressed Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Large Diameter ◽  
Concrete Bridges ◽  
Bridge Construction ◽  
Prestressed Concrete Bridges ◽  
Research Findings ◽  
Flexure Capacity ◽  
Precast Prestressed Concrete

The objective of this research is to investigate the advantage of using large-diameter 0.7-inch (18 mm) strands in pretention applications. Large-diameter strands are advantageous in bridge construction due to the increased girders capacity required to sustain exponential increase in vehicle numbers, sizes, and weights. In this research, flexure capacity of girders fabricated using 0.7-inch (18 mm) diameter strands will be calculated and compared to bridge capacities constructed using smaller strands. Finally, two similar bridge sections will be designed using 0.6-inch (15 mm) and 0.7-inch (18 mm) diameter strands to quantify the structural advantages of increased strand diameter. The research findings showed that a smaller number of girders is required for bridge construction when larger strands are used. Four girders are required to design the bridge panel using high performance concrete and large diameter strands, as compared to 6 girders required when regular concrete mix designs and normal size strands are used. The advantages of large strands and high-performance concrete mixes include expedited construction, reduced project dead loads, and reduced demand for labor and equipment. Thus, large strands can partially contribute to the improvement of bridge conditions, minimize construction cost, and increase construction site safety.

Short to Medium Span Precast Prestressed Concrete Bridges in Japan

PCI Journal ◽  
1994 ◽  
Vol 39 (2) ◽  
pp. 74-100 ◽  
Author(s):  
Takashi Yamane ◽  
Maher K. Tadros ◽  
P. Arumugasaamy
Keyword(s):  
Prestressed Concrete ◽  
Concrete Bridges ◽  
Prestressed Concrete Bridges ◽  
Precast Prestressed Concrete

INTRODUCTION TO CAMBER CONTROL, PRESTRESSED CONCRETE BRIDGE GIRDERS

2014 ◽  
Vol 4 (2) ◽  
pp. 535-538
Author(s):  
Akhil Ratra ◽  
Kuldeep Singh ◽  
Sandeep Dhillon
Keyword(s):  
Prestressed Concrete ◽  
Concrete Bridges ◽  
Bridge Girders ◽  
Concrete Bridge ◽  
Ultimate Capacity ◽  
Simply Supported ◽  
Allowable Stresses ◽  
Bridge Girder ◽  
Common Problems ◽  
Prestressed Concrete Bridge

When designing a bridge, serviceability usually controls and is a more important factor than the ultimate capacity of the bridge or the allowable stresses. Therefore, the behaviour of the bridge girder deflection and camber must be predicted as accurately as possible. Therefore, excessive camber has become one of the most common problems when constructing concrete bridges. Different methods have been developed to overcome this problem. The most common and widely used is using haunch with adjustable pedestals to overcome the excessive camber. However, this method has limitations that must be considered. Therefore, this study is evaluating the effectiveness of using post tensioning jacking strands at the top flange of simply supported bridge girders to reduce the excessive camber and make it equal to the design camber.

scholarly journals Effects of Blast Loading on Prestressed Girder Bridges

2012 ◽  
Vol 19 (1) ◽  
pp. 1-18 ◽  
Author(s):  
William F. Cofer ◽  
Debra S. Matthews ◽  
David I. McLean
Keyword(s):  
Prestressed Concrete ◽  
Critical Role ◽  
Blast Loading ◽  
Highway Bridges ◽  
Element Model ◽  
Concrete Bridges ◽  
September 11Th ◽  
Girder Bridges ◽  
Bridge Model ◽  
Precast Prestressed Concrete

Since the events of September 11th, increased attention has been given to the effects of blast loading on structures. Bridges are especially important due to their potentially critical role in the economy and for emergency response. Prestressed concrete highway bridges are very common, representing 11 percent of state bridges nationwide. Yet, very little is known about how prestressed concrete bridges respond to blast loading.A finite element model of a precast, prestressed concrete girder was created and validated with two experimental blast tests. It was found that for an explosive event above or below the girder, numerical and empirical results were consistent.The girder model was expanded to a four-girder, simple-span bridge model. Three different scenarios were examined at the midspan of the bridge: a blast between two girders above the deck, a blast centered on a girder above the deck, and a blast beneath the deck. The two load cases from above resulted in highly localized damage with the possibility for other sections of the bridge to be immediately reopened after the event. Results for the load case from below indicate that the slab will be heavily damaged but the girders will remain intact.

scholarly journals Development of Constitutive Model for Precast Prestressed Concrete Segmental Columns

2016 ◽  
Vol 2016 ◽  
pp. 1-11
Author(s):  
M. Hafezolghorani Esfahani ◽  
F. Hejazi ◽  
R. Vaghei ◽  
E. Nikbakht ◽  
D. C. J. Tze
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Prestressed Concrete ◽  
Constitutive Models ◽  
Element Model ◽  
Research Area ◽  
Concrete Bridges ◽  
Dimensional Finite Element ◽  
Finite Element Package ◽  
Precast Prestressed Concrete

The interest of using precast segmental columns in construction of concrete bridges has significantly increased in recent years. One research area of concrete bridges is the application of Precast Prestressed Concrete Segmental (PPCS) Column in any structural analysis software or FE program code. Modeling a PPCS column, which consists of various materials with interaction between them, is complicated and time-consuming. This research attempts to formulate the stiffness matrix of PPCS columns in order to form the constitutive model in linear form to evaluate the response of the columns. A two-dimensional finite element model is presented in the finite element package ANSYS. Parametric studies are conducted by finite element models to verify the constitutive models for the PPCS column with a different number of concrete segments. Comparison between the constitutive model and the FE program results indicates that the constitutive model is accurate enough to predict the deformation of the PPCS columns.

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