Full scale test of a PC bridge to calibrate assessment methods

2021 ◽  
Author(s):  
Niklas Bagge ◽  
Jonny Nilimaa ◽  
Silvia Sarmiento ◽  
Arto Puurula ◽  
Jaime Gonzalez-Libreros ◽  
...  
Keyword(s):  
Prestressed Concrete ◽  
Structural Response ◽  
Sensitivity Study ◽  
Assessment Method ◽  
Full Scale ◽  
Concrete Bridges ◽  
Fractional Factorial ◽  
Fe Model ◽  
Load Carrying ◽  
Existing Bridges

<p>In this paper, experiences on the development of an assessment method for existing bridges are presented. The method is calibrated using the results of full-scale testing to failure of a prestressed bridge in Sweden. To evaluate the key parameters for the structural response, measured by deflections, strains in tendons and stirrups and crack openings, a sensitivity study based on the concept of fractional factorial design is incorporated to the assessment. Results showed that the most significant parameters are related to the tensile properties of the concrete (tensile strength and fracture energy) and the boundary conditions. A finite element (FE) model in which the results of the sensitivity analysis were applied, was able to predict accurately the load-carrying capacity of the bridge and its failure mode. Two additional existing prestressed concrete bridges, that will be used to improve further the method, are also described, and discussed.</p>

scholarly journals Assessment of Mechanical Properties of Corroded Prestressing Strands

2020 ◽  
Author(s):  
Chi-Ho Jeon ◽  
Cuong Duy Nguyen ◽  
Chang-Su Shim
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Prestressed Concrete ◽  
Critical Issue ◽  
Concrete Bridges ◽  
Structural Behavior ◽  
Maximum Deformation ◽  
Prestressing Steel ◽  
Governing Factor ◽  
Existing Bridges

The corrosion of prestressing steel in prestressed concrete bridges is a critical issue for bridge maintenance. To assess structures with corroded strands, it is necessary to define the mechanical properties of the strands and their influence on the structural behavior. In this study, corroded strands are taken from external tendons in existing bridges and tested to define the effects of corrosion on the tensile properties of the strand. Empirical equations for the tensile strength and ductility of the corroded strand are proposed using test results. The most corroded wire governs the mechanical properties of the strand. Experiments on prestressed concrete beams with a single corroded strand are conducted to investigate the structural behavior. A reduction in the flexural strength and maximum deformation is observed from the experiment. According to the section loss of a wire in a strand and its location in a beam, the flexural capacity can be evaluated using the proposed equation. The reduced ultimate strain of the corroded strand can be the governing factor of the flexural strength.

Reliability-Based Assessment of Safe Excavation Pressure for Dented Pipelines

2020 ◽  
Author(s):  
Chike Okoloekwe ◽  
Matthew Fowler ◽  
Amandeep Virk ◽  
Nader Yoosef-Ghodsi ◽  
Muntaseer Kainat
Keyword(s):  
Numerical Models ◽  
Mechanical Damage ◽  
Structural Response ◽  
Assessment Method ◽  
Full Scale ◽  
Burst Pressure ◽  
Operating Pressure ◽  
Element Analysis ◽  
Fea Model ◽  
Full Scale Tests

Abstract Dents in a pipe result in alteration of its structural response when subjected to internal pressure. Excavation activities further lead to change in load and boundary conditions of the pipe segment which may exacerbate the stress state within the dented region. Depending on the severity of a dent, excavation under full operating pressure may lead to failure, injuries or fatalities. Although uncommon, an incident has been reported on a gas pipeline where a mechanical damage failed during investigation leading to one death and one injury [10]. While current pipeline regulations require that operators must depressurize a line to ensure safe working conditions during repair activities, there are no detailed provisions available in the codes or standards on how an operator should determine such a safe excavation pressure (SEP). As a result, the safe excavation process of dents has received attention in the industry in recent years. A detailed review of the recent research on dent SEP showed that the current recommendations are primarily dependent on one of two aspects: careful assessment of inline inspection (ILI) data, or a fitness for service (FFS) assessment of the dent feature leveraging numerical models. Enbridge Liquid Pipelines had previously demonstrated a feature specific assessment approach which incorporated both ILI data and finite element analysis (FEA) to determine the SEP. This assessment also accounted for uncertainties associated with material properties and ILI tool measurement. In the previous publication, the authors demonstrated a methodology for assessing the SEP of dents at a conceptual level from both deterministic and reliability-based standpoints. In this paper, a validation study has been performed to compare the results of fracture mechanics based FEA models against ten full scale burst tests available in literature. The study showed good agreement of the burst pressure of dent-crack defects predicted by FEA models with those observed in the full-scale tests. The assessment method is further streamlined by incorporating the API 579 [14] Failure Assessment Diagram (FAD) method on an uncracked FEA model as opposed to explicitly incorporating the crack geometry in the FEA model. The results of FEA in conjunction with FAD are compared with the full-scale tests to ensure accuracy and conservatism of burst pressure prediction. A reliability-based approach is then designed which accounts for the uncertainties associated with the analysis. A case study is presented where the reliability-based SEP assessment method has been implemented and feature specific SEP has been recommended to ensure target reliability during excavation.

scholarly journals Behavior of Strengthened Composite Prestressed Concrete Girders under Static and Repeated Loading

2017 ◽  
Vol 2017 ◽  
pp. 1-13
Author(s):  
Abbas AbdulMajeed Allawi
Keyword(s):  
Prestressed Concrete ◽  
Experimental Tests ◽  
Full Scale ◽  
Repeated Loading ◽  
Test Results ◽  
Concrete Girders ◽  
Load Carrying ◽  
Prestressed Concrete Girders ◽  
Aashto Lrfd ◽  
Analysis Models

The use of external posttensioning technique for strengthening reinforced concrete girders has been considerably studied by many researchers worldwide. However, no available data are seen regarding strengthening full-scale composite prestressed concrete girders with external posttensioned technique under static and repeated loading. In this research, four full-scale composite prestressed I-shape girders of 16 m span were fabricated and tested under static and repeated loading up to failure. Accordingly, two girders were externally strengthened with posttensioned strands, while the other two girders were left without strengthening. The experimental tests include deflection, cracking load, ultimate strength and strains at midspan, and loading stages. Test results were compared with the design expressions mentioned in AASHTO LRFD specifications and ACI 318-2014 code. Also, a nonlinear analysis was conducted using the finite element method (FEM). The presented analysis models were verified by comparing the model results with test results. The general theme abstracted from both experimental tests and numerical analysis reflects that the performance and procedure of strengthening with external prestressing of girders were found to be effective in increasing the load carrying capacity of the strengthened girders.

Damage Assessment of One Prestressed Concrete Bridge after Fire

2012 ◽  
Vol 256-259 ◽  
pp. 2729-2734 ◽  
Author(s):  
Kai Xiang ◽  
Guo Hui Wang ◽  
Hua Xin Liu
Keyword(s):  
Prestressed Concrete ◽  
Damage Assessment ◽  
Assessment Method ◽  
Concrete Bridges ◽  
Concrete Bridge ◽  
Hollow Core ◽  
Plate Girders ◽  
Prestressed Concrete Bridges ◽  
Prestressed Concrete Bridge ◽  
Historical Sketch

The assessment method of fire-damaged concrete bridge with prestressed hollow core plate girders was presented in this paper. The historical sketch of assessment of fire-damaged concrete structures was briefly introduced. One fire-damaged concrete bridge with prestressed hollow core plate girders was shown as an example. The process of assessment of fire-damaged concrete bridge with prestressed hollow core plate girders was provided. According to the assessment results, methods of repair and strengthening were presented for different fire-damaged level of prestressed hollow core plate girders. The research results could help expand use of fire-damaged assessment and repair of prestressed concrete bridges.

scholarly journals Gamma prediction models for long-term creep deformations of prestressed concrete bridges

2017 ◽  
Vol 23 (6) ◽  
pp. 681-698 ◽  
Author(s):  
Alfred STRAUSS ◽  
Roman WAN-WENDNER ◽  
Anja VIDOVIC ◽  
Ivan ZAMBON ◽  
Qiang YU ◽  
...  
Keyword(s):  
Prestressed Concrete ◽  
Prediction Models ◽  
Numerical Models ◽  
Structural Response ◽  
Influential Factors ◽  
Concrete Bridges ◽  
Gamma Process ◽  
Prestressed Concrete Bridges ◽  
Creep And Shrinkage

For long-span bridges as well as statically indeterminate frame structures it is essential to implement efficient and realistic prediction models for the long-term processes of concrete creep, shrinkage, and steel relaxation. In order to systematically study the main influential factors in bridge deflection measurements a probabilistic analysis can be per­formed. Due to the associated computational costs such investigations are limited. The predictions based on the highly scattered input parameters are associated with uncertainties. There is interest in alternative prediction models decou­pled from complex analytical and computationally expensive numerical models, using measured structural responses. A gamma process is an example of such an alternative method. This process is suitable for capturing evolving structural response quantities and deterioration mechanisms like crack propagation, corrosion, creep, and shrinkage, as reported in Ohadi and Micic (2011). The objective of this paper is to illustrate the use of gamma process approaches for the pre­diction of the creep and shrinkage performance of prestressed concrete bridges. The presented approaches incorporate uncertainties and make predictions more reliable with the help of structural health monitoring (SHM) data. The creep-shrinkage response of a prestressed box girder bridge serves for the calibration and evaluation of the considered gamma process approaches.

Bridges Tested to Failure in Sweden

2018 ◽  
Author(s):  
Björn Täljsten ◽  
Thomas Blanksvärd ◽  
Gabriel Sas ◽  
Niklas Bagge ◽  
Jonny Nilimaa ◽  
...  
Keyword(s):  
Prestressed Concrete ◽  
Carrying Capacity ◽  
Load Carrying Capacity ◽  
The Real ◽  
Existing Structures ◽  
Steel Truss Bridge ◽  
Standard Code ◽  
Load Carrying ◽  
Existing Bridges ◽  
Truss Bridge

Five bridges of different types have been tested to failure and the results have been compared to analyses of the load-carrying capacity using standard code models and advanced numerical methods. The results may help to make accurate assessments of similar existing bridges. There it is necessary to know the real behaviour, weak points, and to be able to model the load-carrying capacity in a correct way.<p> The five bridges were: (1) a strengthened one span concrete road bridge - Stora Höga ; (2) a one span concrete rail trough bridge loaded in fatigue – Lautajokk; (3) a two span strengthened concrete trough railway bridge - Övik; (4) a one span railway steel truss bridge -Åby; and (5) a five span prestressed concrete road bridge - Kiruna. The unique results in the paper are the experiences of the real failure types, the robustness/weakness of the bridges, and the accuracy and shortcomings/potentials of different codes and models for safety assessment of existing structures.

The Connection Form of New-Built and Existing Bridge Effect on Transverse Distribution of Vehicle Load

2011 ◽  
Vol 250-253 ◽  
pp. 3008-3011
Author(s):  
Jihao Chen ◽  
Shun Bo Zhao ◽  
Ji Tao Yao
Keyword(s):  
Prestressed Concrete ◽  
Concrete Bridges ◽  
Connection Form ◽  
Transverse Distribution ◽  
Prestressed Concrete Bridges ◽  
Vehicle Load ◽  
Transverse Joint ◽  
Working Together ◽  
Vehicle Loads ◽  
Existing Bridges

Connection the upper components and disconnection the other components is widely used in the expressway hollow slab bridge widening and reconstruction. How to design the transverse joint between newly-built and existing bridges is a key problem in the renovation of prestressed concrete bridges. In this paper, combined with a freeway widening project, 2 kinds of different connection forms were compared by their transverse distribution influence lines, which were calculated by finite element method. The results show that the new and old bridges are working together after widening, which makes vehicle loads of the slabs of the old bridge are reduced, especially the side slab of old bride which was next to the slab of newly-built bridge dropped by nearly 50%. So the bridge widening strengthens the safety of old bridge. And the weak connection of the bridge is always the connection of newly-built bridge and existing bridge, which is accorded with practical situation. So the particular attention should be given to the connection. It provides a basis for widening the old bridge and a reference for widening and maintenance the same kind of bridges.

Experimental and Numerical Studies of the Plastic Behavior of Large Structural Grillages Subjected to Ice Loads

2016 ◽  
Author(s):  
Hyunmin Kim ◽  
John Dolny ◽  
Claude Daley
Keyword(s):  
Structural Response ◽  
Structural Deformation ◽  
Plastic Behavior ◽  
Fe Model ◽  
Numerical Studies ◽  
Load Carrying ◽  
Significant Research ◽  
Ice Loads ◽  
Symmetric Loading ◽  
Ultimate Load Carrying Capacity

Significant research efforts have been carried out to investigate the plastic behavior of grillage structures. However, most experimental work has used steel or other rigid indenters rather than real ice. The tests therefore showed certain structural response behavior that may occur differently if subjected to ice loads. In this study, ice samples were used to load the structure rather than rigid indenters. This allowed for investigation into structural deformation considering the failure of ice. Two large grillages were prepared and tested. The first grillage tests were intended to study the ultimate load-carrying capacity when subjected to central and symmetric loading. The second grillage was tested to study the influence of variable ice loading positions along a single frame. A finite element (FE) model was developed to analyze the experiments numerically. The load-deflection curves and deformation shapes measured by the MicroScribe® were used to validate the numerical results.

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