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- Täljsten, Björn, 1961-, et al.
(författare)
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Assessment of prestressed concrete bridges - challenges
- 2020
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Ingår i: IABSE Symposium, Wroclaw 2020. - Zürich : International Association For Bridge And Structural Engineering (IABSE). ; , s. 487-494
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Konferensbidrag (refereegranskat)abstract
- Prestressed concrete bridges are important parts of our infrastructure. They are susceptible to different kinds of deterioration processes. Examples of damages and deficiencies are cracking, corrosion, voids, bond loss, reduction of cover layer, delamination, fatigue and loss of stiffness and strength. This necessitates methods to continuously assess their condition in order to avoid problems that might lead to shorter service life or reduction of structural integrity. Many of the existing prestressed bridges in Europe are now approaching their design life length. However, with proper and continuous inspection, monitoring and assessment, we may plan proactive maintenance and the structural safety can be assured or – if necessary - increased. This will save both money and decrease the environmental impact of the structure.
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| 6. |
- Plos, Mario, 1963, et al.
(författare)
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Structural assessment of concrete railway bridges
- 2008
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Ingår i: Bridge Maintenance, Safety, Management, Healt Monitoring and Informatics. - 9780415468442 ; , s. 705-
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Konferensbidrag (refereegranskat)abstract
- The work presented provides enhanced assessment methods that are able to prove higher load-carrying capacities and longer fatigue lives for existing concrete railway bridges. It was performed as a part of the EU-project Sustainable Bridges. The results are implemented in the Guideline for Load and Resistance Assessment of existing European Railway Bridges, see SB-LRA (2007) and are reported in detail in a background document, see SB4.5 (2007). The work presents improved methods for the determination of in-situ material properties, for deterministic as well as probabilistic assessments. Advanced methods for structural analysis are presented, e.g. regarding combined shear, torsion and bending interaction. Recommendations are given regarding redistribution of sectional moments and forces obtained from linear finite element analysis. One main objective was to facilitate the use of non-linear analysis for structural assessment. This provides the greatest potential to discover any additional sources for load-carrying capacity, and gives a better understanding of the structural response. Another main objective was to provide methods to assess the remaining structural resistance of deteriorated concrete bridges. Recommendations are given on the effect of corrosion and a methodology is presented for assessment of remaining fatigue life, with emphasis on short-span bridges and secondary elements.
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| 7. |
- Nilforoush, Rasoul, et al.
(författare)
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Numerical and Experimental Evaluations of Influence of Member Thickness, Anchor Head Size, and Surface Reinforcement on Tensile Breakout Capacity of Anchor bolts
- 2017
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Ingår i: Connections between Steel and Concrete. - Stuttgart. - 9783945773062 ; , s. 752-764
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Konferensbidrag (refereegranskat)abstract
- The influence of member thickness, size of anchor head, and orthogonal surface reinforcement on the tensile breakout capacity of cast-in-place headed anchors in uncracked concrete was studied both numerically and experimentally. The aim of this paper is to form a background for developing improved methods for the design of new fastenings as well as the assessment of current anchorages in practice. For this purpose, anchor bolts at various embedment depths (hef=50–500 mm) were simulated in plain and reinforced concrete members of various thicknesses (H=1.5–5.0∙hef). Three different head sizes of anchor bolts (i.e. small, medium and large) were also considered at each anchor embedment depth. Furthermore, to verify the numerical findings, a series of anchor pullout tests were carried out at which the testing parameters were similar to those in the numerical study.Numerical and experimental results show that the tensile breakout capacity of anchor bolts increases by increasing the member thickness or if surface reinforcement is present. The anchorage capacity further increases with increasing the anchor head size. The anchorage behavior becomes ductile by increasing member thickness or by having surface reinforcement, whereas it becomes stiff and more brittle by increasing the size of anchor head. To account for the influence of member thickness, size of anchor head, and orthogonal surface reinforcement on the tensile breakout capacity of headed anchors, the CC method was modified and extended by incorporating three modification factors.
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| 8. |
- Nilforoush, Rasoul, et al.
(författare)
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Numerical Modelling and Experimental Verification of Pullout Loading of Anchor Bolts in Reinforced Concrete Structures
- 2016
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Ingår i: IABSE CONGRESS, STOCKHOLM, 2016. - CH - 8093 Zürich, Switzerland. - 9783857481444 ; , s. 2172-2178
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Konferensbidrag (refereegranskat)abstract
- The aim of this study is to provide a numerical model which can realistically present the failure load and failure mechanism of pullout loaded anchor bolts (headed studs) in reinforced concrete structures. The numerical analysis is carried out through a three-dimensional finite element (FE) code based on the Microplane constitutive law. The intension is to calibrate the FE model and to verify the numerical results against available test results. The calibrated FE model is intended to be used for an ongoing study to evaluate the influence of member thickness, surface reinforcement and size of anchor head on the tensile capacity and performance of anchor bolts.The simulation results showed very good agreements with the available test results. The objectivity of numerical modelling in respect to the size of finite elements as well as the defined boundary conditions was confirmed by additional numerical analyses.
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| 9. |
- Nilforoush, Rasoul, et al.
(författare)
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Tensile breakout capacity of cast-in-place headed anchors in concrete
- 2017
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Ingår i: XXIIIth Symposium on Nordic Concrete Research & Developement. - Oslo, Norway. - 9788282080569 ; , s. 235-238
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Konferensbidrag (refereegranskat)abstract
- The influence of member thickness, size of anchor head, and orthogonal surface reinforcement on the tensile breakout capacity of cast-in-place headed anchors was studied both numerically and experimentally. The aim of this paper is to form a background for developing improved methods for the design of new fastening systems as well as the assessment of the current anchorage systems in practice. Numerical and experimental results showed that the tensile breakout capacity of anchor bolts increases by increasing the member thickness or if surface reinforcement is present. Furthermore, the anchorage capacity increases with increasing the anchor head size.
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- Huang, Zheng, et al.
(författare)
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A practical method for predicting shear deformation of reinforced concrete beams
- 2020
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Ingår i: Engineering structures. - : Elsevier. - 0141-0296 .- 1873-7323. ; 206
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a practical method for predicting the deflections, including both the flexure and shear contributions, of reinforced concrete (RC) beams. The shear force - shear strain (V-γ) curve of a section in the shear span of RC beams is represented by a piecewise model and the tangent shear stiffness after shear cracking, Kt,cr, is assumed to be constant. A 2D finite element model, which has been validated for predicting shear deformation of RC beams, was used to identify factors that may affect the shear reduction factor (the ratio of Kt,cr to the elastic shear stiffness) and establish methodology for predicting the V-γ curve. Two types of methods, integration-form and closed-form, for predicting the total deflection were developed, in which the flexure-induced deflection (FD) was predicted using the Bischoff model while the shear-induced deflection (SD) was predicted using the method proposed in this paper. Comparison of the predictions with experimental results confirms that the Bischoff model provides reliable predictions of FDs of RC beams with and without shrinkage. It also shows that the proposed method can provide accurate predictions for SD after shear cracking, provided the effect of shrinkage on the shear cracking load is adequately quantified.Support from: National Natural Science Foundation of China (No. 51378104) and A Project Funded by the Priority Academic Program Development ofJiangsu Higher Education Institutions. The Development Fund of the Swedish Construction Industry (SBUF), the Swedish Research Council Formas and Elsa and Sven Thysell Foundation
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