Utilization of partial end restraint in bridge strengthening

1994 ◽  
Vol 21 (5) ◽  
pp. 836-846
Author(s):  
F. Wayne Klaiber ◽  
Terry J. Wipf ◽  
Rula B. Abu-Kishk
Keyword(s):  
Composite Structures ◽  
Analytical Investigation ◽  
Experimental Results ◽  
Analytical Models ◽  
Finite Element Analyses ◽  
Test Beam ◽  
Bridge Model ◽  
Bridge Strengthening ◽  
End Restraint ◽  
Concrete Deck

The purpose of this investigation is to determine a technique for increasing the capacity of bridges to accommodate today's increase in loading. Strengthening existing steel stringers in composite, steel-beam, concrete-deck bridges by providing partial end restraint is shown to be feasible. The research program included a review of existing literature, testing of a full-scale bridge beam and a 1/3-scale bridge model, and finite-element analyses of the restraint brackets, the test beam, and the model bridge. Analytical and experimental results of this investigation are presented, as well as results from an analytical investigation of the bridge model when subjected to various degrees of end restraint. Six different degrees of end restraint were examined. The achieved percent reductions ranged from 12% to 26% for midspan strains, 20% to 30% for midspan deflections, and 10% to 32% for beam end rotations. The correlation between the analytical and experimental results verified the basic design assumptions; thus, the analytical models can be used for determining the location and the degree of end restraint required to strengthen an existing bridge. Key words: bridges, girder, composite structures, tests, models, strengthening, rehabilitation, restraint.

A Damage Analysis of Steel-Concrete Composite Beams Via Dynamic Methods: Part II. Analytical Models and Damage Detection

2003 ◽  
Vol 9 (5) ◽  
pp. 529-565 ◽  
Author(s):  
Michele Dilena ◽  
Antonino Morassi
Keyword(s):  
Damage Detection ◽  
Dynamic Behavior ◽  
Concrete Slab ◽  
Composite Beams ◽  
Analytical Investigation ◽  
Experimental Results ◽  
Analytical Models ◽  
Reinforced Concrete Slab ◽  
Dynamic Methods ◽  
Positive Results

This paper is the second part of an experimental-analytical investigation on the dynamic behavior of damaged steel-concrete composite beams. In the first part of the research, we presented and discussed the experimental results of a comprehensive series of dynamic tests performed on composite beams with damage in the connection. Experimental observations suggested the formulation of a composite beam analytical model, where the strain energy density of the connection also includes an energy term associated to the occurrence of relative transversal displacements between the reinforced concrete slab and the steel beam. A comparison with experimental results shows that the model enhances accuracy in describing the undamaged state of composite beams and that it is also appropriate to accurately predict the dynamic behavior under damaged conditions. A damage detection technique based on the measurement of variation in the first flexural frequencies was then applied to the suggested model and gave positive results.

scholarly journals Comparison of Analytical Approaches Predicting the Compressive Strength of Fibre Reinforced Polymers

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2517 ◽  
Author(s):  
Christian Leopold ◽  
Sergej Harder ◽  
Timo Philipkowski ◽  
Wilfried Liebig ◽  
Bodo Fiedler
Keyword(s):  
Compressive Strength ◽  
Prediction Accuracy ◽  
Volume Fraction ◽  
Fibre Volume Fraction ◽  
Experimental Results ◽  
Analytical Models ◽  
Reinforced Polymers ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Analytical Approaches

Common analytical models to predict the unidirectional compressive strength of fibre reinforced polymers are analysed in terms of their accuracy. Several tests were performed to determine parameters for the models and the compressive strength of carbon fibre reinforced polymer (CFRP) and glass fibre reinforced polymer (GFRP). The analytical models are validated for composites with glass and carbon fibres by using the same epoxy matrix system in order to examine whether different fibre types are taken into account. The variation in fibre diameter is smaller for CFRP. The experimental results show that CFRP has about 50% higher compressive strength than GFRP. The models exhibit significantly different results. In general, the analytical models are more precise for CFRP. Only one fibre kinking model’s prediction is in good agreement with the experimental results. This is in contrast to previous findings, where a combined modes model achieves the best prediction accuracy. However, in the original form, the combined modes model is not able to predict the compressive strength for GFRP and was adapted to address this issue. The fibre volume fraction is found to determine the dominating failure mechanisms under compression and thus has a high influence on the prediction accuracy of the various models.

Influence of backing materials towards the fatigue strength of butt-welded joints

2011 ◽  
Vol 225 (8) ◽  
pp. 1798-1807 ◽  
Author(s):  
M H Kim ◽  
H J Kim ◽  
J H Han ◽  
J M Lee ◽  
Y D Kim ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Strength ◽  
Welded Joints ◽  
Fatigue Tests ◽  
Experimental Results ◽  
Finite Element Analyses ◽  
Cold Metal Transfer ◽  
Notch Stress ◽  
Effective Notch Stress ◽  
Cold Metal

The purpose of this study is to investigate the fatigue strength of butt-welded joints with special attention paid to employing different kinds of backing plates. The effect of the under-matched weld was also considered. Four different cases of backing scenarios for butt-welded specimens such as steel backing, ceramic backing, CMT (no backing by cold metal transfer) and UM (under-matched welded specimen) were investigated. A series of fatigue tests was performed to compare the fatigue strength of butt-welded joints with respect to different backing scenarios. Effective notch stress was used for the interpretation of fatigue strength of butt-welded specimens with backing plates based on finite element analyses for calculating fatigue notch factors. When results were presented from the effective notch stress, all backing scenarios considered in this study exhibited the fatigue strengths corresponding to the FAT 225 curve. From the experimental results of this study, it was determined that the fatigue strengths of butt-welded joints were found to be in the order of CMT, ceramic backing, UM, and steel backing. No significant decrease in fatigue strength, however, was observed when backing plates were steel backing and ceramic backing types.

scholarly journals Flexural Behavior of Fiber-Reinforced Self-Stressing Concrete T-Shaped Composite Beams

2020 ◽  
Vol 2020 ◽  
pp. 1-17 ◽  
Author(s):  
Boxin Wang ◽  
Ruichang Fang ◽  
Qing Wang
Keyword(s):  
Composite Beam ◽  
Mechanical Analysis ◽  
Composite Beams ◽  
Experimental Results ◽  
Flexural Behavior ◽  
Fiber Reinforced ◽  
Beam Test ◽  
Test Beam ◽  
Bending Performance ◽  
Laminated Layer

Given the excellent crack resistance performance of steel fiber-reinforced self-stressing concrete (SFRSSC), the bending performance of some composite beams with SFRSSC laminated layers was studied. The experiment conducted in this study comprised a single-span composite beam test (including 3 test beams) and a two-span continuous composite beam test (including 2 test beams). All the test beams were T-shaped. The cracking load, yielding load, and ultimate load of all the test beams were recorded and comparatively analyzed. Experimental results showed that the cracking load of the test beam with an SFRSSC laminated layer is significantly increased. Mechanical analysis and numerical simulation of the test beams were conducted, and the obtained results agreed well with the experimental results. The composite beams under different working conditions were also numerically simulated. Through the simulation, reasonable ranges of precompressive stress and length of the SFRSSC laminated layer at intermediate support of continuous composite beam were obtained.

Damage detection of unidirectional carbon fiber–reinforced laminates with embedded magnetostrictive particulates: A preliminary study

2012 ◽  
Vol 24 (8) ◽  
pp. 991-1006 ◽  
Author(s):  
Oliver J Myers ◽  
George Currie ◽  
Jonathan Rudd ◽  
Dustin Spayde ◽  
Nydeia Wright Bolden
Keyword(s):  
Composite Materials ◽  
Carbon Fiber ◽  
Nondestructive Evaluation ◽  
Composite Laminates ◽  
Composite Structures ◽  
Single Layer ◽  
Polymeric Composite ◽  
Analytical Models ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced

Defects in composite laminates are difficult to detect because of the conductive and paramagnetic properties of composite materials. Timely detection of defects in composite laminates can improve reliability. This research illustrates the preliminary analysis and detection of delaminations in carbon fiber laminate beams using a single layer of magnetostrictive particles and noncontacting concentric magnetic excitation and sensing coils. The baseline analytical models also begin to address the intrusive nature of the magnetostrictive particles as well as relate the applied excitation field with the stress and magnetic flux densities induced in the magnetostrictive layer. Numerical methods are used to begin to characterize the presence of magnetostrictive particles in the laminate and the behavior of the magnetostrictive particles in relationship to the magnetic field used during sensing. Unidirectional laminates with embedded delaminations are used for simulations and experimentations. A novel, yet simplified fabrication method is discussed to ensure consistent scanning and sensing capabilities. The nondestructive evaluation scanning experiments were conducted with various shapes and sizes of damages introduced into carbon fiber–reinforced polymeric composite structures. The results demonstrate high potential for magnetostrictive particles as a low-cost, noncontacting, and reliable sensor for nondestructive evaluation of composite materials.

Analytical Model for the Deformation of Viscoelastic Non-Newtonian Drops Undergoing Secondary Atomization

2016 ◽  
Author(s):  
Sharon E. Snyder ◽  
Varun Kulkarni ◽  
Paul E. Sojka
Keyword(s):  
Analytical Model ◽  
Xanthan Gum ◽  
Experimental Results ◽  
Analytical Models ◽  
Drop Diameter ◽  
Droplet Deformation ◽  
Secondary Atomization ◽  
Starting Point ◽  
Breakup Model ◽  
Xanthan Gum Solution

While there is no single analytical model that accurately predicts all stages and modes of secondary atomization, many groups have developed models that predict deformation and oscillation of a single, isolated drop. The TAB (Taylor Analogy Breakup) model was chosen for this investigation, mainly due to its widespread use by Liu and Reitz [1], Hwang et al. [2], Tanner [3], and Lee and Reitz [4], among others. Since the TAB model is also the foundation for many other analytical models, it will also be used here as a starting point for the development of a viscoelastic non-Newtonian model to predict droplet deformed radii, droplet deformation time, and velocity at deformation time for viscoelastic xanthan gum - DI water solutions. Three additional improvements are made to this viscoelastic TAB model: the first is a change to a TAB coefficient; the second to the equation for the drag coefficient, and the third modification is to the breakup criterion. This model uses Carreau rheology and Zimm relaxation time. Non-dimensional drop diameter and initiation times are plotted against We; model results are compared to experimental results for a range of xanthan gum solution concentrations. Results show fair agreement between experimental results and model results for non-dimensional drop diameter, with the best match at low XG concentration and low-to-medium We (10–30). It was also noted that increased viscoelasticity seems to increase this drop diameter. Good agreement between experimental data and model results has been seen for initiation time, with increased viscoelasticity increasing this parameter as well.

Experimental and Analytical Investigation on Spaghetti Problem

2001 ◽  
Author(s):  
Yoshimasa Komaki ◽  
Nobuyuki Kobayashi ◽  
Masahiro Watanabe
Keyword(s):  
Dynamic Behavior ◽  
Multibody Dynamics ◽  
Constant Velocity ◽  
Analytical Investigation ◽  
Experimental Results ◽  
Flexible Beam ◽  
Gap Size ◽  
Lateral Vibration ◽  
Elastic Wall ◽  
Pulling Velocity

Abstract The dynamic behavior of the flexible beam, which is pulled into the slit of the elastic wall with a constant velocity, is discussed with multibody dynamics formulation and experiments. The vibration of the free tip of a flexible beam increases rapidly as pulling into the slit, and this behavior is called “Spaghetti Problem”. The effect of gap size of the slit on the behavior of Spaghetti Problem is especially focused. Dynamic behavior of the beam is simulated numerically and examined the accuracy of the presented formulation by changing the gap size and the pulling velocity of the beam as parameters. It is clarified that the presented modeling method simulates the experimental results quite well, and the gap size and the pulling velocity influence the increase of the lateral vibration near the inlet of the slit.

Linear Two-Port Model of an Active Thermoplastic Composite Structure

2013 ◽  
Author(s):  
Anja Winkler ◽  
Uwe Marschner ◽  
Eric Starke ◽  
Niels Modler ◽  
Wolf-Joachim Fischer ◽  
...  
Keyword(s):  
Composite Structure ◽  
Manufacturing Process ◽  
Composite Structures ◽  
Matrix Material ◽  
Manufacturing Technology ◽  
Experimental Results ◽  
Thermoplastic Composite ◽  
Starting Point ◽  
Modal Behavior ◽  
Active Composite

This paper describes new active composite structures based on thermoplastic matrices which contain material homogeneous embedded piezoceramic modules. Starting point is the development of novel thermoplastic compatible piezoceramic modules, so called TPMs. By the utilization of the same matrix material for the composite structure and for the TPM carrier films, these modules afford an opportunity to become directly embedded into the component during its manufacturing process. In this context, the manufacturing technology of the TPMs and of the active composite structure is presented. Furthermore, selected test samples are investigated concerning their modal behavior. Based on the determined characteristics a linear two-port model is used for the reproduction of the experimental results.

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