Effect of Taper on Shear Stiffness of Steel-Reinforced Neoprene Bearing Pads

2021 ◽  
pp. 036119812199670
Author(s):  
Satyajeet R. Patil ◽  
Gary R. Consolazio ◽  
H. R. Hamilton
Keyword(s):  
Axial Load ◽  
Experimental Testing ◽  
Shear Stiffness ◽  
Load Level ◽  
Construction Time ◽  
Plan View ◽  
Temperature Changes ◽  
Elastomeric Bearing ◽  
Live Loads ◽  
Bridge Bearing

Steel-reinforced elastomeric bearing pads are widely used in bridge construction to vertically support girders on piers while also accommodating translational and rotational girder deformations caused by live loads and temperature changes. To support sloped girders, flat bearing pads of uniform thicknesses are typically used with either tapered steel shim plates or an inclined concrete bearing seat. The use of tapered pads has the potential to reduce both construction time and cost by eliminating the need for tapered plates or seats to match the girder slope. However, limited research has been performed to investigate the effect of introducing taper on relevant design properties of bearing pads. In this paper, results are presented from experimental testing that was performed to quantify the effect of taper on shear stiffnesses of pads having varied geometric characteristics (plan view dimensions, elastomer thicknesses, and slope angles). An experimental bearing pad test device was designed and utilized to impose shear loads in accordance with ASTM standards, while simultaneously maintaining a constant axial load. Bearing pads chosen for testing were tapered variations of standard flat bridge bearing pads used in the state of Florida, U.S. Results obtained from the study revealed that shear stiffness was not significantly influenced by the introduction of taper angle, the direction of shear along the length of pads, or axial load level. The shear stiffness of tapered pads remained within approximately 10% of the shear stiffness of corresponding flat pads.

scholarly journals The seismic performance of steel encased reinforced concrete bridge piles

1983 ◽  
Vol 16 (2) ◽  
pp. 123-140
Author(s):  
R. J. T. Park ◽  
M. J. N. Priestley ◽  
W. R. Walpole
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Theoretical Investigation ◽  
Axial Load ◽  
Lateral Displacement ◽  
Load Level ◽  
Concrete Bridge ◽  
Reinforced Concrete Bridge ◽  
Outside Diameter ◽  
Good Agreement

An experimental and theoretical investigation into the seismic performance of steel encased reinforced concrete bridge piles is described. Six test units were designed, constructed and tested
under cyclic lateral displacement-controlled loading. The units had
an outside diameter of 360 mm and a steel casing thickness of 5 mm. Variables included the axial load level, inclusion or exclusion of internal reinforcing cages, and the influence of the casing continuity at he critical flexural sections. Sound seismic performance was observed in all of the models and good agreement between predicted and observed ultimate behaviour was obtained.

scholarly journals The Proposition of an EI Equation of Square and L–Shaped Slender Reinforced Concrete Columns under Combined Loading

2021 ◽  
Vol 11 (3) ◽  
pp. 7100-7106
Author(s):  
L. Hamzaoui ◽  
T. Bouzid
Keyword(s):  
Reinforced Concrete ◽  
Axial Load ◽  
Concrete Strength ◽  
Linear Regression Analysis ◽  
Strain Curve ◽  
Load Level ◽  
Combined Loading ◽  
Actual Behavior ◽  
Factors Affecting ◽  
Slender Columns

The stability and strength of slender Reinforced Concrete (RC) columns depend directly on the flexural stiffness EI, which is a major parameter in strain calculations including those with bending and axial load. Due to the non-linearity of the stress-strain curve of concrete, the effective bending stiffness EI always remains variable. Numerical simulations were performed for square and L-shaped reinforced concrete sections of slender columns subjected to an eccentric axial force to estimate the variation of El resulting from the actual behavior of the column, based on the moment-curvature relationship. Seventy thousand (70000) hypothetical slender columns, each with a different combination of variables, were used to investigate the main variables that affect the EI of RC slender columns. Using linear regression analysis, a new simple and linear expression of EI was developed. Slenderness, axial load level, and concrete strength have been identified as the most important factors affecting effective stiffness. Finally, the comparison between the results of the new equation and the methods proposed by ACI-318 and Euro Code-2 was carried out in connection with the experimental results of the literature. A good agreement of the results was found.

SEISMIC PERFORMANCE OF GFRP-RC RECTANGULAR COLUMNS: NUMERICAL STUDY

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ehab El-Salakawy ◽  
Fangxin Ye ◽  
Yasser Mostafa Selmy
Keyword(s):  
Reinforced Concrete ◽  
Cyclic Loading ◽  
Axial Load ◽  
Numerical Study ◽  
Concrete Strength ◽  
Weight Ratio ◽  
Concrete Columns ◽  
Load Level ◽  
Reinforced Concrete Columns ◽  
Rectangular Columns

Composite materials like glass fiber-reinforced polymer (GFRP) is becoming widely acceptable to be used as a reinforcing material due to its high ultimate tensile strength-to-weight ratio and excellent resistance to corrosion. However, the seismic behavior of GFRP-reinforced concrete columns has not been fully investigated yet. This paper presents the results of a numerical analysis of full-size GFRP-RC rectangular columns under cyclic loading. The simulated column depicts the lower part of a building column between the foundation and the point of contra-flexure at the mid-height of the column. GFRP reinforcement properties and concrete modeling based on fracture energy have been incorporated in the numerical model. Experimental validation has been used to examine the accuracy of the constructed finite element models (FEMs) using a commercially available software. The validated FEM was used to perform a parametric study, considering several concrete strength values and axial load levels, to study its influence on the performance of the GFRP-reinforced concrete columns under cyclic loading. It was concluded that the hysteretic dissipation capacity deteriorates under high axial load level due to severe softening of the concrete. The FE results showed a substantial improvement of the lateral load-carrying capacities by increasing concrete compressive strength.

EFFECT OF ASPECT RATIO ON THE BEHAVIOR OF GFRP-RC CIRCULAR COLUMNS UNDER SIMULATED SEISMIC LOADING

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Amr Elsayed Mohammed Abdallah ◽  
Ehab Fathy El-Salakawy
Keyword(s):  
Aspect Ratio ◽  
Axial Load ◽  
Load Capacity ◽  
Load Level ◽  
Experimental Results ◽  
Rc Columns ◽  
Drift Capacity ◽  
Glass Fiber Reinforced ◽  
Axial Load Capacity ◽  
Code Provisions

The mechanical and physical properties of glass fiber-reinforced polymer (GFRP) reinforcement are different from steel, which requires independent code provisions for GFRP-reinforced concrete (RC) members. The currently available code provisions for GFRP-RC members still need more research evidence to be inclusive. For example, the available provisions for confinement reinforcement of FRP-RC columns do not consider the effects of column aspect ratio, which is not yet supported by any available research data. In this study, two full-scale spirally reinforced GFRP-RC circular columns were constructed and tested under concurrent seismic and axial loads. Both specimens had an aspect ratio (shear span-to-diameter ratio) of 7.0, while other two specimens with an aspect ratio of 5.0, from a previous stage of this study, were included for comparison purposes. For each aspect ratio, each specimen was loaded under one of two levels of axial load; 20 or 30% of the axial load capacity of the column section. All test specimens had a 35 MPa concrete compressive strength, 350-mm diameter, 85-mm spiral pitch and 1.2% longitudinal reinforcement ratio. The experimental results were analyzed in terms of hysteretic response, drift capacity and inelastic deformability hinge length. Based on the experimental results, it can be concluded that the aspect ratio affects the magnitude of secondary moments and inelastic deformability hinge length. In addition, the aspect ratio may affect drift capacity of GFRP-RC columns, depending on axial load level.

scholarly journals Gravity Load Collapse Behavior of Nonengineered Reinforced Concrete Columns

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Chichaya Boonmee ◽  
Kittipoom Rodsin ◽  
Krissachai Sriboonma
Keyword(s):  
Reinforced Concrete ◽  
Cyclic Loading ◽  
Axial Load ◽  
Concrete Columns ◽  
Poor Quality ◽  
Load Level ◽  
Longitudinal Reinforcement ◽  
Reinforced Concrete Columns ◽  
Gravity Load ◽  
Collapse Behavior

This paper aims at investigating gravity load collapse behavior of extremely poor quality reinforced concrete columns under cyclic loading. Such columns were usually constructed by local people and may not be designed to meet any of the standards. It was found that their concrete strength may be as low as 5 MPa and the amount of longitudinal reinforcement may be lower than 1%. This type of column is deliberately defined as “nonengineered reinforced concrete column,” or NRCC. During earthquake, the gravity load collapse of the NRCC columns caused a large number of death tolls around the world. In this study, four columns as representative of existing NRCC were tested under cyclic loading. The compressive strength of concrete in order of 5 MPa was used to be representative of columns with poor quality concrete. Two axial load levels of 6 and 18 tons were used to study the influence of axial load level on maximum drift at gravity load collapse. To investigate the effect of bar types on drift capacity, 9 mm round bars were used in two specimens and 12 mm deformed bars were used for the rest of the specimens. The maximum drift before gravity load collapse was very dependent on the axial load level. The maximum drift of the specimens subjected to high axial load (18 tons) was extremely low at approximately 1.75% drifts. The use of deformed bars (associated with larger amount of longitudinal reinforcement) caused the damage to severely dissipate all over the height of the columns. Such damage caused columns to collapse at a lower drift compared to those using round bars. Finally, the plastic hinge model was used to predict the maximum drift of the low strength columns. It was found that the model overly underestimates the drift at gravity load collapse.

scholarly journals Investigation of Parameters Affecting the Equivalent Yield Curvature of Reinforced Concrete Columns

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1594
Author(s):  
Umut Hasgul
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Axial Load ◽  
Concrete Columns ◽  
Load Level ◽  
Combined Effects ◽  
Reinforced Concrete Columns ◽  
Independent Effects ◽  
Equivalent Yield ◽  
Section Dimension

In this study, the response quantities affecting the equivalent yield curvature, which is important in the deformation-based seismic design and assessment of structural systems, are investigated for reinforced concrete columns with a square cross-section. In this context, the equivalent yield curvatures were determined by conducting moment–curvature analyses on various column models, in which the axial load level, cross-section dimension, longitudinal reinforcement ratio, and concrete compression strength were changed parametrically, and the independent and/or combined effects of the relevant parameters were discussed. Depending on the axial load levels of P/Agfc′ < 0.3, P/Agfc′ = 0.3, and P/Agfc′ > 0.3 for the considered columns, the yielding of reinforcement, yielding of reinforcement and/or concrete crushing, and concrete crushing governed the yield conditions, respectively. It can be noted that the cross-section dimension and axial load level became the primary parameters. Even though the independent effects with regard to particular parameters remained at minimal levels, the combined effects of them with the axial load became important in terms of the equivalent yield curvature.

Finite Element Analysis of Concrete-Filled Rectangular Tubular Frame

2014 ◽  
Vol 578-579 ◽  
pp. 695-698
Author(s):  
Xi Le Li ◽  
Li Hua Niu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Axial Load ◽  
Seismic Behavior ◽  
Element Model ◽  
Load Level ◽  
Hysteresis Curve ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Nonlinear Finite Element Model

Based on the model experiment on seismic behavior of a 1-span, 2-story concrete-filled rectangular steel tubal (CFRST) frame under lateral cyclic loads, a 3-D nonlinear finite element model of concrete-filled rectangular steel tubular frame is proposed in the paper. Compared with the experimental hysteresis curve, the computational results are found to be accurate, which shows that this model proposed in the paper can be applied in structure analysis of concrete-filled rectangular tubular frames. So the model was used in the finite element analysis of concrete-filled rectangular frame with different axial load level. Compared the computational displacement envelop curves, it concludes that the ductility and bearing capacity of CFRST frames reduces with the increasing axial load level.

Actuator Applications with Single-Crystals of Cu-Zn-Al Shape Memory Alloy

1996 ◽  
Vol 459 ◽  
Author(s):  
A. A. Yawny ◽  
M. Sade ◽  
F. C. Lovey
Keyword(s):  
Single Crystal ◽  
Shape Memory ◽  
Single Crystals ◽  
Load Level ◽  
Cycle Number ◽  
Temperature Changes ◽  
Friction Temperature ◽  
Response To Temperature ◽  
Thermostatic Device ◽  
Experimental Stage

ABSTRACTIn the present work the use of single-crystals of Cu-Zn-Al Shape Memory Alloys (SMA) in actuator applications is analyzed. The actuator considered here, a device capable of doing work in response to temperature changes, is based on a single-crystal nucleus of a Cu-Zn-Al SMA coupled to a conventional spring that represents the load to be displaced. A special experimental stage was designed for performing controlled thermal cycles under load. In this way the effects of different parameters (cycle number, friction, temperature range, load level) on the actuator behavior can be studied. From the results obtained, the use of a single-crystal of an SMA in a thermostatic device is analyzed and compared with the commercial wax actuator performance.

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