Nonlinear Numerical Model of Post-Tensioned Elastic Rocking Panels for Application in Building Structural Analysis

2020 ◽  
Vol 146 (2) ◽  
pp. 04019202
Author(s):  
Thang N. Dao ◽  
Tu X. Ho
Keyword(s):  
Structural Analysis ◽  
Numerical Model ◽  
Nonlinear Numerical Model ◽  
Post Tensioned

Monotonic and fatigue assessment of steel-concrete composite beams strengthened with externally post-tensioned tendons

2018 ◽  
Author(s):  
◽  
Ayman Elzohairy
Keyword(s):  
Numerical Model ◽  
Composite Beam ◽  
Composite Beams ◽  
Fatigue Tests ◽  
Flexural Behavior ◽  
Bending Test ◽  
Steel Beam ◽  
Premature Failure ◽  
Post Tensioning ◽  
Post Tensioned

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The steel-concrete composite beam represents a structural system widely employed in both buildings and girder bridges. The coupling between steel beams and concrete flanges assures both economic and structural benefits because of quick construction of steel structures and large increase in stiffness due to the presence of concrete. Strengthening with external post-tensioning (PT) force is particularly effective and economical for long-span steel-concrete composite beams and has been employed with great success to increase the bending and shear resistance and correct excessive deflections. Applying external PT force to the steel-concrete composite beam is considered an active strengthening technique that can create permanent internal straining action in the beam which is opposite to the existing straining action due to the applied service loads. The most benefits of using this system of strengthening are an elastic performance to higher loads, higher ultimate capacity, and reduction in deformation under the applied loads. Under service loads, bridge superstructures are subjected to cyclic loads which may cause a premature failure due to fatigue. Therefore, fatigue testing is critical to evaluate existing design methods of steel-concrete composite beams. ... This research presents static and fatigue tests on four steel-concrete composite specimens to evaluate the effect of externally post-tensioned tendons on the ultimate strength and fatigue behavior of composite beams. Fatigue tests are conducted to a million cycles under a four-point bending test. In addition, final static tests are performed on fatigued specimens to evaluate the residual strength of the strengthened specimen. A numerical model is described to predict the fatigue response of the composite beam by considering the fatigue damage in the concrete flange. The accuracy of the developed numerical model is validated using the existing test data. The static test results indicate that the external post-tensioning force improves the flexural behavior of the strengthened specimen by increasing the beam capacity and reducing the tensile stress in the bottom flange of the steel beam. The fatigue results demonstrate that the external post-tensioning significantly decreases the strains in the shear connectors, concrete flange, and steel beam. The tendons demonstrated an excellent fatigue performance, with no indication of distress at the anchors.

A numerical model of the air flow above water waves. Part 2

1977 ◽  
Vol 82 (2) ◽  
pp. 349-369 ◽  
Author(s):  
P. R. Gent
Keyword(s):  
Energy Transfer ◽  
Numerical Model ◽  
Water Waves ◽  
Air Flow ◽  
Field Observations ◽  
Transfer Rates ◽  
Fractional Rate ◽  
Theoretical Predictions ◽  
The Waves ◽  
Nonlinear Numerical Model

Further results from the nonlinear numerical model of the air flow in a deep turbulent boundary layer above water waves described in Gent & Taylor (1976) are presented. The results are calculated with the surface roughness z0 both constant and varying with position along the wave. With the form used when z0 varies, the fractional rate |ζ| of energy transfer per radian advance in phase due to the working of the pressure forces is larger than for z0 constant both when the transfer is from wind to waves and when it is from waves to wind. The latter case occurs when the waves are travelling faster than, or against, the wind. The energy transfer rates are compared with other theoretical predictions and with recent field observations.

A Novel Application of the Thermal Probe: Nonlinear and Phase Change Problems

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
M. H. Adjali
Keyword(s):  
Thermal Conductivity ◽  
Parameter Estimation ◽  
Numerical Model ◽  
Phase Change ◽  
Estimation Technique ◽  
Thermal Probe ◽  
Temperature Dependent ◽  
Agar Gel ◽  
Nonlinear Numerical Model ◽  
Thermal Conductivities

This paper reports on a new application of the thermal probe in nonlinear systems. Whereas the thermal probe has been originally developed to determine the thermal conductivity in linear cases (where the thermophysical properties are considered independent of the temperature), the method used here exploits a direct nonlinear numerical model associated with a parameter estimation technique to determine temperature dependent thermal conductivities. It has been applied to a water-agar gel during phase change and the thermal conductivities within the corresponding temperature interval could be determined.

Parametric study for post-tensioned composite beams with external tendons

2017 ◽  
Vol 20 (10) ◽  
pp. 1433-1450 ◽  
Author(s):  
Ayman El-Zohairy ◽  
Hani Salim
Keyword(s):  
Numerical Model ◽  
Test Data ◽  
Fatigue Cracks ◽  
Composite Beams ◽  
Flexural Behavior ◽  
Nonlinear Simulation ◽  
Shear Connection ◽  
Strengthened Beam ◽  
Post Tensioning ◽  
Post Tensioned

Strengthening of bridge superstructures composite beams with external post-tensioned tendons is a good technique for strengthening the existing structures. In this study, a numerical model is illustrated to study the nonlinear simulation of composite beams stiffened with externally post-tensioned tendons. The accuracy of the developed numerical model is validated using comparisons between the numerical and existing test data. The influence of various strengthening parameters is investigated, which include draped versus straight tendons, tendon length, the effect of post-tensioning on reinstating the flexural behavior of an overloaded beam, tendon eccentricity, and the degree of shear connection. A good agreement between the proposed model and the test data is obtained. The results demonstrate that at the same tendon eccentricity, the trapezoidal profile shows better behavior for the strengthened beams. However, more ductility is obtained when using the straight tendon profile. Applying post-tensioning through the beam of full length helps to reduce the creation of fatigue cracks, which always start at stress raisers, and subsequently increases the fatigue life of the composite beam. Also, the external post-tensioning effectively maintains the flexural behavior of the overloaded strengthened beam after unloading in comparison to the un-strengthened beam. It is observed that 80% degree of shear connection or higher is recommended to obtain the desired performance of the external post-tensioning force for strengthening composite beams.

Evaluation of Piled Raft Performance Using a Verified 3D Nonlinear Numerical Model

2017 ◽  
Vol 35 (4) ◽  
pp. 1831-1845 ◽  
Author(s):  
Ahmed M. Alnuaim ◽  
Hany El Naggar ◽  
M. Hesham El Naggar
Keyword(s):  
Numerical Model ◽  
Piled Raft ◽  
Nonlinear Numerical Model
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