scholarly journals MECHANICAL BEHAVIOR OF HORIZONTAL SWIVEL SYSTEM WITH UHPC SPHERICAL HINGE UNDER SEISMIC ACTION

2021 ◽  
Vol 30 (2) ◽  
Author(s):  
Jiawei Wang ◽  
Bing Cao ◽  
Bo Huang ◽  
Yihan Du
Keyword(s):  
Optimization Algorithm ◽  
Seismic Waves ◽  
Response Spectrum ◽  
Time History ◽  
Bending Moment ◽  
Simulation Models ◽  
Superposition Method ◽  
Seismic Action ◽  
Mode Superposition Method ◽  
Spherical Hinge

In the process of rotation, the total weight of the bridge structure is jointly supported by the spherical hinge and the supporting structure, and its lateral stability is poor. It is easy to lose stability under the action of dynamic loads such as seismic action effect. The present paper takes a 10,000-ton continuous rigid frame swivel bridge as the re-search object, analyzes the dynamic response of the seismic action to the horizontal swivel system, and establishes several structure simulation models. Eighteen seismic waves in three directions that meet the calculation requirements are screened for time history analysis and compared with the response spectrum method. Finally, an optimization algorithm for the seismic response of the bridge under horizontal swivel system is proposed based on the mode superposition method. The UHPC spherical hinge bears all the vertical forces and 20% of the bending moment caused by the seismic action, the support structure bearing the remaining 80% of the bending moment. The optimization algorithm proposed in this paper features high accuracy.

Seven Mega Floor MSCSS Modal Analysis

2013 ◽  
Vol 353-356 ◽  
pp. 2210-2215
Author(s):  
Jun Jun Wang ◽  
Lu Lu Yi
Keyword(s):  
Modal Analysis ◽  
Response Spectrum ◽  
Time History ◽  
Response Analysis ◽  
Superposition Method ◽  
Response Spectrum Analysis ◽  
Mode Superposition Method ◽  
History Analysis ◽  
Basic Performance ◽  
Dynamic Time

Modal analysis is also known as dynamic analysis for mode-superposition method. In the seismic response analysis of linear structural systems, it is one of the most commonly used and the most effective ways. Through the modal analysis of building structure, we can get some basic performance parameters of the structure. These parameters can help us make qualitative judgments for the respond of a structure first, and can help us judge whether they meet demands for conceptual design. Modal analysis is also the basis of other dynamic response analysis, including dynamic time history analysis and response spectrum analysis.

Seismic response analysis of steel–concrete hybrid wind turbine tower

2021 ◽  
pp. 107754632110075
Author(s):  
Junling Chen ◽  
Jinwei Li ◽  
Dawei Wang ◽  
Youquan Feng
Keyword(s):  
Wind Turbine ◽  
Response Spectrum ◽  
Ground Motions ◽  
Time History ◽  
Seismic Action ◽  
Response Spectrum Method ◽  
Spectrum Method ◽  
Wind Turbine Tower ◽  
Ground Types ◽  
Nonlinear Time History

The steel–concrete hybrid wind turbine tower is characterized by the concrete tubular segment at the lower part and the traditional steel tubular segment at the upper part. Because of the great change of mass and stiffness along the height of the tower at the connection of steel segment and concrete segment, its dynamic responses under seismic ground motions are significantly different from those of the traditional steel tubular wind turbine tower. Two detailed finite element models of a full steel tubular tower and a steel–concrete hybrid tower for 2.0 MW wind turbine built in the same wind farm are, respectively, developed by using the finite element software ABAQUS. The response spectrum method is applied to analyze the seismic action effects of these two towers under three different ground types. Three groups of ground motions corresponding to three ground types are used to analyze the dynamic response of the steel–concrete hybrid tower by the nonlinear time history method. The numerical results show that the seismic action effect by the response spectrum method is lower than those by the nonlinear time history method. And then it can be concluded that the response spectrum method is not suitable for calculating the seismic action effects of the steel–concrete hybrid tower directly and the time history analyses should be a necessary supplement for its seismic design. The first three modes have obvious contributions on the dynamic response of the steel–concrete hybrid tower.

scholarly journals Transient Response of Bridge Piers to Structure Separation under Near-Fault Vertical Earthquake

2021 ◽  
Vol 11 (9) ◽  
pp. 4068
Author(s):  
Wenjun An ◽  
Guquan Song
Keyword(s):  
Large Scale ◽  
Bending Moment ◽  
Relative Displacement ◽  
Superposition Method ◽  
Longitudinal Displacement ◽  
Transient Wave ◽  
Vibration Period ◽  
Vertical Excitation ◽  
Mode Superposition Method ◽  
Main Girder

Given the possible separation problem caused by the double-span continuous beam bridge under the action of the vertical earthquake, considering the wave effect, the transient wave characteristic function method and the indirect mode superposition method are used to solve the response theory of the bridge structure during the earthquake. Through the example analysis, the pier bending moment changes under different vertical excitation periods and excitation amplitudes are calculated. Calculations prove that: (1) When the seismic excitation period is close to the vertical natural vibration period of the bridge, the main girder and the bridge pier may be separated; (2) When the pier has a high height, the separation has a more significant impact on the longitudinal displacement of the bridge, but the maximum relative displacement caused by the separation is random; (3) Large-scale vertical excitation will increase the number of partitions of the structure, and at the same time increase the vertical collision force between the main girder and the pier, but the effect on the longitudinal displacement of the form is uncertain; (4) When V/H exceeds a specific value, the pier will not only be damaged by bending, but will also be damaged by axial compression.

Post-Yielding Behavior of Hinge-Supported Wall with Buckling-Restrained Braces in Base

2019 ◽  
Vol 13 (03n04) ◽  
pp. 1940003 ◽  
Author(s):  
Xiaoyan Yang ◽  
Jing Wu ◽  
Jian Zhang ◽  
Yulong Feng
Keyword(s):  
Response Spectrum ◽  
Time History ◽  
Shear Wall ◽  
Seismic Intensity ◽  
Nonlinear Time History Analysis ◽  
Wall Structure ◽  
Superposition Method ◽  
Structural Wall ◽  
Design Response Spectrum ◽  
Buckling Restrained Braces

A novel structural wall with hinge support and buckling restrained braces (BRBs) set in the base (HWBB) is studied. HWBB can be applied to precast manufacturing due to its considerable ductility and the separate loading mechanism in HWBB–frame structure. In elastic stage, BRBs play a brace role to make the hinged wall resist horizontal forces like a shear wall. BRBs dissipate seismic energy through plastic and hysteresis effects after yielding and the damage is only concentrated in BRBs. The performance of an HWBB is equivalent to a shear wall structure with excellent ductility and stable energy dissipation capacity. Numerical analysis indicates that the hinged wall body in the HWBB well controls the deformation mode of the structure, avoiding the concentration of story drifts, thereby protecting the remaining parts of the structure. It is revealed that the moments of the wall body will generate significant increments after BRBs yielding, and the Seismic Intensity Superposition Method is proposed to calculate the moments. In this method, nonlinear response of an HWBB can be regarded as the sum of the responses of two elastic corresponding structures excited with two parts of the seismic intensity, respectively. Modes and moments equations of the hinged wall with uniform distribution of stiffness and mass are derived, and calculation results coincide with that of the nonlinear time history analysis (NHA). For a more general case, the white noise scan method is proposed to solve the structure’s natural characteristics and to further calculate the response. Finally, the post-yielding moment calculation method and the process based on design response spectrum are proposed. It is proved that the moments from proposed Seismic Intensity Superposition Method can envelop most of the moments from NHA, and it is a good estimate of the response of HWBB in nonlinear stage.

scholarly journals A simple method for determining seismic demands on gravity load frames

2017 ◽  
Vol 44 (8) ◽  
pp. 661-673 ◽  
Author(s):  
J. Beauchamp ◽  
P. Paultre ◽  
P. Léger
Keyword(s):  
Response Spectrum ◽  
Time History ◽  
Bending Moment ◽  
New Method ◽  
Simple Method ◽  
Seismic Demands ◽  
Gravity Load ◽  
Comparison Results ◽  
Seismic Force ◽  
Nonlinear Time History

This paper presents a simple method based on modal response spectrum analysis to compute internal forces in structural elements belonging to gravity framing not part of the seismic force resisting system (SFRS). It is required that demands on these gravity load resisting system (GLRS) be determined according to the design displacement profile of the SFRS. The proposed new method uses the fact that if the linear stiffness properties of the GLRS not part of the SFRS have negligible values compared to those of the SFRS, only the latter will provide lateral resistance. Displacements of the GLRS then correspond to those of the SFRS alone. The new method is illustrated by computing the seismic responses of a symmetric and an asymmetric multi-storey reinforced concrete building. These results are compared to those obtained from the application of the simplified analysis method proposed in the Canadian standard for the design of concrete structures. Nonlinear time history analyses are also performed to provide a benchmark for comparison. Results show that the new method can predict shear and bending moment in all members at once with ease. Therefore, this new simplified method can effectively be used to predict seismic forces in elements not considered part of the SFRS.

Characteristic Analysis of 3.11 Seismic Waves

2013 ◽  
Vol 838-841 ◽  
pp. 1484-1491
Author(s):  
Guo Ping Chen ◽  
Xiang Liang Ning ◽  
Hong Feng Guo ◽  
Han Yu Zhou
Keyword(s):  
Seismic Waves ◽  
Response Spectrum ◽  
Time History ◽  
Predominant Frequency ◽  
Characteristic Analysis ◽  
History Analysis ◽  
Spectral Components ◽  
Spectrum Distribution ◽  
Spectrum Characteristics ◽  
Basic Characteristics

33 records of Japanese earthquake are extracted in this paper (referred to as 3.11 seismic waves in the article).Then, through studying the basic characteristics, spectrum characteristics and anisotropic of 3.11 seismic waves, as well as the similarities and differences of the response spectrum of 3.11 seismic waves contrasting with the response spectrum of the code. The results show that: a) 3.11 seismic waves have rich spectral components almost near the predominant frequency and its energy mainly concentrate in 0.1~10Hz.b) By analyzing the spectrum distribution of the seismic waves, its destruction strength on different structures can be evaluated. c) Damaging strength of horizontal seismic waves is much larger than the vertical seismic waves. Serious damage to the structure can be caused by the horizontal seismic waves’ excellence spectrum components focusing on the frequency of the structure in the engineering. Vertical seismic waves have greater damage to the structures’ periods between 0.02s to 1s, but much smaller to other structures. d) it can effectively assess the damaging strength on the structure,in time history analysis ,when make 3.11 seismic waves as the input earthquake waves.

scholarly journals A Centrifuge Model Test of the Ground Motion Response in a Moderately Stiff Soil

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Jing-Yan Lan ◽  
Ting Wang ◽  
Diwakar Khatri Chhetri ◽  
Mohammad Wasif Naqvi ◽  
Liang-Bo Hu
Keyword(s):  
Ground Motion ◽  
Seismic Waves ◽  
Response Spectrum ◽  
Time History ◽  
Centrifuge Model Test ◽  
Peak Time ◽  
Motion Response ◽  
Centrifuge Model ◽  
Amplification Effect ◽  
Stiff Soil

The ground motion response in a moderately stiff soil in seismic events has been traditionally studied based on the actual field records which, however, have yet to offer consistent results regarding the amplification effect of the ground motion. In the present study, a centrifuge model of the moderately stiff soil field is designed to study the amplification effect of the ground motion in response to seismic loads. Four El Centro waves of different strengths are used as the input wave at the base under a gravitational field of 75 g. Ground motion data at different depths are collected via a number of sensors to study the acceleration peak, time history, and response spectrum of the ground motion. The measured amplitude and energy of seismic waves are found to gradually increase from the bottom to the surface during the propagation of seismic waves, and the peak acceleration at the surface is significantly magnified. The response spectrum analysis shows that the acceleration response spectrum gradually moves to the high-frequency direction from the base to the surface and the value of the response spectrum decreases with the increase of the depth in the present study.

Dynamics of a Rod-Fastened Rotor Considering the Bolt Loosening Effect

2019 ◽  
Author(s):  
Pu Li ◽  
Qi Yuan ◽  
Bingxi Zhao ◽  
Jin Gao
Keyword(s):  
Dynamic Response ◽  
Gas Turbines ◽  
Equations Of Motion ◽  
Bending Moment ◽  
Extreme Condition ◽  
Superposition Method ◽  
Mode Superposition Method ◽  
Joint Element ◽  
Bolt Loosening ◽  
Fundamental Insight

Abstract Rod-fastened rotors are widely applied in heavy duty gas turbines and aircraft engines due to a good stiffness-to-weight behavior compared to conventional forged rotors. In order to achieve a continuous and stable power output, it is critical to guarantee the mechanical integrity. Therefore, the clamping force is of great importance which influences the distribution of the contact pressure. In an extreme condition, the bolt loosening resulting in an additional bending moment entails a different dynamic response. In this paper, the dynamics of a rod-fastened rotor subjected to the unbalance force, combined loads from the residual bow as well as the bolt loosening will be analyzed. First of all, an accurate rod-fastened rotor model is generated incorporating 1D beam element and zero-length joint element. Next, the mode superposition method is applied to derive the equations of motion and the analytical solution of the rod-fastened rotor will be achieved. Furthermore, experimental results are used to verify the simulations. It has demonstrated that the rod loosening yields a remarkably different behavior compared to the normal rotor after balancing. The dynamic response is also closely dependent on the unbalance as well as the relative phase angle between the location of unbalance and rod loosening. This paper provides a fundamental insight into the steady response of the rod-fastened rotor and may be used for fault identification as well as balancing of combined rotors.

Identification of Vehicle-Bridge Interactive Forces From Measured Bridge Responses: Theoretical Studies

1995 ◽  
Author(s):  
S. S. Law ◽  
Tommy H. T. Chan ◽  
Q. H. Zeng
Keyword(s):  
Time History ◽  
Bending Moment ◽  
Highway Bridges ◽  
Interaction Force ◽  
Superposition Method ◽  
Vibration Data ◽  
Moving Force ◽  
Modal Superposition Method ◽  
History Of ◽  
Bridge Responses

Abstract Information of the vehicle-bridge interaction force is an important parameter in the design and evaluation of highway bridges. However it is difficult to directly measure or accurately calculate the force which is a moving force. The objective of this paper is to explore the theory of force identification based on the response of the structure to acquire a time history of the moving force. The force will be identified in time domain using a modal superposition method. A moving force on a simply supported beam is simulated, and the computational results show that the method is noise sensitive, and yet acceptable results can be obtained by combining the use of vibration data of the bending moment and acceleration measurements.

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