Modal Analysis of a Reinforced Concrete Frame in Various States of Damage

2005 ◽  
Vol 293-294 ◽  
pp. 735-742
Author(s):  
Zbigniew Zembaty ◽  
Marcin Kowalski
Keyword(s):  
Natural Frequencies ◽  
Visual Detection ◽  
Shaking Table ◽  
Structural Damping ◽  
State Characteristic ◽  
Reinforced Concrete Frame ◽  
Seismic Excitations ◽  
Concrete Frame ◽  
Natural Size ◽  
Working Out

The purpose of this paper is to report selected results of an experiment in which two, natural size r/c frames were put on shaking table and subjected to a sequence of seismic excitations with increasing intensity interlaced with low level, diagnostic tests. The shaking table experiment aimed at working out new methodology for monitoring vibrations of r/c structures to assess their state. Characteristic decrease of natural frequencies and increase of structural damping was observed and analyzed in detail. It was interesting to note 20 per cent drop in natural frequencies prior to visual detection of any cracks.

Seismic performance of a controlled rocking reinforced concrete frame

2016 ◽  
Vol 20 (1) ◽  
pp. 4-17 ◽  
Author(s):  
Liang Lu ◽  
Xia Liu ◽  
Junjie Chen ◽  
Xilin Lu
Keyword(s):  
Reinforced Concrete ◽  
Cyclic Loading ◽  
Seismic Performance ◽  
Shaking Table Test ◽  
Joint Stiffness ◽  
Shaking Table ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Metallic Dampers ◽  
Reversed Cyclic

A controlled rocking reinforced concrete frame is a new type of vibration control structure system that uses resilient rocking columns and joints. The effects of earthquakes on this type of structure are reduced by weakening the overall stiffness, whereas the lateral displacement is controlled by the energy-dissipation dampers introduced into the structure. Two tests were performed for research: the reversed cyclic loading test and shaking table test. Two single-span single-story controlled rocking reinforced concrete frames were designed for reversed cyclic loading tests. These tests (i.e. a column-base joint stiffness test, beam-column joint stiffness test, and frame stiffness test) were performed under different conditions. The mechanical analysis model of the rocking joints was derived from the test results. With the parameters obtained from the cyclic tests, a numerical simulation method that established the analytical model of the controlled rocking reinforced concrete frame using the program ABAQUS is proposed, and the dynamic time-history analysis results of the controlled rocking reinforced concrete frame and of the conventional approach are compared to investigate the vibration control effect and seismic performance of the controlled rocking reinforced concrete frame. In addition, the inter-story drift could be effectively controlled by adding metallic dampers, and the shaking table test models of the controlled rocking reinforced concrete frame with metallic dampers were designed and constructed. The comparison of the results of the numerical analysis and the shaking table test demonstrates that the model building of the controlled rocking reinforced concrete frame structure is efficient and that the controlled rocking reinforced concrete frame exhibits an excellent seismic performance.

Numerical Simulation of a RC Frame Shaking Table Test Model Based on CANNY

2010 ◽  
Vol 163-167 ◽  
pp. 981-986
Author(s):  
Li He ◽  
Xian Guo Ye
Keyword(s):  
Numerical Simulation ◽  
Shaking Table Test ◽  
Simulation Analysis ◽  
Shaking Table ◽  
Test Model ◽  
Rc Frame ◽  
Reinforced Concrete Frame ◽  
Element Analysis ◽  
Concrete Frame ◽  
History Of

This paper presents the nonlinear dynamic simulation analysis of a shaking table test specimen, which was a twelve- story reinforced concrete frame and tested under base excitations representing four earthquake records of increasing intensity. Owing to the length constraint of the paper, three cases are used for the simulation. The numerical simulation of the test model is conducted utilizing the finite element analysis procedure CANNY, and the analysis results include the natural frequency, response history of the frame and the damage evolution. It is concluded from comparisons between experimental results and the numerical simulation ones that the latter matches well with the former, therefore the validity of the analytical method and model for simulation of RC frame shaking table test is proved.

Application of FBG Sensors in Shaking Table Test of Frame-Shear Wall Structure Model

2010 ◽  
Vol 163-167 ◽  
pp. 2653-2656
Author(s):  
Li Sun ◽  
Hai Xia Zhang ◽  
De Zhi Liang ◽  
Zhe Li
Keyword(s):  
Transmission Lines ◽  
Shaking Table Test ◽  
Shear Wall ◽  
Shaking Table ◽  
Wall Structure ◽  
Structure Model ◽  
Reinforced Concrete Frame ◽  
Wall Model ◽  
Concrete Frame ◽  
Fbg Sensors

In this paper, FBG sensors are used to monitor and analyze the response of reinforced concrete frame-shear wall model in shaking table test in order to study the placement of sensors and the protection of the transmission lines. Based on the experiment data, the destructive mode and dynamic characteristics in earthquake are obtained through (by) analyzing the dynamic response of the structures. The experiment results show that using FBG is effective in monitoring the structures.

Vulnerability Assessment of Existing Low-Rise Reinforced Concrete School Buildings in Low Seismic Region Using Ambient Noise Method

2014 ◽  
Vol 931-932 ◽  
pp. 483-489 ◽  
Author(s):  
Ahmad Fahmy Kamarudin ◽  
Ibrahim Azmi ◽  
Zainah Ibrahim ◽  
Aziman Madun ◽  
Mohd Effendi Daud
Keyword(s):  
Reinforced Concrete ◽  
Vulnerability Assessment ◽  
Ambient Noise ◽  
Natural Frequencies ◽  
Structural Response ◽  
Reinforced Concrete Frame ◽  
Seismic Region ◽  
Concrete Frame ◽  
Adjacent Buildings ◽  
Ambient Noise Method

Ground movements triggered by the Bukit Tinggi earthquakes in 2007 to 2009 are believed to be the possible cause of several structural damages on a secondary school building of SMK Bukit Tinggi, in the state of Pahang, Malaysia. This paper describes the ambient noise study conducted on the damaged building (a 4-storey reinforced concrete frame laboratory building) and the adjacent buildings using tri-axial 1 Hz seismometer sensors. Fourier amplitude spectra (FAS) analysis was applied to determine the buildings natural frequencies for vulnerability assessment of the damaged structure in both longitudinal and transverse axes. Significant multiple peaks of FAS curves used for natural frequencies determination of the buildings show values between 4.18 to 4.34 Hz, 5.04 to 5.23 Hz, 6.07 to 6.54 Hz and 8.17 to 8.81 Hz, indicating the existence of translational and torsional vibration modes acting on the buildings. Differences in dynamic behaviour between the laboratory and the adjacent buildings may be responsible for the structural damages due to the independent structural response and excessive torsional effect during the Bukit Tinggi earthquake tremors.

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