The Pseudo Dynamic Test of RC Bridge Columns Analyzed Through the Hilbert-Huang Transform

2003 ◽  
Vol 19 (3) ◽  
pp. 373-387
Author(s):  
Y.-F. Li ◽  
S.-Y. Chang ◽  
W.-C. Tzeng ◽  
K. Huang

AbstractIn this paper, the analysis of the responses of the pseudo dynamic test of two rectangular reinforced concrete (RC) bridge columns using the Hilbert-Huang transform (HHT) is introduced. Firstly, two 40%-scaled rectangular RC bridge columns are subjected to the pseudo dynamic test. The input of the pseudo dynamic test is set as the near-fault ground accelerations of the Chi-Chi Earthquake, which happened in 1999 in central Taiwan. After damage occurs to the bridge columns, we use non-shrinkage mortar to repair the columns, and then use 3 layers of CFRP to rehabilitate their plastic zone. The repaired bridge columns are again tested. Then we use the HHT to analyze the responses of the as-built and repaired bridge columns. The merit of applying the HHT to the responses of bridge columns is that it can transfer the displacement-time responses into instantaneous frequency responses, while the spectra are a function of both frequency and time. We can observe from the Hilbert spectra of the bridge columns that, at the instant when the frequency changes, the structural behavior changes from elastic to inelastic. The HHT can therefore be used to obtain the instantaneous natural frequencies of the bridge columns and to understand the relationship between the frequency changes and stiffness condition of the bridge columns.

2011 ◽  
Vol 492 ◽  
pp. 410-414 ◽  
Author(s):  
Xiao Gen Liu ◽  
Yi Wang Bao

Developing efficient onsite damage detection and safety evaluation methods for glass curtain wall is still a challenging task. In this work, a simple approach to predict the failure and risk of falling down of curtain wall glass was developed through the relationship between the natural frequency changes and the declined reliability of the structures. Natural frequencies of the curtain wall glass under various clamping conditions were determined using dynamic tests. It was discovered that, with the decrease of the clamping force at the boundary of the glass specimen, the measured natural frequencies decreased linearly. Thus, the in-service capacity in edge clamping (e.g. boundary is loosed or failure of the supporting structure) of the curtain wall glass can be identified by its natural frequency changes. The expected lowest safety natural frequency of a curtain wall glass (given elastic parameters, shape and size) is given. The implementation of this detection method is described, and the practicability and feasibility validated.


2013 ◽  
Vol 351-352 ◽  
pp. 1043-1046
Author(s):  
Gang Xue ◽  
Chong Ge Wang

In order to study the relationship between prestress and natural frequencies and the factors of influence natural frequence change, a dynamic test on three simply supported externally prestressed concrete beams of different prestressed level was carried out. The results showed that the eccentricity and arrangement of externally prestressed tendons and the constraints have more influence on natural frequencies than prestress itself. The prestressed effect comes from combined action of the several factors, and the natural frequencies of beams were found to agree well with the prestress. It appears that higher order frequencies have greater increment usually.


2015 ◽  
Vol 1 (1) ◽  
Author(s):  
Cholida Khusnul Chotimah

ABSTRAKHasil belajar (prestasi belajar) merupakan perubahan perilaku yang diperoleh seseorang setelah mengalami aktivitas belajar. Perolehan aspek-aspek perubahan perilaku tersebut tergantung pada apa yang dipelajari oleh seseorang. Berhasil atau tidaknya seseorang untuk belajar disebabkan beberapa faktor yang mempengaruhi dalam pencapaian hasil belajar (prestasi belajar) yaitu berasal dari dalam diri orang yang belajar dan ada pula yang dari luar dirinya. Banyak faktor yang mempengaruhinya, diantaranya adalah motivasi dan minat. Tujuan dari penelitian ini adalah untuk mengetahui hubungan motivasi dan minat masuk Program Studi D  III Kebidanan dengan prestasi belajar mahasiswa  STIKES Insan Cendekia Husada Bojonegoro. Jenis penelitian ini adalah analitik korelasi. Penelitian ini menggunakan pendekatan cross sectional. Populasi dalam penelitian ini adalah semua mahasiswa Program Studi D III Kebidanan STIKES Insan Cendekia Husada Bojonegoro sebanyak 39 mahasiswa dengan  teknik total sampling dengan jumlah sampel 39. Penelitian ini menggunakan instrumen berupa kuesioner. Analisis hubungan variabel dilakukan dengan menggunakan Yates Correction. Hasil penelitian ini menunjukkan bahwa ada hubungan antara motivasi masuk Program Studi D III Kebidanan dengan prestasi belajar mahasiswa           (ρ =0,027) dan ada hubungan antara minat masuk Program Studi D III Kebidanan dengan prestasi belajar mahasiswa (ρ =0,044). Saran untuk Program Studi D III Kebidanan STIKES Insan Cendekia Husada Bojonegoro agar meningkatkan prestasi belajar mahasiswa Prodi D III kebidanan STIKES Insan Cendekia Husada Bojonegoro dengan cara dosen atau pembimbing akademik menciptakan kondisi pembelajaran yang menarik, sarana prasarana yang menunjang, hubungan antara dosen dan mahasiswa yang baik, sehingga mahasiswa terdorong untuk butuh dan terus belajar dan melakukan pemantauan dan pendekatan lebih dalam terhadap mahasiswa tentang tujuan mereka untuk masuk di Program Studi D III Kebidanan. Kata Kunci : Motivasi, minat, prestasi belajar  ABSTRACT      Results of learning (learning achievement) is obtained by a person's behavior changes after experiencing learning activities. Acquisition aspects of the behavior change depending on what is learned by someone. Success or failure of someone to learn due to several factors that affect the achievement of learning outcomes (learning achievement) that comes from within the person who studied and some are from outside himself. Many factors influence it, such as motivation and interest. The purpose of this study was to determine the relationship of motivation and interest in D III Midwifery Studies Program with student achievement STIKES Insan Scholar Husada Bojonegoro. This type of research is analytic correlation. This study used cross sectional approach. The population in this study were all students of the D III Midwifery STIKES Insan Husada Bojonegoro Scholar at least 39 students with a total sampling with a sample of 39. This study used a questionnaire instrument. Variable correlation analysis done using Yates Correction. Results of this study indicate that there is a relationship between motivation incoming D III Midwifery Studies Program with student achievement (ρ = 0.027) and there is a correlation between interest in D III Midwifery Studies Program with student achievement (ρ = 0.044). Suggestions for Study Program D III Midwifery STIKES Insan Scholar Husada Bojonegoro in order to increase student achievement Prodi DIII midwifery personnel STIKES Scholar Husada Bojonegoro by way of a professor or academic supervisor creates an attractive learning conditions, infrastructure that support, the relationship between faculty and students good , so that students are encouraged to take and continue to learn and perform monitoring and deeper approach to the students about their goals for entry in the D III Midwifery Studies Program. Key Words : Motivation, interests, academic achievement


Author(s):  
Victor Ei-Wen Lo ◽  
Yi-Chen Chiu ◽  
Hsin-Hung Tu

Background: There are different types of hand motions in people’s daily lives and working environments. However, testing duration increases as the types of hand motions increase to build a normative database. Long testing duration decreases the motivation of study participants. The purpose of this study is to propose models to predict pinch and press strength using grip strength. Methods: One hundred ninety-eight healthy volunteers were recruited from the manufacturing industries in Central Taiwan. The five types of hand motions were grip, lateral pinch, palmar pinch, thumb press, and ball of thumb press. Stepwise multiple linear regression was used to explore the relationship between force type, gender, height, weight, age, and muscle strength. Results: The prediction models developed according to the variable of the strength of the opposite hand are good for explaining variance (76.9–93.1%). Gender is the key demographic variable in the predicting models. Grip strength is not a good predictor of palmar pinch (adjusted-R2: 0.572–0.609), nor of thumb press and ball of thumb (adjusted-R2: 0.279–0.443). Conclusions: We recommend measuring the palmar pinch and ball of thumb strength and using them to predict the other two hand motions for convenience and time saving.


1995 ◽  
Vol 24 (12) ◽  
pp. 1623-1643 ◽  
Author(s):  
Mervyn J. Kowalsky ◽  
M. J. Nigel Priestley ◽  
Gregory A. MacRae

2014 ◽  
Vol 19 (5) ◽  
pp. 1456-1467 ◽  
Author(s):  
Jae-Hoon Lee ◽  
Jin-Ho Choi ◽  
Do-Kyu Hwang ◽  
Im-Jong Kwahk

2016 ◽  
Vol 9 (6) ◽  
pp. 842-855 ◽  
Author(s):  
J. R. BUENO ◽  
◽  
D. D. LORIGGIO ◽  

Abstract This article examines numerically the flexibility influence of support beams in static response and dynamic properties of a symmetric plate formed by massive slabs of reinforced concrete in elastic linear regime, using the Finite Element Method. In the static response the variation of bending mo-ments and displacements are evaluated, which depend on the relationship between the flexibility of the slab and the beam. The evaluation of dynamic properties is held in undamped free vibration, through which the vibration modes and the values of the natural frequencies is obtained, which are compared with the limits of the Brazilian standard code for design of concrete structures. Results show that the response may show great variation due to the change in the relationship between bending stiffness of the slabs and the beams.


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