Institute of Engineering Mechanics

Sanhe, China

Institute of Engineering Mechanics

Sanhe, China
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Luo Q.-Y.,Institute of Engineering Mechanics | Wang T.,Institute of Engineering Mechanics
Gongcheng Lixue/Engineering Mechanics | Year: 2017

In order to coordinate substructures with distinct physics in a hybrid test framework, this paper utilizes the interface element method to build up the overall stiffness matrix based on the general variational principle, where the statically condensed boundary stiffness matrices of substructures and the stiffness of interface elements are combined. This strategy makes the hybrid test more flexible particularly facing the substructures with different element types and meshes. Meanwhile, a transfer function was introduced to the method to correlate the subdomains with different numbers of degrees of freedom. Finally, the nonlinear time history analysis was conducted on the shell-beam model, which fully demonstrates the feasibility and the accuracy of the interface element method. © 2017, Engineering Mechanics Press. All right reserved.

Chen L.,Institute of Engineering Mechanics | Chen L.,Polytechnic of Milan | Faccioli E.,Polytechnic of Milan
Bulletin of Earthquake Engineering | Year: 2013

A systematic analysis was conducted of the different variability components that affect the prediction of log10(PSA) (i.e., Pseudo-Spectral Acceleration) ordinates on (mostly) deep sedimentary soil sites using a sizable set of strong motion data recorded in the strong earthquake sequences of 2010 and 2012 in the Canterbury region of New Zealand. Following recent, well established approaches of residual analysis of ground motion predictions, as well as recent GMPEs based on a global dataset, it was found that the event-corrected single-station standard deviation ("sigma") is strongly decreased, for all selected stations, with respect to the uncorrected sigma. Likewise, the event-corrected intraevent sigma estimated for the entire dataset is significantly reduced compared to the standard deviation associated to ground motion prediction models, i.e. the "ergodic" sigma, for all spectral periods. The event-corrected sigma values for the present dataset are surprisingly consistent with those recently derived using KiK-Net strong motion data from Japan and those by Boore and Atkinson (Earthq Spectra 34(1):99-138, 2008) GMPE, and remain fairly constant with respect to the spectral period at about 0.15 ~ 0.2. An interpretation was provided of the physical meaning of the site correction term (δ S2S)s indicating a plausible correlation with prevailing geological conditions in the site area. © 2013 Springer Science+Business Media Dordrecht.

Qi W.-H.,Institute of Engineering Mechanics | Bo J.-S.,Institute of Disaster Prevention | Liu H.-S.,Institute of Engineering Mechanics
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

The current formula can not calculate the fundamental periods of the sites containing soft soil layers accurately. In order to solve the problem, a fundamental period formula for a horizontal layered site, on which the effect of soil layer construction is considered, is deduced based on the vibration theory. According to the rules of natural vibration periods being equal, a single layer site is simplified into a SDOF system by means of the lumped mass method, and the equivalent height coefficient between their heights is deduced. A horizontal multi-layer site can be simplified into a SDOF system based on any one soil layer, and the height of the SDOF system is equal to that of the soil layer multiplied by the equivalent height coefficient. The natural vibration period of the SDOF system is called contributing fundamental period of the soil layer here, and the fundamental period of the site should be equal to the square root of sum square (SRSS) of the contributing fundamental periods of all the soil layers in the site, and its formula is also deduced. The test results show that (a) the proposed formula can reflect the effect of soil layer construction on fundamental periods of sites very well, and (b) by comparing the calculated fundamental periods with the test ones of 5 engineering sites by use of the microtremor method, the proposed formula is of higher accuracy and reliability than the current formula. A conclusion is drawn that the deduced formula can be adopted to estimate the fundamental period of a layered horizontal site.

Qu Z.,Institute of Engineering Mechanics | Shi X.,Institute of Engineering Mechanics
Gongcheng Lixue/Engineering Mechanics | Year: 2016

Although many efforts have been taken in the past years to study the near-fault ground motion observation and its effects on the seismic responses of building structures, the number of near-fault pulse-like ground motion records in mainland China is still very limited. The Mw6.3 Ludian earthquake in 2014 caused high fatality and severe building damages disproportional to its earthquake magnitude. Despite the insufficient seismic performance of the local buildings and the influence of secondary disasters, the significant near-fault pulse-like ground motion was another important factor. The velocity pulses in the Ludian Earthquake motion records are identified by a quantitative method incorporating wavelet transformation. The characteristics of these pulses are compared with those obtained in the 2008 Wenchuan Earthquake. The comparison shows the velocity pulse in the LLT record has much shorter period but higher peak velocity, which is rare for moderate earthquakes of magnitude about 6. Furthermore, directivity of the pulse energy distribution of the LLT record is observed. Further investigations are needed before attributing the significant velocity pulse to the forward directivity because the LLT station is too close to the epicenter. © 2016, Engineering Mechanics Press. All right reserved.

Chen L.,Institute of Engineering Mechanics | Wang W.,Institute of Engineering Mechanics | Yuan X.,Institute of Engineering Mechanics
Advanced Materials Research | Year: 2012

Characteristic site period is an important index in seismic zonantion and seismic resistance design. In seismic response spectrum theory, the characteristic design period is closely related with site characteristic site period which is comprehensively covering site parameters (site categories, site shear wave velocity, site thickness, etc.). Two models, i.e., single-layer model and double-layer model, are adopted and theoretical solutions are deduced by means of the amplification coefficient function. The natural site period are theoretically deduced and presented. © (2012) Trans Tech Publications, Switzerland.

Chen H.,Institute of Engineering Mechanics
13th International Conference on Fracture 2013, ICF 2013 | Year: 2013

Fracture analysis is a high non-linear problem and affected by uncertainties. Because of the limitation of observing technology, accuracy boundary condition can hardly be obtained. Normally, a stochastic model can be used. The difference between reality and numerical model is deemed as disturbance. This paper presents a three-dimension dynamic stability analysis of crack growth under disturbance in boundary condition by using particle discretization scheme finite element method. The model is a thin epoxy plate with two anti-symmetric notches located in the middle, under uni-axial tensile in longitudinal direction. Two types of disturbance are considered: (i), the disturbance is added to the initial cracks' configuration. The disturbance is modeled by adjusting the position, size and shape of the notches. It shows that changes of the notches' size and position have significant influence on crack growth in the investigated cases; (ii), the disturbance is applied to the displacement boundary condition, which is far from initial cracks. The variability of crack paths of different model sizes under the same disturbance is estimated. The results of the numerical experiment indicate that as the model size increases, the influence of the disturbance becomes weaker. The Saint-Venant principle still holds in the studied crack growth problem.. Copyright © (2013) by International Conference on Fracture.

Yang Q.,Institute of Engineering Mechanics | Shu Y.,Institute of Engineering Mechanics
World Information on Earthquake Engineering | Year: 2011

Waveform distortion is an important performance index of the standard vibration table. For standardizing measurement methods and instruments used in the testing, low-frequency distortion of the low-frequency vibration table is analyzed and distortion measurement methods are studied in experiment. The qualified limit description of the low-frequency distortion is proposed, and many experiments were done for testing the distortion measurement methods and the used instruments. The results provide reference for the low-frequency standard vibration table technical specifications, testing procedures and normalising distortion test method.

Tao Z.,Institute of Engineering Mechanics
International Journal of Digital Content Technology and its Applications | Year: 2012

Event study, which is popular in finance and accounting, is adopted to measure the effect of an earthquake on stock market. In the case of the 2011 off the Pacific coast of Tohoku Earthquake, the constant mean return model and the market model are adopted for the whole Japanese stock market and some typical stocks respectively. The result indicates that abnormal returns from the whole market are negative and significant, at level 0.01, only in the next four days of this event; however, in fourteen typical stocks of automobiles and motorcycles manufacture, electronic goods, transportation, lifeline and insurance, those from Tokyo Electric Power Company Inc., Honda Motor Co. Ltd., Nissan Motor Co. Ltd. and Fuji Heavy Industries Ltd. are negative and significant, at level 0.01, in the next ten days.

Qu Z.,Institute of Engineering Mechanics | Zhang L.,Institute of Engineering Mechanics
Journal of Earthquake Engineering and Engineering Vibration | Year: 2013

Reliable techniques for seismic retrofit of existing reinforced concrete structures are essential importante for improving the seismic performance of the buildings and promoting the sustained development of the society. Effective seismic performance evaluation and retrofitting methods for existing reinforced concrete structures have been developed in Japan through many decades of engineering practice and are helpful for improving the seismic retrofitting practice in China. Following a brief introduction to the retrofit design methods of Japan, the conventional retrofitting methods of reinforced concrete structures in Japan and their recent refinement are summarized in detail and the undergoing development in next-generation retrofitting methods are described with focuses on innovative techniques featuring attached external substructures, damage control and self-centering techniques.

Stasiuk G.,Institute of Engineering Mechanics
Key Engineering Materials | Year: 2012

The aim of the proposed studies is the development of the carbon/carbon composite with prescribed elastic properties. To achieve this, a microstructure optimisation problem for estimation of the microstructure with prescribed stiffness is formulated. The design variables of the posed problem are the local fibers distribution and porosity. The volume fractions of the fibers and pores in the whole microstructure are fixed. Material properties of the local microstructure of the composite are calculated using virtual models. Semi-analytical homogenization procedures were used for the development of these models. Modeling results are compared with elastic properties obtained experimentally by tension and compression test and ultrasonic studies of the bulk material. Approach to design microstructure for three point bending test is proposed. © (2012) Trans Tech Publications.

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