Maximum Acceleration Values Research Articles

Hysteresis Envelope Model of Double Extended End-Plate Bolted Beam-to-Column Joint

In this study, a hysteresis envelope mathematical model for the double extended end-plate bolted beam-to-column joint is proposed. The aim of a proposed joint model is to provide a more realistic behaviour of steel frames under seismic loading by using nonlinear static pushover analysis. The hysteresis envelope model defines the ratios between the monotonic properties of the joints and the properties of the joints during cyclic deformation. The proposed models are based on the hysteresis curves of the joints obtained by numerical simulations. The numerical model takes into account the geometric nonlinearity of the connecting elements, preloading of bolts, contacts between plates and bolts, and nonlinear properties of steel. Nonlinear static pushover analyses of steel frames are performed where the behaviour of the joints is described using the proposed hysteresis envelope models. The results are compared with the nonlinear static pushover analyses of steel frames with a trilinear monotonic joint model. Based on the results, the values of maximum peak ground acceleration for moment-resisting frames with the monotonic model of joints and hysteresis envelope model are estimated.

Determination of Bearing Quality Using Frequency Vibration Analysis

Abstract The paper proposes two methods for determining the quality of industrially manufactured bearings, where the vibro-acoustic energy is expressed by measuring the vibration acceleration. The determined criteria were verified and 100 % agreement was reached in determining the required quality of the bearings. Unwanted bearing noise emissions and its faults can be monitored over the maximum acceleration value determined from the time history, the frequency distribution and the r.m.s. value of the determined frequency range.

Shallow seafloor seismic wave monitoring using 3-component fiber optic interferometric accelerometer

A fiber optic interferometric seismic monitoring system developed by us was deployed on the shallow seafloor near the Wuchang oceanic monitoring station off the Hainan Island, in the South China Sea, in 2017. In the past three plus years, it has recorded more than 40 teleseismic activities of magnitude 6.0+. We analyze these shallow seafloor observed seismic signals monitored by the fiber optic interferometric three-component accelerometer from the perspective of analyzing the underwater ambient seismic noise and the attenuation of the noise in the shallow seafloor seismic signals. The ambient seismic noise produced by wind, wave, shipping, and on-shore manmade activities admixed in the seismic signal is analyzed and discussed in detail. And the attenuation of such noise in the shallow seafloor seismic data using a hybrid denoising algorithm is demonstrated by applying it to three representative seismic events having different distances and magnitudes, with results showing that the noise in the shallow seafloor seismic signal is effectively reduced, and the ratio of the maximum acceleration value of seismic wave to the noise level is improved by more than 32 dB, rendering the seismic waves clearly observable.

Distribution of peak ground acceleration in Pandeglang Regency, Banten

Pandeglang Regency is an area prone to earthquakes because in the subduction zone of the Indo-Australian plate and the Eurasian plate in the Sunda Strait. This study analyses the average and maximum values of the Peak Ground Acceleration (PGA) got from earthquakes in the period 2000 to 2020 around Pandeglang Regency with the calculation method. Gutenberg-Richter with the Richter formula combined with the intensity attenuation formula which is a function of magnitude, epicentre distance, and earthquake intensity. From the maximum PGA data, the lowest value is 273 gals, and the highest is 427.5 gals. Meanwhile, for the distribution of the average PGA value, the minimum value is 54 gals, and the maximum value is 67 gals. From the PGA data, the maximum distribution of the highest PGA value is in the center of Pandeglang Regency, and the lowest value of the PGA maximum is in the northern and southern parts of Pandeglang Regency. The PGA value is potentially damaging at the VII MMI scale, where the area with the highest vulnerability is in the sub-district Angsana, Munjul, Panimbang, and Sidangresmi with the highest PGA scores, so this sub-district has the highest risk than other districts.

Onsite Early Prediction of PGA Using CNN With Multi-Scale and Multi-Domain P-Waves as Input

Although convolutional neural networks (CNN) have been applied successfully to many fields, the onsite earthquake early warning by CNN remains unexplored. This study aims to predict the peak ground acceleration (PGA) of the incoming seismic waves using CNN, which is achieved by analyzing the first 3 s of P-wave data collected from a single site. Because the amplitude of P-wave data of large and small earthquakes can differ, the multi-scale input of P-wave data is proposed in this study in order to let the CNN observe the input data in different scales. Both the time and frequency domains of the P-wave data are combined into multi-domain input, and therefore the CNN can observe the data from different aspects. Since only the maximum absolute acceleration value of the time history of seismic waves is the target output of the CNN, the absolute value of the P-wave time history data is used instead of the raw value. The proposed arrangement of the input data shows its superiority to the one directly inputting the raw P-wave data into the CNN. Moreover, the predicted PGA accuracy using the proposed CNN approach is higher than the one using the support vector regression approach that employed the extracted P-wave features as its input. The proposed CNN approach also shows that the accuracy of the predicted PGA and the alert performances are acceptable based on data from two independent and damaging earthquakes.

High-resolution probabilistic seismic hazard analysis of West Nusa Tenggara, Indonesia

The interest to build a nuclear power plant in West Nusa Tenggara Province has caused a concern related to the seismic hazard. One of the challenges was that the existing low-resolution national seismic hazard map did not cover the entire islands of West Nusa Tenggara Province. In this paper, preliminary probabilistic seismic hazard analysis of West Nusa Tenggara was performed to complement the existing national seismic hazard map for West Nusa Tenggara. The analysis was carried out using OQ software based on the seismotectonic model and GMPE developed by PUSGEN. Similar seismotectonic model and seismic event trees were implemented using a finer grid spacing of 500–1000 m. The seismotectonic model included active shallow crustal, subduction interface, and background sources with a total number of 50 seismogenic sources and was calculated using 108 GMPE paths. Two hazard levels were considered, each representing 1% and 2% POE in a 100-year return period. A comparison to the existing national seismic hazard map on the PGA level has been presented in this study and yielded a 13–25% difference in the ground acceleration value. Spectral hazard maps representing the shorter period (0.2 s) showed a maximum ground acceleration value of more than 2 g, especially in the northern part of Sumbawa Island. Beyond the longer spectral period (1 s), ground acceleration gradually decreases to the level below the PGA level.

Modeling of Criteria of Reliability of Vibrating Platforms for Compaction of Construction Mixtures

The main criteria of vibration reliability of vibration sites of the construction industry are considered. It is proposed that the simplest and most important measure of vibration stress is the maximum value of acceleration a(t), which was measured in absolute values, or in the dimensionless form of its attribution to the acceleration of gravity. One of the quality requirements is the maximum vibration acceleration, which at the points of the system does not exceed the maximum allowable values a(t). As the vibration stress is 10−3 m in the form of a vibration displacement of 20 m/s2, depending on the purpose of the elements of the vibrating machines, restrictions can be imposed on both absolute and relative displacements. Evaluate the magnitude of vibration stresses that occur in its elements, the strength of the system. The quality condition requires that the corresponding maximum stresses (in the case of a complex stress state – some maximum equivalent stresses) do not exceed the permissible values. Taken into account in the number of parameters of the quality of forces and moments occurring in the elements of the system, allows to calculate the bearing capacity of the elements. In any case, the vibration load over time leads to the failure of system elements, this is usually accompanied by the accumulation of relevant damage, so the most accurate approach to assessing the vibration reliability is based on consideration of the process of accumulation of damage.

Impact dynamic response of low damped structures subjected to impulse base accelerations

Shocks and impact loads are generated during the operational life of aerospace vehicles and their effects should be considered for the structural design and verification of these systems. Due to the complexity of assessing shock loads numerically, there is a lack of accurate methods to calculate the mechanical response under a shock environment. One of the existing approaches is the Response Spectrum Analysis, which directly estimates the maximum peak values of structural response accelerations generated by shocks, where it is necessary to define the input acceleration as a Shock Response Spectrum. This approach is based on the calculation of the modal contributions to the total maximum response, which can be combined in different ways, leading to a great variety of possible results for the same response. Furthermore, the existing options generally provide inaccurate results. The objective of this paper is the development and verification of a new method for the Response Spectrum Analysis approach to calculate accurately the peak response accelerations of undamped and low damped structures subjected to impulse base excitations characterized by a main pulse. The proposed method is verified in this paper by numerical analyses for a beam structure to demonstrate the improvement in the accuracy of the provided results compared to the existing options.

Analysis of excitation source characteristics and their contribution in a 2-cylinder diesel engine

Vibration signal of internal combustion engine is excited by the cylinder pressure and other excitations. The response signals caused by different excitations couple together in the time domain and frequency domain, which makes it difficult to extract combustion information from vibration signal. To determine the main excitation sources and the contribution level of the most important excitation that contributes to the vibration in a 2-cylinder diesel engine, the ratios of the maximum value of displacement, velocity and acceleration caused by the non-combustion excitations to those caused by the cylinder pressure are calculated. And a cylinder head-body finite element model of an SD2100TA diesel engine is established to analyze the characteristics of different excitations such as reciprocating inertial force (RIF), piston slap and main bearing load (MBL). According to the analyzed results, the excitations that play a major role on the vibration signal is determined. In addition, the coupling relationship of the excitations is evaluated. The simulation results show that the RIF is the most important excitation in the vibration signal. Finally, the contribution level of the RIF is calculated with the partial coherence function. Results show that the contribution level increases significantly with the increase of the rotation speed and remains basically unchanged with the increase of the torque.

Failure Mechanism of Rock Slopes under Different Seismic Excitation

In earthquake‐prone areas, special attention should be paid to the study of the seismic stability of rock slope. Particularly, it becomes much more complicated for the rock slopes with weak structural surfaces. In this study, numerical simulation and the shaking table test are carried out to analyze the influence of seismic excitation and structural surface in different directions on dynamic response of rock slope. Huaping slope with bedding structural surfaces and Lijiang slope with discontinuous structural surfaces besides Jinsha River in Yunnan Province are taken as research objects. The results of numerical simulation and the model test both show that discontinuous structure surface has influence on the propagation characteristics of seismic wavefield. For Huaping slope, the seismic wavefield responses repeatedly between the bedding structural surface and slope surface lead to the increase of the amplification effect. The maximum value of seismic acceleration appears on the empty surface where terrain changes. Horizontal motion plays a leading role in slope failure, and the amplification coefficient of horizontal seismic acceleration is about twice that of vertical seismic acceleration. The failure mode is integral sliding along the bedding structural surface. For Lijiang slope, seismic acceleration field affected by complex structural surface is superimposed repeatedly in local area. The maximum value of seismic acceleration appears in the local area near slope surface. And the dynamic response of slope is controlled by vertical and horizontal motion together. Under the seismic excitation with an intense of 0.336 g in X direction and Z direction, the amplification coefficients of seismic acceleration of Lijiang slope are 3.23 and 3.18, respectively. The vertical motion leads to the cracking of the weak structural surface. Then, Lijiang slope shows the toppling failure mode under the action of horizontal motion.

Аналіз експериментальних досліджень оптимального керування рухом механізмів повороту баштового крана та переміщення візка

The article analyzes the quality of the implementation of the optimal laws of simultaneous motion of the tower crane slewing and the trolley movement mechanisms. The estimation was carried out according to the maximum and root-mean-square values of the deviations of the theoretical and experimental characteristics. In addition, the graphical dependencies have been built. The data were estimated according to the characteristics of the speed of movement of the trolley and the rotation of the crane, as well as the angles of deflection of the load in the normal and tangential directions in the modes of acceleration and deceleration of the mechanisms. As a result of the analysis, it was found that the main reasons for the deviation of theoretical and experimental data on the characteristics under study are that the stiffness characteristics of the crane metal structure have not been taken into account, the parameters of the mechanisms are not accurately determined, and there are no feedbacks on the control characteristics (the speed of rotation of the crane and the speed of trolley movement). However, when implementing optimal control by means of a frequencycontrolled drive, pendulum oscillations of the load in the normal and tangential planes are eliminated. In addition, the analysis of the current loads of the drives of mechanisms and the acceleration of the crane boom was carried out. It was found that with optimal control, there is a significant decrease in the maximum values of acceleration, which means a decrease in dynamic loads on the crane metal structure. Also, the maximum currents in the motor windings of the crane mechanisms have been reduced, which, of course, will have a positive effect on the energy efficiency of the crane mechanisms.

Experimental and numerical simulation study on impact response of TC4/PEEK/Cf laminates under different mass impactors

Herein, the gas-gun test is combined with numerical simulations to study the impact response and damage modes of TC4/PEEK/Cf (Ti-6Al-4V alloy-based carbon fiber reinforced polyetheretherketone laminates) under different mass impactors. TC4/PEEK/Cf are orthogonally arranged, with a total thickness of 1.8 mm after hot pressing, the impactor is cylindrical with a diameter of 9 mm and different masses. The results showed that within a certain range, the decrease in ballistic limit became smaller with increasing impactor mass. Also, the residual velocity increase span gradually decreased from 29.6% to 2.4% at 2.98–3.97 g to 5.96–6.98 g, respectively. Moreover, the maximum value of acceleration attained a constant level with increasing impactor mass. Hence, the main damage modes of TC4/PEEK/Cf laminates consist of inter-laminar composite delamination, plastic deformation of metallic sheets and shear fracture. It is worth noting that the influence of impactor mass became irrelevant after a threshold value.

Assessment of Seismic Site Response and Liquefaction Potential for Some Sites using Borelog Data

Assessment of Liquefaction susceptibility of soil is very important aspect of disaster risk reduction for a particular region. The present research is an investigation to find out the liquefaction capability for the sites of Jalandhar and its surrounding region, Punjab (India) using semi empirical approach of Idris and Boulanger. Initially, the response of Ground has been analyzed with the help of DEEPSOIL software for evaluating the maximum ground acceleration values (PGASUR) at surface using five earthquake motions of magnitude, M = 6.0, 6.8 and 7.3 selected from worldwide recorded database based on seismicity of the region. The investigated PGA values ranges from 0.196 g to 0.292 g for the sites under investigation. Soil’s potential against liquefaction for 45 locations has been carried out using PGASUR results so obtained. It has been observed that eighteen sites out of forty-five are found to be susceptible to liquefaction. In order to help structural designers and geotechnical engineers for the preparation of realistic plan towards disaster risk reduction for the region, PGASUR contour map of obtained results and liquefaction hazard maps for earthquake of magnitude 6.0 and 7.0 has been prepared on geographical information system (GIS) platform using QGIS software. Doi: 10.28991/cej-2020-03091605 Full Text: PDF

Circular lining behaviour due to earthquake load in MRT Jakarta underground tunnel area CP-106

One solution to traffic congestion in Jakarta is to build a mass transportation system in the form of Mass Rapid Transit (MRT), especially the application of underground tunnel structures. This study examines the modeling of tunnel behavior on the effect of earthquake loads. This study calculates circular tunnel behavior in static and dynamic conditions due to earthquake effects. Static condition analysis using Muir Wood’s theory and dynamic conditions using the theories of Wang (1993) and Panzien (2000) as well as supported by empiric and numeric calculations. The depth of the MRT tunnel in the CP-106 area is at a depth of 11 meters by diverting by clay with NSPT 3-20. The results show that in static condition has tunnel deformation that works at 8.06 mm in empiric and 15.12 mm in numeric. In the dynamic analysis with earthquake acceleration in 300 cm/s2 produces oval deformation at 15.95 mm in empiric and 15.20 mm in numeric. The maximum deformation limit given is 20 mm with a maximum earthquake acceleration value of 400 cm/s2. In conclusion, MRT Jakarta area CP-106 in static condition has a lower deformation than dynamic conditions, but both conditions fulfill the deformation tunnel requirements.

Evaluation of impact-shock on gait after the implementation of two different training programs in older adults

BackgroundGait is negatively affected with increasing age. It is widely accepted that training produces physical-functional improvements in older adults, which can be assessed with numerous physical-functional tests. However, very few studies have been carried out using accelerometry to analyse the training effect on kinetic and kinematic variables in older adults, and there is no one that investigate the effects of two different training programs. Therefore, the aim of this study is to analyse the effects of an interval-walking program and a multicomponent program on the acceleration impacts, shock attenuation, step-length, stride frequency, and gait speed in older adults. Methods23 participants were divided into multicomponent training group [n = 12, 7 female, 71.58 (4.56) years] and interval-walking group [n = 11, 6 female, 69.64 (3.56) years]. We evaluated the participants using three triaxial accelerometers, placing one on the distal end of each tibia and one on the forehead. FindingsAfter 14 weeks' of training, the maximum acceleration values both for the head accelerometer and for the non-dominant tibia, as well as the attenuation in the same leg, increased in the multicomponent training group. The maximum acceleration values for the head and the stride frequency also increased in the interval-walking group. Lower limb strength improved in both groups. InterpretationGiven the benefits we found for each of these programs, we encourage their consideration when planning older adults training programs and suggest that multicomponent programs should be introduced prior to the start of walking-based programs.

Hawking-Unruh effect associated with primordial black holes and maximum acceleration of elementary particles

Three decades ago an expression for the maximum acceleration of elementary particles was derived using quantum theory. There is no experimental confirmation of this so far. In this paper we study the phenomenon of acceleration of elementary particles by the surface gravity of primordial black holes (PBH) formed in the early universe and the associated Hawking-Unruh effect. From a heuristic theory we find that every elementary particle can be associated with a PBH of unique mass and Hawking temperature. This implies a unique Hawking-Unruh acceleration for each elementary particle. The inferred values of maximum acceleration from our theory range from 6.24 × 1033 m/s2 for top quarks to 1.85 × 1028 m/s2 for electrons. These values can be considered to be the maximum acceleration given by the general expression mc32h of elementary particles of given rest mass (m) due to the force of gravity. Elementary particles with the maximum Compton wavelength (10−4 m) and an inferred mass of 0.0185 eV (possibly neutrinos) are found to be associated with a PBH whose Hawking temperature is identical to the cosmic microwave background temperature of the present Universe.

Influence of various parameters in the seismic soil-structure interaction response of a nuclear power plant

This paper presents a numerical study of the influence of various parameters on the seismic response of the CAREM-25 nuclear power plant (NPP) located in Argentina. The influence of soil stiffness, structure-soil-structure interaction (3SI), and infill soil stiffness are studied. Considering the available analysis capabilities, a full 3D methodology was adopted (direct method). Two soil profiles were used in order to quantify the influence of the soil on the structural response. An engineered rockfill was also used in order to study the influence of infill soil stiffness. Three artificial records with three components each were used as free field input. These records were obtained from the site design spectra. The turbo-group building was approximately modelled in order to consider 3SI. Finally, all live loads as well as the water in pools were included in the model. Design guides for this type of problem are given for all the elements of the model.When comparing flexible soil with stiff soil, important reductions of the maximum absolute acceleration value are obtained by flexible soil. Moreover, the horizontal maximum accelerations are remarkably amplified in height in the case of stiff soil. The influence of the proximity of the turbo-group building (3SI) on the dynamic response of the reactor building is negligible. Finally, the influence of infill soil stiffness is also negligible.

Understanding Metrics of Vehicle Control Take-Over Requests in Simulated Automated Vehicles

This paper derives an effective take-over alarm method for a Society of Automotive Engineers Level 3 automated vehicle using vehicle parameters. An experiment was conducted using a driving simulator. Forty-one subjects participated in two different scenarios: unplanned and planned operational design domain. Subjects drove on a highway at 100 km/h in automated mode. Experiment participants resumed manual control of the vehicle when the alarm was provided in the take-over state. A visual and auditory combined alarm was the most effective in terms of drivers’ cognitive load showing low steering angle deviation and steering reversal rate values compared to the combined visual, auditory, and haptic alarm (p = 0.01 and 0.003). The auditory alarm was the most effective in terms of the quality of the driver’s reaction showing a low maximum acceleration value compared to the combined visual, haptic alarm (p = 0.002). The combined visual, auditory, and haptic alarm was the most effective in terms of post-take-over lateral control showing a low standard deviation lateral position value compared to the haptic alarm (p < 0.001). The auditory and haptic combined alarm was the most effective in terms of post-take-over longitudinal control showing a low number of gas pedal inputs value compared to the haptic alarm (p = 0.002).

ANALISIS PENDUGAAN BAHAYA KEGEMPAAN DI BATUAN DASAR UNTUK WILAYAH LAMPUNG MENGGUNAKAN METODE PSHA

Analysis of seismic hazard estimation is one method for estimating the effect of earthquakes. The purpose of this study was to determine the maximum value of ground acceleration in bedrock or PGA values for the Lampung Province region. This analysis of seismic hazard estimation is carried out by a probabilistic seismic hazard analysis (PSHA) method. In the process of estimating the influence of earthquakes, the PSHA method principally uses 3 types of earthquake sources, namely the source of background earthquakes, subduction earthquakes (earthquake subduction) and fault earthquakes (faut). The calculation of the estimated seismic hazard value is carried out using the 2007 USGS PSHA program. The distribution of seismic hazard values for the Lampung Province region on bedrock with a 500-year return period or a 10% probability on the PGA condition (T = 0) is 0.1 g to 1, 3 g and a 2500 year return period or a probability of 2% in the PGA condition (T = 0) is 0.1 g to 1.3 g.

Experimental and analytical study on sliding vibration of a solid body

It is accepted that the use of base isolation systems within a structure offers a decreased amount of maximum acceleration value throughout the structure and provides a higher level of comfort and safety to the residents even during extremely strong ground motions. We want to propose a new low-cost structural system with the aforementioned benefits of the base isolation. A structural model was developed using an ultra-high-molecular-weight polyethylene film as a friction surface for the whole concrete base of a residential house, creating a friction-based base-isolation system. To understand the friction behavior between the two materials, a computer model was developed in SAP2000 software, and experiments were conducted to confirm the computer model’s proposed behavior. The created computer model is capable of accounting for the adjustments of the dynamic and static friction parameters depending on the velocity of the block. It is possible to conduct the numerical analysis with three-directional input to the system as well as nonlinear solving capabilities. The results of the numerical analysis are compared with the experiment results on a one-directional wave, along with the 1995 Kobe Earthquake ground motion record that had an input in three directions. The results confirm the reproducibility and predictable behavior of the proposed base-isolation method. The maximum acceleration of the concrete base will be no greater than nearly 30% of gravity acceleration regardless of the maximum acceleration of the ground motion.