JournalTOCs

Earthquake Engineering and Engineering Vibration
Journal Prestige (SJR): 0.479

Citation Impact (citeScore): 1
Number of Followers: 8

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1993-503X - ISSN (Online) 1671-3664
Published by Springer-Verlag

[2469 journals]

Geotechnical engineering blasting: a new modal aliasing cancellation
methodology of vibration signal de-noising
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  Abstract: Abstract In the present study of peak particle velocity (PPV) and frequency, an improved algorithm (principal empirical mode decomposition, PEMD) based on principal component analysis (PCA) and empirical mode decomposition (EMD) is proposed, with the goal of addressing poor filtering de-noising effects caused by the occurrences of modal aliasing phenomena in EMD blasting vibration signal decomposition processes. Test results showed that frequency of intrinsic mode function (IMF) components decomposed by PEMD gradually decreases and that the main frequency is unique, which eliminates the phenomenon of modal aliasing. In the simulation experiment, the signal-to-noise (SNR) and root mean square errors (RMSE) ratio of the signal de-noised by PEMD are the largest when compared to EMD and ensemble empirical mode decomposition (EEMD). The main frequency of the de-noising signal through PEMD is 75 Hz, which is closest to the frequency of the noiseless simulation signal. In geotechnical engineering blasting experiments, compared to EMD and EEMD, the signal de-noised by PEMD has the lowest level of distortion, and the frequency band is distributed in a range of 0–64 Hz, which is closest to the frequency band of the blasting vibration signal. In addition, the proportion of noise energy was the lowest, at 1.8%.
  PubDate: 2022-04-01
Measurement of vibration frequencies of ties in masonry arches by means of
a robotic total station
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  Abstract: Abstract Measurement of the vibration frequencies of eight ties set in masonry arches of a church by means of a robotic total station is described. The instrument made continuous recordings (up to ten per second) of the three-dimensional positions of a reflector situated at 1/2 or 1/4 of the length of the tie during vertical oscillation induced by an impulsive load. The recording slips, vibration amplitudes (and their accuracy), hourly diagram and experimental spectra of vibrations, and the corresponding frequencies were calculated. The results were verified by comparing them with the vibration frequencies and indirectly the tension and fixed support constraint calculated from accelerometric measurements. The study provides interesting information on the accuracies of the reflector’s three-dimensional coordinates, but highlighted certain limits in the application of robotized total stations for measuring vibration frequencies of ties in masonry arches.
  PubDate: 2022-04-01
Field measurement and evaluation of vibration in different areas of a
metro depot
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  Abstract: Abstract This paper presents a study of the characteristics of a railway vibration at three key sections containing different track structures in a metro depot. The results show that the vertical and horizontal vibration acceleration levels are proportional to train speed. The Z-weighted vertical acceleration levels obtained showed that the vibration source strengths at the ballast foot of the testing line and the throat area were very close. The vibration attenuation at the repair line was larger than that of the testing line. In the throat area, the peak frequency of vibration obtained at the ballast foot (2.5 m) could be shifted to a lower frequency band by using polyurethane sleepers instead of standard concrete sleepers. Polyurethane sleepers can help to reduce vertical vibration in a frequency band of 0–10 Hz. The vibration levels would satisfy the limits given in the ISO2631-2-2003 (2013) for any location more than 5 m away from the source at the testing line and 2.5 m away from the source at the repair line and throat area.
  PubDate: 2022-04-01
Performance-based global reliability assessment of a high-rise frame-core
tube structure subjected to multi-dimensional stochastic earthquakes
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  Abstract: Abstract When evaluating the seismic safety and reliability of complex engineering structures, it is a critical problem to reasonably consider the randomness and multi-dimensional nature of ground motions. To this end, a proposed modeling strategy of multi-dimensional stochastic earthquakes is addressed in this study. This improved seismic model has several merits that enable it to better provide seismic analyses of structures. Specifically, at first, the ground motion model is compatible with the design response spectrum. Secondly, the evolutionary power spectrum involved in the model and the design response spectrum are constructed accordingly with sufficient consideration of the correlation between different seismic components. Thirdly, the random function-based dimension-reduction representation is applied, by which seismic modeling is established, with three elementary random variables. Numerical simulations of multi-dimensional stochastic ground motions in a specific design scenario indicate the effectiveness of the proposed modeling strategy. Moreover, the multi-dimensional seismic response and the global reliability of a high-rise frame-core tube structure is discussed in detail to further illustrate the engineering applicability of the proposed method. The analytical investigations demonstrate that the suggested stochastic model of multi-dimensional ground motion is available for accurate seismic response analysis and dynamic reliability assessment of complex engineering structures for performance-based seismic resistance design.
  PubDate: 2022-04-01
Development of hybrid optimization algorithm for structures furnished with
seismic damper devices using the particle swarm optimization method and
gravitational search algorithm
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  Abstract: Abstract Previous studies about optimizing earthquake structural energy dissipation systems indicated that most existing techniques employ merely one or a few parameters as design variables in the optimization process, and thereby are only applicable only to simple, single, or multiple degree-of-freedom structures. The current approaches to optimization procedures take a specific damper with its properties and observe the effect of applying time history data to the building; however, there are many different dampers and isolators that can be used. Furthermore, there is a lack of studies regarding the optimum location for various viscous and wall dampers. The main aim of this study is hybridization of the particle swarm optimization (PSO) and gravitational search algorithm (GSA) to optimize the performance of earthquake energy dissipation systems (i.e., damper devices) simultaneously with optimizing the characteristics of the structure. Four types of structural dampers device are considered in this study: (i) variable stiffness bracing (VSB) system, (ii) rubber wall damper (RWD), (iii) nonlinear conical spring bracing (NCSB) device, (iv) and multi-action stiffener (MAS) device. Since many parameters may affect the design of seismic resistant structures, this study proposes a hybrid of PSO and GSA to develop a hybrid, multi-objective optimization method to resolve the aforementioned problems. The characteristics of the above-mentioned damper devices as well as the section size for structural beams and columns are considered as variables for development of the PSO-GSA optimization algorithm to minimize structural seismic response in terms of nodal displacement (in three directions) as well as plastic hinge formation in structural members simultaneously with the weight of the structure. After that, the optimization algorithm is implemented to identify the best position of the damper device in the structural frame to have the maximum effect and minimize the seismic structure response. To examine the performance of the proposed PSO-GSA optimization method, it has been applied to a three-story reinforced structure equipped with a seismic damper device. The results revealed that the method successfully optimized the earthquake energy dissipation systems and reduced the effects of earthquakes on structures, which significantly increase the building’s stability and safety during seismic excitation. The analysis results showed a reduction in the seismic response of the structure regarding the formation of plastic hinges in structural members as well as the displacement of each story to approximately 99.63%, 60.5%, 79.13% and 57.42% for the VSB device, RWD, NCSB device, and MAS device, respectively. This shows that using the PSO-GSA optimization algorithm and optimized damper devices in the structure resulted in no structural damage due to earthquake vibration.
  PubDate: 2022-04-01
Seismic performance evaluation of VCFPB isolated storage tank using
real-time hybrid simulation
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  Abstract: Abstract Variable curvature friction pendulum bearings (VCFPB) effectively reduce the dynamic response of storage tanks induced by earthquakes. Shaking table testing is used to assess the seismic performance of VCFPB isolated storage tanks. However, the vertical pressure and friction coefficient of the scaled VCFPB in the shaking table tests cannot match the equivalent values of these parameters in the prototype. To avoid this drawback, a real-time hybrid simulation (RTHS) test was developed. Using RTHS testing, a 1/8 scaled tank isolated by VCFPB was tested. The experimental results showed that the displacement dynamic magnification factor of VCFPB, peak reduction factors of the acceleration, shear force, and overturning moment at bottom of the tank, were negative exponential functions of the ratio of peak ground acceleration (PGA) and friction coefficient. The peak reduction factors of displacement, acceleration, force and overturning moment, which were obtained from the experimental results, are compared with those calculated by the Housner model. It can be concluded that the Housner model is applicable in estimation of the acceleration, shear force, and overturning moment of liquid storage tank, but not for the sliding displacement of VCFPBs.
  PubDate: 2022-04-01
Seismic behavior of multiple reinforcement, high-strength concrete
columns: experimental and theoretical analysis
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  Abstract: Abstract This study investigates the seismic performance of multiple reinforcement, high-strength concrete (MRHSC) columns that are characterized by multiple transverse and longitudinal reinforcements in core areas. Eight MRHSC columns were designed and subjected to a low cycle, reversed loading test. The response, including the failure modes, hysteretic behavior, lateral bearing capacity, and displacement ductility, was analyzed. The effects of the axial compression ratio, stirrup form, and stirrup spacing of the central reinforcement configuration on the seismic performance of the columns were studied. Furthermore, an analytical model was developed to predict the backbone force-displacement curves of the MRHSC columns. The test results showed that these columns experienced two failure modes: shear failure and flexure-shear failure. As the axial compression ratio increased, the bearing capacity increased significantly, whereas the deformation capacity and ductility decreased. A decrease in the spacing of central transverse reinforcements improved the ductility and delayed the degradation of load-bearing capacity. The proposed analytical model can accurately predict the lateral force and deformations of MRHSC columns.
  PubDate: 2022-04-01
Seismic behavior of precast segmental column bridges under near-fault
forward-directivity ground motions
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  Abstract: Abstract Precast segmental column bridges exhibit various construction advantages in comparison to traditional monolithic column bridges. However, the lack of cognitions on seismic behaviors has seriously restricted their applications and developments. In this paper, comprehensive investigations are conducted to analyze the dynamic characteristics of precast segmental column bridges under near-fault, forward-directivity ground motions. First, the finite-element models of two comparable bridges with precast segmental columns and monolithic columns are constructed by using OpenSees software, and the nonlinearities of the bridges are considered. Next, three different earthquake loadings are meticulously set up to handle engineering problems, namely recorded near- and far-field ground motions, parameterized pulses, and pulse and residual components extracted from real records. Finally, based on the models and earthquake sets, extensive explorations are carried out. The results show that near-fault forward-directivity ground motions are more threatening than far-field ones; precast segmental column bridges may suffer more pounding impacts than monolithic bridges; the “narrow band” effect caused by near-fault, forward-directivity ground motions may occur in bridges with shorter periods than pulse periods; and pulse and residual components play different roles in seismic responses.
  PubDate: 2022-04-01
Dynamic shear modulus and damping ratio characteristics of undisturbed
marine soils in the Bohai Sea, China
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  Abstract: Abstract This paper presents results from a series of stress-controlled undrained cyclic triaxial tests on the undisturbed marine silty clay, silt, and fine sand soils obtained from the Bohai Sea, China. Emphasis is placed on the major factors for predominating the dynamic shear modulus (G) and damping ratio (λ) in the shear strain amplitude (γa) from 10−5 to 10−2, involving depth, sedimentary facies types, and water content of marine soils. The empirical equations of the small-strain shear modulus (Gmax) and damping ratio (λmin) using a single-variable of depth H are established for the three marine soils. A remarkable finding is that the curves of shear modulus reduction (G/Gmax) and the damping ratio (λ) with increasing γa of the three marine soils can be simply determined through a set of explicit expressions with the two variables of depth H and water content W. This finding is validated by independent experimental data from the literature. At the similar depths, the G value of the marine soils of terrestrial facies is the largest, followed by the neritic facies, and the G value of the marine soils of abyssal facies is the smallest. The sedimentary facies types of the marine soils have slight effect on the λ value. Another significant finding is that the shear modulus reduction curves plotted against the γa of the three marine soils at the similar depths are significantly below those of the corresponding terrigenous soils, while the damping curves plotted against γa are just the opposite. The results presented in this paper serve as a worthful reference for the evaluation of seabed seismic site effects in the Bohai Sea due to lack of experimental data.
  PubDate: 2022-04-01
Decentralized damage diagnostic technique for tall buildings using VARMAX
model
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  Abstract: Abstract Civil infrastructure, especially buildings, are becoming more slender, tall, and multipurpose, creating a need to continuously monitor their health to ensure the safety and security of human lives and assets. While the majority of structural health monitoring techniques use measurements from the entire structure, in this study, an output-only damage diagnostic technique using a decentralized concept (subdomain-based) for tall buildings and employing a vector form of the autoregressive moving average with exogenous input (VARMAX) model is proposed, which offers reduced instrumentation and data handling requirements. Unlike other decentralized approaches, this technique predicts more than one DOF at a time so the number of subdomains required for the diagnosis of the complete structure is minimized. The proposed subdomain-based damage diagnostic algorithm works with ambient loads and does not require any correlated numerical models since it is solely based on measured data. The proposed algorithm can identify the time instant of damage, spatial location (s) and characterize the damage intensity. Efforts have been made to account for confounding factors such as environmental and operational variabilities separate from measurement noise to avoid false positive alarms. The effectiveness of the proposed technique is illustrated using synthetic time history responses from a twenty-story framed structure under ambient loading and an experimental study on a ten-story framed structure. Both numerical and experimental investigations confirm the effectiveness of the method and its robustness to environmental/operational variabilities and measurement noise.
  PubDate: 2022-04-01
Centrifuge modelling of ground-borne vibrations induced by railway traffic
in underground tunnels
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  Abstract: Abstract Increased attention has been given to ground-borne vibrations induced by railway vehicles and to the effects of these vibrations as they propagate through the ground into nearby buildings. Various studies, mainly based on numerical methods as well as physical modelling, have been carried out to investigate this problem. To study the dynamic response of tunnels and the surrounding soil due to train-induced vibration loads, a centrifuge test was conducted with a small-scale model in 1 g and 50 g stress field environments. An aluminum tube was embedded in sand to model the underground tunnel. A small parallel pre-stressed actuator (PPA) was employed to apply vibration loads on the tunnel invert. The model responses were measured using accelerometers. Both time and frequency domain analyzes were performed. The test results demonstrated that electronic noise had a clear impact on the test results and should be eliminated. It also found that the dynamic response of both the tunnel and soil were affected by the stress field. Therefore, it is important to account for the stress field effects when assessing the ground-borne vibration from tunnels.
  PubDate: 2022-04-01
Numerical study of a multiple post-tensioned rocking wall-frame system for
seismic resilient precast concrete buildings
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  Abstract: Abstract A multiple rocking wall-frame (MRWF) system, in which the wall panels are directly connected to the adjacent beams and foundation is presented herein. In the MRWF system, the unbonded post-tensioned (PT) tendons are used to promote the self-centering ability, and O-shaped steel dampers are applied to enhance the energy dissipation capacity and reparability of the structure. First, analytical equations are proposed to determine the behavior of the O-shaped dampers. Then, the MRWF system is numerically evaluated for five different models consisting of rocking walls with varying numbers and arrangements while keeping the total effective width of wall panels constant. The numerical results show that with an increase in the number of wall panels and a decrease in the wall width, the hysteretic behavior of the MRWF system tends to the ideal flag-shaped pattern, resulting in little damage to the beams, insignificant strain in the wall toe, negligible residual drifts and damage index of less than 0.2 under severe earthquakes. In contrast, the conventional model demonstrates extensive damage to the structural elements due to undesirable wall-to-frame interaction, which leads to a damage index of 0.78 and residual drifts of 0.42% under seismic loads.
  PubDate: 2022-04-01
Seismic behavior assessment for design of integral abutment bridges in
Illinois
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  Abstract: Abstract Integral abutment bridges (IABs) minimize deterioration and degradation of the abutment seats and bearings due to water, dirt, and deicing chemicals by eliminating bearings and expansion joints. Although the continuity between superstructure and abutments in an IAB is beneficial for reducing maintenance costs, it leads to more complex behavior under strength and service loading (temperature and traffic) and extreme loading (earthquake). The coupling of superstructure and substructure behavior necessitates system-level analysis of IABs. Prior seismic IAB studies have typically investigated the behavior of individual IAB components, however a gap of knowledge has developed due to the lack of studies and investigation about the behavior of all IAB components and their interactions with each other in a single analysis model. This study uses nonlinear static and dynamic analyses to investigate and assess the seismic behavior of IABs typical to the state of Illinois. The analyses aim to bridge the gap of knowledge by evaluating IABs as a whole and utilizing the results to indicate potential vulnerabilities in the design and construction of IABs in Illinois during design-level and larger seismic events, which could not be identified by component-level IAB analyses alone.
  PubDate: 2022-04-01
Range of applicability of real mode superposition approximation method for
seismic response calculation of non-classically damped industrial
buildings
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  Abstract: Abstract An industrial building is a non-classically damped system due to the different damping properties of the primary structure and equipment. The objective of this paper is to quantify the range of applicability of the real model superposition approximation method to the seismic response calculation of industrial buildings. The analysis using lumped mass-and-shear spring models indicates that for the equipment-to-structure frequency ratios γf > 1.1 or γf < 0.9, the non-classical damping effect is limited, and the real mode superposition approximation method provides accurate estimates. For 0.9 < γf < 1.1, the system may have a pair of closely spaced frequency modes, and the non-zero off-diagonal damping terms have a non-negligible effect on the damping ratios and mode shape vectors of these modes. For 0.9 < γf < 1.1 and the equipment-to-structure mass ratios γm < 0.07, the real mode superposition approximation method results in large errors, while the approximation method can provide an accurate estimation for 0.9 < γf <1.1 and γm > 0.07. Furthermore, extensive parametric analyses are conducted, where both steel structures and reinforced concrete structures with equipment with various damping ratios are considered. Finally, the finite element analysis of a five-story industrial building is adopted to validate the proposed range of applicability.
  PubDate: 2022-02-04
Optimal design of inerter systems for the force-transmission suppression
of oscillating structures
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  Abstract: Abstract When dealing with the oscillations of fixed-base structures or machines induced by external forces, suppressing the vibrational impact on the adjacent structures and the environment helps to maintain the structural durability and ensure the users’ comfort level. This study proposed an inerter-based optimal solution to suppress the vibrational forces and energy transmitted to the supporting ground by utilizing the great potential of the inerter. For the external force, which contains various frequency bands, the stochastic response and an energy balance analysis are conducted to evaluate the force transmissibility, structural displacement, and vibration power flow. Given the benefits of the inerter, a transmitted-force-based optimal design framework is proposed for inerter systems, of which the effectiveness is validated by numerical examples. The obtained results show that inerter systems are capable of providing significant reductions in the structural displacement and the force transmitted to the supporting ground. Particularly, the closed-form power equation indicated that a grounded inerter can suppress the force transmission and vibrational energy, thus leading to a less negative impact on the ground and environment. Revealing the working mechanism and optimal design strategy of the inerter can help solve the force-transmission control problem experienced by some practical structures.
  PubDate: 2022-02-04
Application of buckling-restrained braces in the seismic control of
suspension bridges
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  Abstract: Abstract Buckling-restrained braces (BRBs) are widely used to improve the seismic performance of buildings. This paper aims to introduce BRBs to suspension bridges and assess the seismic performance of bridges with BRBs. Taking the Dadu River Bridge as a case study, an FEA model of the bridge is established, and different seismic measures (BRBs between the deck and the tower, BRBs at the middle of the span to replace the inclined suspenders to connect the deck and the main cables, fluid viscous dampers (FVDs) between the deck and the tower, the combination of BRBs to replace the inclined suspenders as well as FVDs between the deck and the tower) are applied to the suspension bridge. The influence of the parameters of BRBs on the seismic response of the suspension bridge is studied, and the performance of the bridge with BRBs is compared with that of the bridge with FVDs. The results indicate that the use of BRBs in place of the inclined suspenders is beneficial to reduce the displacement of the deck and limit the shear force and bending moment of the tower. The seismic performance of the suspension bridge with BRBs and FVDs is better than that of the bridge with BRBs or FVDs. Therefore, the application of BRBs is a feasible method to improve the seismic performance of the suspension bridge.
  PubDate: 2022-02-04
Probability-based analytical model for predicting the post-earthquake
residual deformation of SDOF systems
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  Abstract: Abstract A probability-based analytical model for predicting the seismic residual deformation of bilinear single-degree-of-freedom (SDOF) systems with a kinematic/Takeda hysteretic model is proposed based on a statistical analysis of the nonlinear time history response, and the proposed model explicitly incorporates the influence of record-to-record variability. In addition, the influence of primary parameters such as the natural vibration period, relative yield force coefficient, stiffness ratio and peak ground acceleration (PGA) on the seismic residual/maximum deformation ratio (dR/dm) are investigated. The results show that significant dispersion of the dR/dm ratio is observed for SDOF systems under different seismic ground motion records, and the dispersion degree is influenced by the model parameters and record-to-record variability. The statistical distribution of the dR/dm results of SDOF systems can be described by a lognormal distribution. Finally, a case study for seismic residual deformation and reparability assessment of the bridge structure designed with a single pier is carried out to illustrate the detailed analytical procedure of the probability-based analytical model proposed in this study.
  PubDate: 2022-02-04
Response prediction using the PC-NARX model for SDOF systems with
degradation and parametric uncertainties
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  Abstract: Abstract Building collapses during recent earthquakes have brought up the need for research on factors pertaining to collapse and the safety of structures. This requires response replication of structures that account for uncertainties from ground motions and structural properties. Structural collapse often implies that the structural system is no longer capable of maintaining its gravity load-carrying capacity, which often points to factors involving strength and stiffness degradation. In this study, the polynomial chaos nonlinear autoregressive with exogenous input form (PC-NARX) model is explored for dynamic response replication of a nonlinear single-degree-of-freedom (SDOF) structure. The generalized hysteretic Bouc-Wen model is applied to emulate stiffness and strength degradation for an SDOF structure close to collapse. A stochastic ground motion model is used to represent the uncertainties in seismic excitation. The PC-NARX model is employed and further evaluated for response replication of an SDOF system with inherent uncertain structural properties. A generic algorithm (GA) is used to select the terms for structural dynamics, and polynomial chaos expansion (PCE) is used to incorporate uncertain parameters into NARX model coefficients. It is demonstrated that the PC-NARX model provides good accuracy to account for both ground motion and structural uncertainties into response replication of SDOF structures with significant strength and stiffness degradation. The PC-NARX model thus presents a promising technique for collapse safety analysis of structures.
  PubDate: 2022-02-04
Analytical evaluation and experimental validation on dynamic rocking
behavior for shallow foundation considering structural response
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  Abstract: Abstract The challenge in the practical application of rocking foundations is the estimation of its performance, particularly the rotation angle, during a strong earthquake. In this study, the dynamic rocking behavior for a shallow foundation considering structural response was evaluated through two analytical approaches: the conventional soil-foundation-structure interaction (SFSI) governing equation of a single-degree-of-freedom (SDOF) structure on a rocking shallow foundation, and the Housner rocking model (i.e., a rocking rigid block on a rigid base). Both approaches were validated with dynamic centrifuge tests. The test models consisted of a soft soil deposit, a shallow rectangular foundation, and an SDOF structure dominated by a bending behavior. A total of 11 foundation-structure systems and six seismic waves, including recorded earthquake signals and sinusoidal waves, were utilized. The results showed that the conventional SFSI equation well predicted the maximum rotation during strong earthquakes. However, this method was less accurate regarding the rotational phase information and maximum rotation of the foundation during weak earthquakes. On the other hand, although the modified Housner’s rocking model required five parameters relevant to a soil-foundation-structure system, it overestimated the maximum rotation of the foundation when compared with the results from dynamic centrifuge tests.
  PubDate: 2022-01-01
Discussion on blasting vibration monitoring for rock damage control in
rock slope excavation
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  Abstract: Abstract Drill and blast is a commonly used method for rock slope excavation in hydropower engineering. During blasting excavation of rock slopes, far-field vibration monitoring on the first upper berm for statutory compliance is usually performed to control the blast-induced rock damage to the final slope face. In this study, for the rock slope excavation in the Jinping-I hydropower station, the field vibration monitoring and acoustic testing are presented to investigate the vibration characteristics on the first upper berm and the damage depth in the current bench. The relationship between the PPV on the first upper berm and the PPV damage threshold on the damage zone boundary is also studied through three-dimensional FEM simulations. The results show that on the first upper berm, the maximum vibration velocity component occurs in the vertical direction. While on the blasting damage zone boundary, the horizontal radial vibration velocity is the maximum component. For the Jinping-I slope with a bench height of 30 m, the radial PPV on the inner side of the first upper berm is 2.06% of the PPV threshold on the damage zone boundary. This ratio is increased as the bench height decreases. Therefore, the bench height of the rock slope is an important factor that cannot be ignored in determining the allowable vibration velocity for rock damage control.
  PubDate: 2022-01-01