Search

Indonesia is a tropical country threatened by many disasters, such as earthquakes and other collateral hazards (liquefaction). Utilization of micro pile on the liquefaction prone areas is quite popular to increase the soil bearing capacity. In this research, Eucalyptus Pellita Timber was used as micro-piles alternatives. This study aims to determine the effect of timber pile addition on soil settlement and the increase in bearing capacity. Some laboratory investigations were conducted, such as timber and soil physical and mechanical characteristics, preloading tests, and seismic load tests by using small-scale shaking table test. The preloading tests were carried out for 40 days, and the settlements were recorded every 24 hours. Subsequently, seismic load tests were conducted on sandy soil with Dr = 40%. The seismic duration was 37 seconds, with PGA = 0.3 g and f = 0.78 Hz. The preloading test results show that Eucalyptus pellita timber piles are able to reduce the settlement by 18%. and from seismic load testing results are able to reduce the settlement by 68% due to earthquake loads with PGA = 0.3g and a frequency of 0.78 Hz on sandy soil with the potential for liquefaction. This is due to the resistance at the tip of the pile and the skin friction on the timber pile. So, from the results of the model test, it shows that the use of Eucalyptus Pelita timber piles can be used as an alternative to handling sandy soils in areas where liquefaction has the potential to occur. [ABSTRACT FROM AUTHOR]

Tunnels may suffer severe damage when passing through an active fault in high-intensity earthquake zones. The present study aims to investigate the performance of an isolation layer composed of a rubber-sand mixture, an emerging trend in low-cost seismic mitigation studies. Based on the Ngong tunnel in the Nairobi-Malaba Railroad in Kenya, Africa, the effect of the rubber-sand isolation layer on the acceleration and strain of the tunnel lining was investigated through a shaking table test under small normal fault creep-slip and subsequent seismic shaking. The influences of the length of the isolation layer and the rubber content in the mixture were analyzed by numerical simulation. The results indicate that the isolation layer slightly reduces the acceleration response of the tunnel lining within the fault and obviously reduces the permanent strain of the invert and crown within the fault under small normal fault creep-slip and subsequent seismic excitation. The mitigation effect of the isolation layer is related to the length of the isolation layer and the rubber content in the mixture. In the case of this study, the length of the isolation layer is triple the fault width (influence range of the fault) and the appropriate enhancement of the rubber content of the isolation layer offers favorable conditions for mitigation effect, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In seismic methods, pore pressure is estimated by converting seismic velocity into pore pressure and calibrating it with pressure results during the well-testing program. This study has been carried out using post-stack seismic data and sonic and density log data of 6 wells in one of the fields in SW Iran. While an optimum number of attributes is selected, the general regression (GRNN) provides higher accuracy than back propagation (BPNN) at the initial prediction stages. However, acoustic impedance (AI) is the most applicable seismic attribute used as root and reverses AI for estimating P-wave and density. Using a set of attributes can train the system to estimate the property. The correlation coefficient of actual and predicted P-wave using an AI seismic attribute has been calculated as 0.74 and the multi-attribute technique as 0.79. Also, density and three attributes reach from 0.57 to 0.60, which shows a better relationship between seismic attributes and density. After determining optimum layers with the principal component analysis (PCA), formation pressure was modeled with the feed forward–back propagation (FFBP-ANN) method. Five information layers, including gamma, VP, AI, density, and overburden pressure, have the most linear convergence with the initial pressure model and are used to modify the ANN model of effective pressure. [ABSTRACT FROM AUTHOR]

In the present study, the seismic performances of gravity retaining walls having both inclined back side and inclined backfill were investigated under sinusoidal acceleration excitations using series of shaking table tests on 750 mm height physical model. The effects of input peak ground acceleration (PGA$PGA$), inclination angle of backfill material (α) and inclination angle of back of the gravity retaining wall (β) on acceleration amplification factor (RMSA$RMSA$), maximum peak lateral relative (Smaxpeak(rel)${S}_{{\rm{maxpeak}}({rel})}$) and maximum residual lateral displacement (Smax(res)${S}_{{\rm{max}}({res})}$) of the wall, surface settlement (Sset${S}_{set}$) of the backfill material, inertial force (PI${P}_I$) and horizontal dynamic active force (Pdynh${P}_{dynh}$) were assessed. It was observed that higher values of the RMSA$RMSA$ were obtained from the experimental results as compared the ones from current seismic design codes. Moreover, the six results of shaking table tests revealed that the phase difference was appeared between the inertial force and dynamic earth pressures. Pseudo‐static limit equilibrium methods resulted in over conservative Pdynh${P}_{dynh}$ results and could not truly reflect the seismic behavior of gravity wall due to the inertial forces and phase difference not taken into consideration. [ABSTRACT FROM AUTHOR]

Probabilistic seismic hazard analysis (PSHA) is widely employed worldwide as the rational way to quantify the uncertainty associated to earthquake occurrence and effects. When PSHA is carried out for a whole country, its results are typically expressed in the form of maps of ground motion intensities that all have the same exceedance return period. Classical PSHA relies on data that continuously increase due to instrumental seismic monitoring, and on models that continuously evolve with the knowledge on each of its many aspects. Therefore, it can happen that different, equally legitimate, hazard maps for the same region can show apparently irreconcilable differences, sparking public debate. This situation is currently ongoing in Italy, where the process of governmental enforcement of a new hazard map is delayed. The discussion is complicated by the fact that the events of interest to hazard assessment are intentionally rare at any of the sites the maps refer to, thus impeding empirical validation at any specific site. The presented study, pursuing a regional approach instead, overcoming the issues of site specific PSHA validation, evaluated three different authoritative PSHA studies for Italy. Formal tests were performed directly testing the output of PSHA, that is probabilistic predictions, against the observed ground shaking exceedance frequencies, obtained from about fifty years of continuous monitoring of seismic activities across the country. The bulk of analyses reveals that, apparently alternative hazard maps are, in fact, hardly distinguishable in the light of observations. [ABSTRACT FROM AUTHOR]

The severe damage of conventionally designed buildings and consequent socioeconomic impacts after major seismic events have spurred the development of self‐centering systems with high seismic resilience. Post‐tensioned (PT) walls with rocking interfaces allowed to open and close and unbonded PT bars that provide most of the re‐centering ability have been developed extensively as a promising self‐centering technology. Aiming at providing essential insights into the seismic performance of self‐centering tube systems, a 1/6‐scale ten‐story self‐centering tube building was designed, constructed, and tested on a shaking table subjected to a series of unidirectional and bidirectional ground motions with increasing intensities. The test building consisted of a self‐centering tube that included four PT walls and provided the primary lateral force resistance in both directions, a perimeter rocking frame that was designed mainly to carry gravity loads, and particular connections with slots to accommodate the potential displacement incompatibility among the PT walls and surrounding components. The experimental results indicated the excellent seismic performance of the test building that had reliable structural integrity and experienced only confined damage even when subjected to extremely high intensities. The building also exhibited satisfactory re‐centering ability with minimal residual deformations at the conclusion of testing. It was demonstrated that the self‐centering tube system is a desirable low‐damage alternative to traditional tube systems in earthquake‐prone regions. The benchmark data from this test provided unique suggestions and support for further research on the design methods, numerical modeling, and experimental testing of self‐centering tube systems. [ABSTRACT FROM AUTHOR]

Beam–column connections (joints) are one of the most critical elements which govern the overall seismic behavior of reinforced concrete (RC) structures. Especially in buildings designed according to previous generation codes, joints are often encountered with insufficient transverse reinforcement detailing, or even with no stirrups, leading to brittle failure. Therefore, externally bonded composite materials may be applied, due to the ease of application, low specific weight and corrosion-free properties. The present work assesses the seismic performance of insufficiently reinforced large-scale T beam–column connections with large and heavily reinforced beams. The joints receive externally bonded NSM X-shaped composite ropes with improved versatile continuous detailing. The columns are subjected to low normalized axial load, while the free end of the beam is subjected to transverse displacement reversals. Different failure criteria are investigated, based on the beam free-end transverse load, as well as on the joint region shear deformations, to critically assess the structural performance of the subsystem. The experimental investigation concludes that cyclic loading has a detrimental effect on the performance of the joint. Absence of an internal steel stirrup leads to earlier deterioration of the joint. The unstrengthened specimens disintegrate at 2% drift, which corresponds to 34 mm beam-end displacement, and shear deformation of the joint equal to 30 × 10−4 rad. The composite strengthening, increases the structural performance of the joint up to 4% drift which corresponds to 68 mm of beam-end displacement and shear deformation of the joint equal to 10 × 10−4 rad. The investigated cases of inadequate existing transverse reinforcement in the joint and light external FRP strengthening provide a unique insight into the required retrofits to achieve different levels of post-yielding displacement ductility under seismic loading at 2%, 3% and 4% drift. It allows for future analytical refinements toward reliable redesign analytical models. [ABSTRACT FROM AUTHOR]

Seismic resilience is of paramount importance for the design and construction of structures in earthquake-prone regions. This study aims to provide a comprehensive analysis of the seismic performance of steel-concrete composite and Reinforced Cement Concrete (RCC) structures under dynamic loading, facilitating a comparative assessment of their respective behaviors. The behavior of cement-concrete composite structures, emphasizing the interactions between steel and concrete components, their energy dissipation mechanisms, and their contributions to seismic resistance are explored. This review contributes to the advancement of seismic design guidelines, aiding architects, engineers, and policymakers in making informed decisions regarding safer and more resilient structures. [ABSTRACT FROM AUTHOR]

The longitudinal direction of shield tunnels is prone to seismic damage due to excessive deformation under seismic action, especially in nonuniform stratum. In this paper, the longitudinal dynamic response of the tunnel under different seismic effects is calculated based on the longitudinal equivalent stiffness model using the stratigraphic load model, and the seismic indexes such as longitudinal corner, tube sheet and joint bolt stresses are verified. The calculation results show that the longitudinal seismic weakness of the shield tunnel is in the interface between soft and hard strata and karst development. The longitudinal axial force of the structure is larger during the longitudinal excitation of seismic waves, and the maximum bending moment is mainly in the vertical plane, i.e., the vertical bending moment. The axial force of the tunnel is smaller during the transverse excitation of seismic waves. The maximum bending moment is mainly the bending moment in the horizontal plane, i.e., the transverse moment. The South Lake section of the Two Lakes Tunnel has good seismic performance in the event of a rare earthquake with a 50-year exceedance probability of 2%. The investigation can guide the seismic design of the South Lake section of the Two Lakes Tunnel. [ABSTRACT FROM AUTHOR]

Fractured reservoirs are highly heterogeneous in both matrix and fracture properties, which results in significant variations in well production. Assessing and quantifying the influence of fractures on fluid flow is essential for developing unconventional reservoirs. The complicated effects of fractures in unconventional fractured reservoirs on fluid flow highly depend on fracture geometry, fracture distribution, and fracture properties, which can be reflected in pressure transient testing. The biggest challenge lies in delineating the pre-existing natural fracture distribution pattern, density, azimuth, and connectivity. Using the advanced finite element method, this paper builds a finely characterized near-wellbore model to numerically simulate the pressure transient testing process in naturally fractured reservoirs and further evaluates fracture-related effects to obtain a more accurate solution. First, the numerical program is benchmarked by the analytical solutions and numerical results of Eclipse. Next, different fracture models with single fractures or fracture networks are set up to investigate the effects of fracture parameters numerically (e.g., fracture location, fracture dip angle, fracture spacing, the ratio of fracture permeability to matrix permeability, fracture network orientation, horizontal fracture distribution, etc.) on pressure transient behaviors in naturally fractured reservoirs. Velocity and pressure profiles are presented to visualize and analyze their effects, and new features in the flow regimes of the derivative plots of the bottom-hole pressure are identified and discussed. Finally, based on geological and geophysical data, including image logs, core descriptions, wireline logs, and seismic and well test data, a practical fractured model of the Dalwogan 2 well in the Surat basin is built, analyzed, and compared with homogenous and measured data. The results show significance in characterizing the complex fracture networks in near-wellbore models of unconventional fractured reservoirs. [ABSTRACT FROM AUTHOR]

Tiny-fault detection plays a very important role in the research on the tight oil and gas reservoir in well area X in Ordos Basin, China. In this study, the target formation is the Majiagou dolomite reservoir section under the Ordovician salt with low-amplitude structures generally developed. The conventional attributes extracted from migrated seismic data could not achieve ideal results in detecting hidden faults with small displacement due to slight travel time differences and weak amplitude disturbances. To address this challenge, a segment and fusion strategy was adopted to highlight tiny faults in this region. First, the phase congruency analysis method was used to extract the local edges of coherence to locate the faults. Second, in the extraction process, the coherence was divided into segments according to the fault scales, and then enhanced segment by segment and fused. Third, the empirical formula of the new fault indicator was constructed by the phase congruency features, which can be used to accurately characterize tiny faults. This strategy performs well in both model tests and the migrated seismic data. [ABSTRACT FROM AUTHOR]

This paper presented an assembly scheme that was based on bundled bars–grouted corrugated duct connections. The scheme was used for the connection between the bridge column with bundled bars and the cap beam in an elevated subway station. Two 1/3-scale bridge column–cap beam joint specimens were designed and fabricated to verify the scheme. The test specimens included a precast assembly specimen and a cast-in-place (CIP) specimen. Pseudostatic cyclic loading tests were performed to investigate the flexural capacity, failure mode, and hysteretic behavior of the CIP and precast assembly specimens. The test results showed that: (1) the flexural capacity of the precast assembly specimen was close to that of the CIP specimen; (2) the energy dissipation capacity of the precast assembly specimen was weaker compared with that of the CIP specimen; and (3) the assembly scheme that was based on bundled bars–grouted corrugated duct connections was reliable. Finally, the finite-element model for the test specimens was established by calling the PQ-FIBER user subroutine developed by Tsinghua University with ABAQUS to study the seismic performance of the test specimens. Compared with the test results, the finite-element models could simulate the failure mode and hysteretic behavior of the reinforced-concrete specimens. [ABSTRACT FROM AUTHOR]

Collapsible soils are unsaturated low-density soils that undergo abrupt settlement when flooded without any increase in the in-situ stress level. The first stage of the site characterization is identifying collapsible soils, since these are problematic soils. Seismic cone testing (SCPT) has been increasingly used for site characterization, because it allows combining stratigraphic logging with the maximum shear modulus (G0) determination. In this paper, laboratory and in-situ tests carried out at 21 sites with collapsible and non-collapsible soils are interpreted to differentiate between such soils, based on the seismic cone test (SCPT). Collapsible soils have G0/qc values greater than 23 and qc1 values less than 70, while non-collapsible soils have G0/qc values less than 23 and qc1 values greater than 70. The investigated collapsible soils have microstructure (bonding/cementation), but the classical approach cannot be sufficient to identify collapsible soils alone. An approach was used to identify collapsible soils based on maximum shear modulus (G0), normalized cone resistance (qc1), and cone resistance (qc). The chart G0/qc versus qc1 and boundaries is an alternative for distinguishing between collapsible and non-collapsible soils in the early stage of site investigation. This qualitative approach should be used in the preliminary investigation phase to select potentially collapsible soils and helps guide the sampling of potentially collapsible soils for laboratory testing. Further SCPT data from different soil types, particularly the collapsible ones, are valuable to adjust or confirm the boundary equations suggested. [ABSTRACT FROM AUTHOR]

In this paper, the existing postearthquake performance assessment framework for reinforced concrete (RC) building structures is improved by adding a new feature of the computer vision‐based damage detection. In this framework, visible seismic damage is classified and quantified from photographs of damaged RC components using the developed deep convolutional network (CNN) Damage‐Net of semantic segmentation, and then the mechanical property degradation factors of components determined from the detected damage states are used to update the numerical model. Pushover analysis of the updated model assesses the residual capacity of the damaged structure. Large‐scale shaking table tests of a three‐story RC building structure, which was heavily instrumented with sensors and recorded with a large volume of photographs, were used as a case study to demonstrate the improved postearthquake performance assessment framework. The vision‐based approach accurately detected multicategory seismic damage of the test structure and effectively estimated the residual crack widths and angles under various lighting, image acquisition, and surface conditions. The updated model, which incorporated the mechanical property degradation of the damaged components, provided accurate estimate on the fundamental vibrational frequencies of the damaged structure after various levels of seismic motion shaking, which matched well with the system identification results. Using the mechanical property reduction factor values recommended by FEMA 306 & Chiu et al., pushover analysis of the updated models provided residual capacity curves that reasonably captured the measured hysteretic responses of the structure. In addition, the damage states of components as estimated by the vision‐based methods were also compared with the measured plastic hinge rotation data. The successful implementation of the vision‐based assessment in this test case indicates its potential for application in the postearthquake evaluation of buildings. [ABSTRACT FROM AUTHOR]

Copyright of CT Theory & Applications is the property of Editorial Department of CT Theory & Applications and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Crosshole seismic testing is commonly used to determine detailed and reliable wave velocity profiles. Material damping measurements can also be performed in crosshole seismic testing, but these measurements require a window function to maintain similar amplitude shapes over the frequency range of interest for the calculation. In-situ seismic testing, including downhole and seismic cone penetration testing (SCPT), also requires a window function for the material damping calculations. However, the length of the window function has the largest influence on the material damping calculation. Therefore, the half-power bandwidth method is introduced to determine the material damping ratio without the window function in crosshole testing by replicating the unconfined, free-free, resonant column (Fr-Fr) test. To demonstrate the influence in the length of the window function, the first cycle of the signal is used in the material damping calculation. The half- power bandwidth method is verified using synthetic signals and field data. Two sets of crosshole and downhole tests were performed, one at a backfill test pad and the second at a Hornsby Bend research site operated by the University of Texas at Austin. The in-situ material damping ratio calculated from these two sets of crosshole tests using the half-power bandwidth method are compare with the Spectral Ratio Slope (SRS) method applied to the downhole testing at these sites. The material damping calculated from the half-power bandwidth method using the full signal results in a reliable and precise damping value compared to the SRS method applied to the downhole data.

A numerical method based on the panel method was developed to calculate the added fluid mass coefficients of the rigid section group with arbitrarily complex shapes, and was successfully applied to the PWR fuel assemblies. The variation law of added mass coefficients with position deviations was analyzed in the seismic test of 1×5 fuel assemblies. The results show that, this method is suitable for the calculation of the added mass coefficients of rigid section groups with complex continuous boundaries. Compared with the gap between assemblies, the gap between baffles and assemblies has a dominant influence on the added mass coefficient. Regardless of the position deviation, the sum of the added mass coefficients of all assemblies and baffles in the assumed motion direction is approximately equal to –1, and that in the perpendicular direction is approximately equal to 0. [ABSTRACT FROM AUTHOR]

This paper introduces a news processing method for geomagnetic anomaly field data: envelope mode magnetic field, which can weaken the influence caused by geomagnetic polarity reversal during rock magnetization, reflect the magnetic change of crustal rocks, and locate the crustal structures. According to the characteristics of the magnetic anomaly field, the envelope mode magnetic field is calculated in three different ways: full anomaly envelope, positive anomaly envelope, and negative anomaly envelope. The simulation test of seismic signal and magnetic anomaly model has achieved good results. During the calculation of the real-world data, because the magnetization directions of the geomagnetic field in the southern and northern hemispheres are opposite, we use the full envelope or positive envelope method for the northern hemisphere and the negative envelope method for the southern hemisphere. The experiment using EMAG2 global satellite magnetic anomaly data demonstrates that the strong anomaly of the envelope mode magnetic field is consistent with the spatial distribution of cratonic tectonic units, confirming its application effect. [ABSTRACT FROM AUTHOR]

Prestack seismic inversion has been widely used around the seismic exploration. It can precisely output the elastic properties of layers in subsurface, e.g., P-wave velocity ( V p ), S-wave velocity ( V s ), and density (ρ ). These are utilized further to extract many reservoir properties, like saturation and porosity, which are very helpful for the successful oil field development. The accuracy of prestack inversion result could play a critical role for the evaluation of reservoir characterization and the quantitative interpretation. It has been observed the existing relationships among velocities and density ( V p , V s , and ρ ) lead to the correlations of three reflectivities ( R p , R s , and R ρ ). In this paper, we establish a new formulation for amplitude-versus-angle (AVA) inversion incorporating these correlations. A machine learning technique—block sparse Bayesian learning, has been implemented as the inversion engine to solve R p , R s , and R ρ and to estimate the correlations described as the covariance matrix automatically. Due to the contribution of relationship between velocities and density, the performance of proposed AVA inversion is superior to the conventional technique in denoising and highlighting small-scale reflections. Three reflectivities are finally converted into velocities and density via an optimal multi-trace algorithm L-BFGS, which can mighty mitigate the lateral discontinuity of inverted results. The proposed approach has been tested on the synthetic examples. It shows a good consistence between inverted and true elastic properties. Field data test with the seismic profiles in Ordos basin area has demonstrated its high feasibility and efficiency for practical applications. [ABSTRACT FROM AUTHOR]

Designing frame structures requires knowing the behaviour of each member of the frame (beam, column, joint, etc.) regarding the axial forces, shear forces, and bending moments. Furthermore, the ductility of the structure under seismic loading is essential in earthquake regions. Nowadays, structural frames are built from different materials such as concrete and steel, to achieve better performance. Therefore, the behaviour of the connections between steel and concrete is essential. The steel‐to‐concrete joints were the focus of the INFASO project, where joint solutions with easy fabrication, quick assembly, applicability in old structures, sufficient ductility, and high loading capacity were developed. They proposed the use of anchor plates with welded studs or post‐installed fasteners such as adhesive anchors to connect the steel and concrete members. This paper focuses on the performance of post‐installed adhesive anchors. During their service life, post‐installed anchors are subjected to monotonic, constant, and seismic loading. Each of these loading approaches is described in the current standards. Seismic and constant loading tests are of importance to the long‐term behaviour of the anchors. Seismic loading tests are carried out using a predefined cycle pattern. According to TR049, seismic tests of category C1 (tension and shear) are performed with 140 load cycles, where the load amplitude decreases after 10, 30, and 100 cycles. On the contrary, C2 category tests increase the amplitude within 75 or 59 cycles, depending on the test. Constant loading tests apply when the anchors are installed in cracked concrete. In contrast to the mentioned patterns, this study observes the behaviour of the adhesive anchors when the amplitude of each cycle is increased by 5 % until the anchor fails. Standard short‐term pull‐out tests are carried out to determine the load increments. Various parameters such as the embedment depth, bond line thickness, hole cleaning, wet concrete, and elevated temperatures are studied. Confined and unconfined tests are performed. Overall, the reference short‐term failure loads are higher than those in the tests with incremental and cyclic loading. The anchors installed with reduced hole cleaning, in wet concrete or subjected to elevated temperatures have a lower failure load compared to the reference series. Two additional bond line thicknesses are used for comparison. The increase in the thickness influenced the failure load differently for confined and unconfined test setups. [ABSTRACT FROM AUTHOR]

In recent years, many large‐scale liquefied natural gas (LNG) storage tanks have been built all over the world. Due to their high constructional cost and important functions to the public, the academic and engineering communities are very concerned with the operational safety of these important infrastructures once subjected to potentially disastrous actions, that is, earthquakes, typhoons, tsunamis, and so forth. This work presented a benchmark test in evaluating the aseismic performance of extra‐large prestressed reinforced concrete (RC) LNG storage tanks. A 1:14 scaled model of the prototype LNG tank was designed and constructed for shaking table tests. Two recorded and two artificial earthquake ground motions with peak ground acceleration (PGA) up to 1.2g were selected successively as seismic inputs to the tank. The acceleration, displacement, shear force, and strain responses of the model structure were presented, analyzed, and discussed in detail. It was found that due to the differences in the frequency spectra, the seismic excitations have distinct influences on the responses of the tank model. In particular, the wall‐roof junction was detected as the weakest part of the outer tank, and the filling water had non‐negligible effects on the overall seismic responses of the tank. Verified finite element simulations were also presented as supplements to the experimental study. Some suggestions were made with the aim to improve the designs of LNG storage tanks. [ABSTRACT FROM AUTHOR]

The vibration generated by underground trains and the level of vibration attenuated along the propagation path are the keys to designing mitigation measures to avoid adverse effects on the surroundings. The attenuation of vibrational energy due to geometrical and material damping was determined at the Civil Court Godown, Pune Metro, Maharashtra, India, up to 30 m. The seismic cross-hole test was used to determine the dynamic properties of the soil. It was found that the soil stratum was homogeneous and composed of basaltic rock. The total vibration level reaching the receiver was predicted for trains travelling at 80, 250 and 350 km/h, and vibration attenuation measures such as steel mass-spring systems and polyurethane mass-spring systems have been proposed. [ABSTRACT FROM AUTHOR]

There are currently at least five aircraft runways built on the reclaimed coral sand foundations in the South China Sea (SCS). The seismic dynamics and stability of the revetment breakwaters and nearby aircraft runways built on reclaimed lands with coral sand in the SCS deserve attention. Taking the reclamation engineering in the SCS as the background, this study performed several centrifuge shaking table tests (N = 50 g) to explore the seismic dynamics and stability of a revetment breakwater and a nearby aircraft runway built on a reclaimed coral sand foundation. It is revealed that the revetment breakwater, aircraft runway, and their coral sand foundation have intensively responded to the excitation of seismic waves. The pore water pressure accumulates in the coral sand foundation; however, the accumulation amplitude is not significant. As a result, only soil softening, rather than liquefaction, has occurred in the coral sand foundation. The final residual subsidence of the revetment breakwater and aircraft runways are both about 0.5 mm, indicating that they are finally in a stable state. Through comparative study, it is found that the pore water pressure in the loose coral sand foundation is much easier to accumulate, and the corresponding acceleration amplification effect is also more significant. It means that a loose coral sand foundation is more detrimental to the seismic stability of the revetment breakwaters and airport runways. [ABSTRACT FROM AUTHOR]

Summary: A super tall building named Ningbo Hengda Tower is located in Ningbo City, China. It has 91 stories with a total height of 450 m. The structure system of the building consists of three parts, that is, the reinforced concrete core, the outer frame system, and the outrigger trusses connecting the core wall and outer frame. The unique outer frame system is spindle shaped with oblique columns. The outrigger trusses are located at three different levels above the ground, thus strengthening the building and creating irregularities in the stiffness of the structure along the building height. Great challenges are existed in seismic design and analysis of the building. Shaking table test was carried out for a 1/40 scaled model of the building under a series of different base excitations with increasing amplitudes. The dynamic properties, seismic responses, and failure mechanism of the structure are investigated. Test results show that the structure behaved well under designed level earthquakes. The weak points of the structure are identified based on visible damage of the tested model, and some suggestions are made for the improvement of the seismic behavior of the building. It is suggested that measures be taken to improve the ductility of the building from floor 71 to floor 79 and the adjacent floors. [ABSTRACT FROM AUTHOR]

It is difficult to accurately establish a model of the real mesa system. Furthermore, a model of a seismic simulation vibration table array system is critical to increasing the accuracy of seismic testing in laboratory settings. Herein a model of the nine subarray shaking table system is identified by recursive extension of the least square method, which is used to accurately identify the structure parameters by simulation of the structure assuming a single degree-of-freedom. Then, through the displacement of the empty shaking table and the application of the recursive least squares algorithm, the model of the seismic simulation vibration table array is established. Through this study, the vibration table model of different construction forms can be obtained, and the parameters that are difficult to measure for some complex structures can effectively be determined. [ABSTRACT FROM AUTHOR]

A series of centrifuge experiments were conducted to identify different internal failure modes of a group of soil-cement (SC) columns (e.g., shearing and tension due to bending) under combined effects of embankment loading and liquefaction-induced lateral spreading. The results were also used to investigate how an increase in the flexural/shear strength of SC columns (using high-strength steel reinforcement bars) can affect their ability to limit settlements or deformations. The centrifuge experiments included two centrifuge tests of liquefiable foundation reinforced by SC columns with and without high-strength steel reinforcement cores during strong earthquake loading. It was found that during and after cracking of the SC columns, shear and tilting failure is the prominent failure mechanism. The test results showed that increasing the flexural capacity of SC columns can reduce the potential for earthquake-induced liquefaction and associated damage. Compared with conventional SC columns, reinforced soil-cement (RSC) columns are more effective in providing confinement for the soil under the embankment during strong shaking events, resulting in lower shaking-induced pore-water pressure and a reduction in the lateral deformation of the soil and embankment. [ABSTRACT FROM AUTHOR]

Earthquakes are the most dangerous natural disasters, and scholars try to predict them to protect lives and property. Recently, a long-term statistical analysis based on a "heating core" filter was applied to explore thermal anomalies related to earthquakes; however, some gaps are still present. Specifically, (1) whether there are differences in thermal anomalies generated by earthquakes of different magnitudes has not yet been discussed; and (2) thermal anomalies in high-spatial-resolution data are often distributed in spots, which is not convenient for statistics of thermal anomalies. To address these issues, in this study, we applied high-spatial-resolution thermal infrared data to explore the performance of the "heating core" for earthquake prediction at different magnitudes (i.e., 3, 3.5, 4, 4.5, and 5). The specific steps were as follows: first, the resampling and moving-window methods were applied to reduce the spatial resolution of the dataset and extract the suspected thermal anomalies; second, the "heating core" filter was used to eliminate thermal noise unrelated to the seismic activity in order to identify potential thermal anomalies; third, the time–distance–magnitude (TDM) windows were used to establish the correspondence between earthquakes and thermal anomalies; finally, the new 3D error diagram (false discovery rate, false negative rate, and space–time correlation window) and the significance test method were applied to investigate the performance under each minimum magnitude with training data, and the robustness was validated using a test dataset. The results show that the following: (1) there is no obvious difference in the thermal anomalies produced by earthquakes of different magnitudes under the conditions of a "heating core", and (2) the best model with a "heating core" can predict earthquakes effectively within 200 km and within 20 days of thermal anomalies' appearance. The binary prediction model with a "heating core" based on thermal infrared anomalies can provide some reference for earthquake prediction. [ABSTRACT FROM AUTHOR]

Rammed earth construction is spread worldwide in new buildings and also as architectural heritage, representing a cultural identity that must be preserved. However, rammed earth heritage is also well known for its high seismic vulnerability and despite the increasing concern for this aspect, few experimental investigations were conducted so far on the seismic response of such structures due to the high required costs and complexity of the tests. Shake table tests are the most adequate to investigate the performance of a building; indeed, besides allowing direct observations, seismic tests consent to calibrate numerical models that can be later used to investigate the sensitivity of the structure to various parameters. In this framework, an experimental program was undertaken on a rammed earth mockup by means of shake table tests carried out at the National Laboratory of Civil Engineering (LNEC) in Lisbon. To investigate the out-of-plane behaviour of rammed earth walls, the mockup was built in full scale with a U-shape plan and then was subjected to a series of seismic inputs with increasing magnitude. The results are here discussed in terms of crack pattern, damage detection, peak displacements, base shear coefficient, hysteretic curve, and dissipated energy against ground motion parameters, such as peak ground values, cumulative absolute velocity (CAV), arias intensity (AI), input energy (IE), and specific energy density (SED). In conclusion, the model responded as a rigid block to earthquake simulations, and linear and quadratic correlations were found between the performance of the mockup and various of the seismic input parameters. [ABSTRACT FROM AUTHOR]

Ordinary braces upon experiencing compressive buckling, reach a fully plastic state, rendering them ineffective against further seismic action. Moreover, their post-earthquake repair and reinforcement pose significant challenges. Addressing these issues, this research introduces an innovative lateral force-resisting element: the bending energy dissipation-cable brace. This novel design utilizes steel cables in a unique tension-only arrangement, effectively dissipating seismic energy by inducing bending in a steel plate. A semi-rigid steel frame was constructed, incorporating two variations of the cable brace, differentiated by the thickness of their energy-dissipating frames. These were subjected to quasi-static cyclic loading tests to evaluate their hysteretic behavior, deformation pattern, load-bearing capacity decay, and energy dissipation capacity. The experimental results reveal the superior seismic performance of the bending energy dissipation-cable brace, evidenced by a 22 % enhancement in energy dissipation and a 38 % increase in stiffness when the thickness of the energy-dissipating frame is doubled. These results offer a promising solution to the current limitations in energy dissipation and difficulty of application of the combined brace of steel cable and bending yielding energy dissipation devices. • A novel cable brace, the bending energy dissipation-cable brace (BED-CB) was proposed. • Seismic test and analysis of the bending energy dissipation-cable braced semi-rigid steel frame are performed. • Hysteretic performance, stiffness, ductility, energy dissipation capacity are studied. • BED-CB is an effective lateral force-resisting component for semi-rigid steel frame at large displacements. [ABSTRACT FROM AUTHOR]

Austenitic stainless steel is recognized for its potential in improving structural seismic resistance due to its exceptional ductility. This study seeks to analyse the material characteristics and cyclic constitutive model of austenitic stainless steel under cyclic loading using a combination of experiments and numerical studies. The primary goal is to enhance the precision of numerical simulations predicting the seismic performance of stainless steel and to minimize the costs associated with calibrating the parameters of the cyclic constitutive model. By conducting cyclic loading experiments on stainless steel with different plate thicknesses, the hysteresis curves under different loading protocols were obtained. The loading protocol significantly influences the cyclic hardening behaviour of stainless steel. To calibrate material parameters in the Chaboche model more effectively, a new parameter calibration method based on genetic algorithm optimization is proposed. Additionally, a method is proposed to calibrate the material parameters of the Hu model by utilizing the monotonic tensile stress-strain curve of austenitic stainless steel, which provides a new material model option for the numerical simulation of stainless steel seismic performance. The applicability of the Chaboche model and the Hu model in numerical simulations of stainless steel members is then verified and compared using existing seismic performance test results. The findings indicate that the Hu model offers more accurate numerical simulations of cyclic loading on austenitic stainless steel members compared to the Chaboche model. • The material properties of stainless steel under seismic loading were investigated. • A parameter calibration method based on genetic algorithm optimization was proposed. • A method was proposed to calibrate the material parameters of the Hu model. • The applicability of the Chaboche and Hu models in numerical simulations was evaluated. [ABSTRACT FROM AUTHOR]

An hold-down device was designed and tested experimentally for seismic applications (Seismic Hold-Down, SHD). The magnitude of axial strength as well as the up-lift displacement capacity is mainly oriented to cross-laminated-timber (CLT) buildings with medium-to-high ductility. There is consensus in the design practice of hold-down devices for promoting, as dissipative mechanism, flexural yielding of the dowel-type connectors (e.g. nails, screws) combined to timber's embedment. Few are the applications aiming at hold-down's optimization as it emerges from up-to-date literature review. In this framework, SHD was conceived such that tension break-out of steel was promoted at a reduced segment (fuse) of the vertical flange. In the context of capacity design, a convenient overstrength was assumed for other failure mechanisms, e.g. anchor's pullout, laterally-loaded steel-to-timber connection, shear-plug of timber. The mechanical response under axial load was consistently predicted by an application of the component method, i.e. global stiffness and strength were analytically-derived using simplified series of non-linear mechanical springs. Three-dimensional finite elements model was employed to investigate buckling of the fuse which might occur, during cycles, when up-lift displacement is recovering. In practical circumstances, it is recommend to design SHD devices of a CLT wall similarly to diagonal elements of steel bracings, i.e. neglecting the contribution of the compressed element. Finally, SHD is compared to traditionally-designed hold-down, which mostly dissipates (and fails) at steel-to-timber connection. Overall hysteretic response is somehow similar, although the inelastic mechanisms involved are different. For example, both the devices show pinching during cycles which for SHD is mainly caused by buckling of the fuse while, for traditional hold-down, is dominated by timber's embedment. • Hold-Down connection designed for application on seismic-resistant CLT buildings. • Application of capacity design according to Second Generation Eurocodes. • Discussion on analytically-derived performance using component method. • Discussion on numerically-derived buckling. • Discussion on pinching of hysteretic behavior. [ABSTRACT FROM AUTHOR]

The seismic performance of Chuan-dou timber structures was investigated. A 1:2 scale model of a Chuan-dou timber structure was constructed, with the bottom part filled with masonry and the remaining portions filled with gypsum board. Through quasistatic tests, we compared and studied the impact of whether the column foot is constrained on the seismic performance of Chuan-dou timber structures. The results indicate that when the horizontal displacement of the column foot is restricted, the force distribution pattern of the timber frame changes, and the lateral resistance capacity increases by approximately two times. The lateral force‒displacement relationship of the timber frame exhibits two stages, where the load in the second stage does not decrease as the displacement increases. Additionally, a simplified finite element model incorporating mortise−tenon (M−T) joints and column foot connections reflects the hysteresis performance of the bare timber frame. A simplified wall model that considers the rocking effect can be used to simulate the lateral force‒displacement relationship of the timber frame. [ABSTRACT FROM AUTHOR]

This correction notice addresses an error in the article "Full-Scale Seismic Performance Testing of a Predamaged Two-Story Traditional Timber Frame on a Slope Reinforced Using Viscoelastic Dampers" by Duhang Yi, Jiacong Yuan, Yi Pan, and Yuanqing Fan. The correction involves the inclusion of the correct Figure 18(b) in the article. The authors apologize for any confusion caused by the incorrect figure and state that the correction has been made only in this erratum to preserve the published version of the record. [Extracted from the article]

This study developed a novel composite energy-dissipation prefabricated RC beam-column joint featuring a multi-level yielding mechanism, incorporating composite energy-dissipation boxes (EDBs) and friction side plates (FSPs). In order to investigate the synergy work performance between FSPs and metal EDBs, six specimens were fabricated, including series A and series B. The theoretical slip bending moment (M slide) of the FSPs was determined, followed by low-cycle reversed tests on the specimens to analyze failure modes, hysteresis performance, ductility coefficient and the prediction of load-carrying capacity. The results indicate that FSPs effectively prevent fractures in the dog bone-energy dissipation plates (DB-EDPs) of the EDBs, thereby enhancing ductility and energy dissipation capacity. Furthermore, a theoretical formula for the load-carrying capacity of the plastic joints was developed and experimentally validated, providing accurate predictions for load-carrying capacity in specimens with only EDBs. It is worth noting that the drift ratios at peak loads of the FSPs and EDBs varied among specimens, with an average theoretical to experimental value ratio of 1.20 for the three specimens (S-1-1 , S-2-1 , and S-3-1) analyzed. • This study presents a composite energy dissipating prefabricated RC beam-column joint with a multi-level yielding mechanism. • Based on theoretical formula derivation, the bearing capacity formula of the FSPs was proposed. • The FSPs are intentionally weakened to ensure that the DB-EDPs undergo metal yielding before the FSPs start rotating. • The EDBs consisted of dog bone-energy dissipation plates (DB-EDPs) with a large slenderness ratio. [ABSTRACT FROM AUTHOR]

The pile leg-mat foundation is a novel composite foundation designed for jack-up offshore platforms. The seismic response of such foundations in sandy seabeds is an issue that requires significant attention. In this study, shaking table tests were conducted under various input seismic waves to investigate the dynamic response of a seabed platform system subjected to seismic loads. The effects of the peak ground acceleration (PGA), seismic wave frequency, wave type, pile leg insertion depth, and pile length on the response of the seabed platform system were investigated. The results indicated that as the PGA increased, the acceleration response of the soil and platform model increased, increasing the accumulation of excess pore water pressure and the horizontal displacement of the platform model. The acceleration and horizontal displacement responses of the seismic wave with lower frequencies were higher than those with higher frequencies. The peak acceleration amplification factors under the measured and regular seismic waves showed significant differences, with the dynamic response of regular waves to the platform model being pronounced. Under seismic waves with low PGAs, the horizontal displacement of the platform model decreased with increasing pile leg insertion depth or pile length. • Shaking table tests for jack-up platform with pile leg-mat foundation on sandy seabed were conducted under various seismic wave conditions. • The seismic response such as acceleration, excess pore water pressure, and displacement of the seabed-platform system were revealed. • The effects of the seismic waves, pile leg insertion depth, and pile length on the seismic response of the seabed-platform system were investigated. [ABSTRACT FROM AUTHOR]

Four precast concrete composite walls with embedded extruded polystyrene insulation layer were designed, and the seismic performance was systematically investigated. The failure mode, hysteretic curve, skeleton curve, stiffness degradation, displacement ductility and energy dissipation capacity were explored by quasi-static tests. Moreover, the strain variation of reinforcements at the key positions of the specimens was analyzed and discussed. The test results indicated that the failure mode of the specimen with extruded polystyrene insulation layer thickness of 200 mm was flexural failure, accompanied by the concrete crushing and spalling at the wall toes; while the specimen with extruded polystyrene insulation layer thickness of 100 and 120 mm showed better cooperative working performance. The precast composite concrete wall adding diagonal braces possessed better bearing capacity, deformation capacity and cumulative energy dissipation capacity. Furthermore, the connecting reinforcements at the horizontal joint can effectively transfer stress. Finally, a simplified calculation model of bearing capacity of the precast concrete composite walls with embedded extruded polystyrene insulation layer connected by tooth groove and grouted sleeve was proposed. • An innovative precast concrete composite wall with embedded XPS insulation layer was proposed. • An innovative tooth groove and grouted sleeve connection method was proposed. • The seismic performance of precast concrete composite wall was investigated by quasi-static test. • A simplified calculation model of bearing capacity of precast concrete composite wall was established. [ABSTRACT FROM AUTHOR]

Seismic hazard maps are crucial for earthquake mitigation and mostly rely on probabilistic seismic hazard analysis (PSHA). However, the practise and value of PSHA are under debate because objective testing procedures for seismic hazard maps are scarce. We present a lacustrine turbidite record revealing 44 earthquakes over the last ~ 14 ka and use it to test seismic hazard curves in southern Austria. We derive local seismic intensities for paleo-earthquakes by applying scaling relationships between the sedimentary imprint and seismic intensity of well-documented historical earthquakes. The last ~ 2.8 ka of the record agree with a Poissonian recurrence behaviour and therefore a constant hazard rate, which is the modelling choice for standard PSHA. The lacustrine data are consistent with the intensity-frequency relationship of the local seismic hazard curve, confirming the current PSHA approach for this part of Austria. On longer timescales, distinct phases of enhanced regional seismicity occurred, indicating a potential increase of seismic hazard after large earthquakes—a factor hitherto disregarded in the PSHA of the Eastern Alps. Our new method forms an independent procedure to test hazard maps in any setting where suitable lake systems are available. [ABSTRACT FROM AUTHOR]

The anti-seismic problem of rural residential buildings is the weak link of seismic retrofitting in China. Recently, geotechnical seismic isolation (GSI) technology based on rubber–sand mixtures (GSI–RSM) using rubber–sand mixtures (RSM) between the structural foundation and the foundation soil has been proven to have the possibility of potential applications in rural residential buildings. Many theoretical studies exist on the effectiveness of seismic isolation of the GSI–RSM system, but few studies on either the seismic response test of model buildings placed on the RSM layer or the large-scale shaking table test exist. Therefore, this study considers a large shaking table test performed on a 1/4 single-story masonry structure model with and without a GSI–RSM system by selecting a standard input ground motion and varying input acceleration amplitudes. The test results show that the GSI–RSM system can reduce the seismic response of superstructures. The isolation effect of the GSI–RSM system is low in small earthquakes and increases with increasing earthquake magnitude. Overall, the RSM layer can filter part of the high-frequency components of the earthquake to transmit to the superstructure and consume more seismic energy by generating friction slip in the interaction with the structural foundation. [ABSTRACT FROM AUTHOR]

Slope failures in roadway embankments are common occurrences and can lead to traffic disruptions and large costs to repair damage. In areas with high-plasticity clays, special attention must be paid to characterizing both the stratigraphy and the potential for strength loss. This study demonstrates the use of an integrated site characterization approach, which seeks to utilize results from geotechnical and geophysical tests to understand the behavior of a landslide in west Alabama. The timing and mechanism of the initial failure causing the preexisting shear plane at this site are not known. Results from electrical resistivity and seismic geophysical tests are integrated with information from borings and index tests to develop a representative cross-section for the landslide, and torsional ring shear results are used to measure the drained fully softened and residual strengths. Both the limit equilibrium (LEM) and strength reduction method (SRM) analyses are used to examine possible failure mechanisms. The results show good agreement between noncircular LEM and SRM analyses and indicate that the initial failure was likely due to undrained loading of the clay. Analyses utilizing the residual drained strength envelopes produce FS values significantly lower than 1 indicating the slope to be unstable when soil on the failure plane exists at the residual state. Sensitivity analyses suggest that the combined effect of lowering the water table and strength recovery may explain the intermittent nature of movements. [ABSTRACT FROM AUTHOR]

The intention of this study is to estimate the expected soil-building resonance phenomena of the Dhaka Metropolitan Development Plan (DMDP) area of Bangladesh during earthquakes. The target is to identify the effect of the geology of the shallow depth and the buildings situated on the ground above the DMDP area. The predominant frequency of the soil is obtained from the horizontal-to-vertical spectral ratio (HVR) analysis of microtremor observations. Similarly, longitudinal and crosswise principal vibrational frequencies of each building have been ascertained from the fast Fourier transform (FFT) of the observed microtremor measurements. When the principal vibrational period of the structure is near to the period of the nearby ground, building-soil resonance may occur. A rapid visual assessment (RVA) has been carried out for 3,252 educational institutes in the DMDP area and through the prioritization scheme, 611 buildings have been selected for preliminary engineering assessment (PEA). Some of these buildings will be later allowed to be either retrofitted or demolished based on the findings of this study. Out of those prioritized buildings, microtremor measurements have been performed on selected 114 buildings and nearby soil for which standard penetration test and seismic downhole test data are available. Also, microtremor observations at additional 500 free-field locations are available from a previous study. The period-number of story linear relationship, estimated from the 114 microtremor observations, allowed estimating the fundamental frequency for 3,252 buildings. The DMDP area symbolizes a significant example since the principal vibrational period for the majority of the structures is reasonably different from the predominant period of the nearby ground. Only around 4% of the structures demonstrate a significant likelihood that a building-soil resonance effect may take place, while around 96% are at a relatively low resonance stage. [ABSTRACT FROM AUTHOR]

A path for testing a probabilistic seismic hazard assessment (PSHA) map is presented in this paper via the evaluation of fortification benefit with two indices, economic benefit and safety benefit. The effect of fortification intensity on the vulnerability of the engineering structure is emphasized in the damage estimation of the evaluation. The expected losses and casualties are calculated based on the total areas in each of the five damage states with local parameters. The result of a case study of the 1990 PSHA map of China shows that the expected total reduction of loss from the damage to brick concrete and reinforced concrete buildings constructed during the in-service period of the map and damaged in the subsequent destructive earthquakes is RMB 216.5 billion. Thus the expected economic benefit is RMB 17.5 billion in comparison to the additional fortification cost of RMB 199.0 billion. The expected casualty reductions are 20,838 fewer deaths and 77,801 fewer serious injuries. This indicates that the implementation of the 1990 PSHA map has indeed played a beneficial role in earthquake disaster mitigation. The evaluation result of the marginal benefit of fortification, in terms of increasing or decreasing the fortification intensities by one degree further for the whole country, shows that the fortification level adopted in China is appropriate as a whole. [ABSTRACT FROM AUTHOR]

Recent editions of Canadian national building codes increased the height limit for wood-frame construction from four to six stories. In addition, the seismic loads have also been increased. These increases in building height and seismic loads have raised the demand for a stronger shear wall system for construction of midrise wood-frame buildings, especially for those located in high seismic zones. In collaboration with FPInnovations, a new high-capacity shear wall system with multiple rows of fasteners along sheathing edges was developed. This paper presents the test results of shear walls with two rows of nails. A total of 10 specimens were tested under cyclic loading. Test results show that shear walls with two rows of nails have 1.8–2.0 times the lateral load resistance of a standard shear wall with the same sheathing thickness, nail diameter, and nail spacing. The initial stiffness and ultimate displacement of the high-capacity shear wall are also greater than that of the comparable standard shear wall. Based on seismic equivalency criteria, shear walls with two rows of nails can be assigned a design value of the comparable standard shear wall multiplied by a factor of 1.7. [ABSTRACT FROM AUTHOR]

In recent decades, connections between concrete-filled steel tubular columns (CFST) and H-steel beams have been well designed and implemented. However, owing to the detail of the weld, brittle failure often occurs at weld seams. In this study, an innovative joint was developed to connect CFST columns and H-steel beams using a top-weld bottom-bolt connection to minimize the effect of welding quality on the seismic resistance of joints. Six specimens were designed for cycle-reversed loading tests to discuss the seismic performance of this joint. Four configurations, including different connection methods, beam heights, column forms, and stiffener thicknesses, were considered in the test. The impacts of different configuration forms on the failure mode, strength, stiffness, ductility, and energy dissipation of the specimens were evaluated. The test results demonstrated that the columns with or without concrete had a significant effect on the deformation capacity. However, a smaller effect was observed on other indicators. The replacement of the through-diaphragm and an increase in the beam height adversely influenced the ductility of the joint. Moreover, changing the stiffener thickness and using a full-bolted connection affected the failure mode. The joint type analyzed in this study satisfies the strong column–weak beam design criterion and the related seismic provisions. [ABSTRACT FROM AUTHOR]

The performance of batter-piled raft systems during seismic events continues to be a major concern. In response, a series of shaking table tests, including vertical and nonvertical configurations, were conducted, and the effects of superstructure frequency and pile angle on the seismic performance of the models were examined under a wide range of accelerations (0.2–0.7 g). Smaller bending moments, horizontal displacements, and rotations were captured for the nonvertical models, so the application of batter piles is reliable under seismic conditions. The maximum bending moment in the vertical models was recorded to be 8 times greater than in the batter piles at the lowest level of ground motion. Thus, the performance of the system was more sensitive to the frequency of the superstructure for vertical piles. [ABSTRACT FROM AUTHOR]

In this study, seven one-third-scale bridge column specimens are tested via a quasi-static cyclic test to understand seismic performance differences between cast-in-place (CIP) and precast bridge columns with various shear span-to-depth ratios and connection design details. The columns are designed based on practical engineering application, which aims to provide design reference for the seismic behavior of real-world bridge structures with varying column heights, such as bridge ramps. Based on the test results, it was found that column height exceeding the plastic hinge region is of combined bending and shear failure and that the full development of the plastic hinge region of these columns yields the same damage progression. However, short columns that are lower than the height of the plastic hinge are subjected to pure shear failure, and they are also of the same level of seismic performance except for displacement-related indices. Though the strengthening effect of the grouted splice sleeve connections is observed and damage is more concentrated at the joint for precast bridge columns, the difference of overall seismic performance between CIP and precast bridge columns is less than 5% in terms of ductility and energy dissipation. The addition of shear keys or change of bond material help improve the structural integrity, while the increase of seismic performance is still limited. [ABSTRACT FROM AUTHOR]

In electrical substations, glass-fibre reinforced polymer (GFRP) insulators provide an alternative to porcelain insulators for better seismic performance. The bonded connection between the composite tube and the metal end fitting is a weak link under earthquake actions, and the failure risk of ultra-high voltage (UHV) substation equipment with GFRP composite insulators can be considerable in places with high seismicity. This study solved the problem by retrofitting and experimentally qualifying the seismic performance of surge arresters made of composite insulators. To ensure safety under a bending moment corresponding to the seismic demand, the bonded sleeve joint between the tube and end fitting was retrofitted by shear stiffeners and higher strength end fitting. A full-scale shaking table test was carried out to verify the performance of the retrofitted surge arrester, and the seismic responses to increasing earthquake actions were analyzed. The specimens in this study were full-scale, had the largest dimensions among substation equipment of the same type, and were subjected to an extremely high earthquake action of 0.5 g; therefore, the seismic testing results produced in this study can serve as an important reference for the industry. [ABSTRACT FROM AUTHOR]

Earthquake prediction is a common scientific challenge for academics worldwide. This dilemma originates from the lack of precursory indicators that meet the sufficient and necessary conditions of earthquake occurrence, which may be the root cause of the failure of earthquake prediction. In light of this, a double-block catastrophic mechanics theory for earthquakes based on cross-fault Newton force measurement is proposed herein. Based on this theory and laboratory physical model tests of seismic Newton force monitoring, a new academic thought is envisioned "the sufficient and necessary condition for earthquake occurrence is the change of Newton force, and the sudden drop of Newton force on the fault surface can be used as a predictor of earthquake disaster." Several equipment systems have been independently developed, and the technology has been successfully applied to engineering practice. This concept has currently been proven in small-scale double-block catastrophic events such as landslides. Based on the double-block catastrophic mechanics theory, landslides and earthquakes have the similar nature but different scales. According to the on-site monitoring of landslides, it is verified that the sudden drop of Newton force can be used as a predictor of landslide disaster which successfully solves the problem of short-term landslide prediction. The introduction of cross-fault Newton force measurement technology and idea has laid a foundation for improving the method and level of international earthquake monitoring and solving the world-class scientific problem of short-term earthquake prediction. [ABSTRACT FROM AUTHOR]

Fire sprinkler systems damaged during earthquakes can compromise the functionality of a building facility either by loss of fire protection and/or by damage due to flooding. Shake table tests were conducted on a sprinkler piping specimen, with features representative of actual practices in New Zealand, to characterize its dynamic behavior under seismic floor excitation. The aim of the testing was to signify the need for a reliable procedure in the relevant New Zealand Standard (NZS 4541) for the estimation of seismic demands on these systems. The specimen was subjected to a set of motions including recorded floor acceleration response histories of an instrumented building in New Zealand. This paper first describes the test setup and the piping specimen and then discusses the seismic response of the specimen to multiple floor motions for different bracing variations. The testing showed that bracing segments of piping other than the distribution pipe modifies the dynamic characteristics of the system and consequently the seismic demands. The test results further confirm that seismic demands on pipes can be considerably greater if the system is in resonance with the floor excitation. Recommendations are provided for necessary improvements to NZS 4541 (2020) for a reliable estimation of seismic demands. [ABSTRACT FROM AUTHOR]

This study constructed a flatfile with the information useful to satisfy the site characterization requirements of Korea Meteorological Administration's seismic network, which was expanded significantly to 265 seismic stations following the 2016 Gyeongju Earthquake and the 2017 Pohang Earthquake in South Korea. Seismic response parameters, including the average seismic shear-wave velocity from the surface to a depth of 30 m (VS30), the depth of the engineering bedrock (H), and the mean VS of soils above the engineering bedrock (VS,Soil), were collected for each seismic station using existing available data and were obtained via direct in situ tests and explorations, including borehole drillings, downhole tests (DHTs), and surface seismic tests (multichannel analysis of surface waves [MASW]). To ensure the comprehensive coverage of all observation sites, terrain- and geological-map-based proxy techniques were applied to all stations. In addition to currently operational seismic stations, data on closed stations were collected and included as much as possible to enhance the accuracy of the seismic observational data at those points. For the 265 seismic stations, 28% of the representative VS30 values were obtained from geophysical investigations, such as DHTs and MASW, whereas 60% were collected using geotechnical in situ methods, such as boring and standard penetration tests. Twelve percent of the representative VS30 data were estimated using seismic records or proxy-based techniques. Finally, all observation sites were classified according to three engineering site classification systems: two internationally accepted VS30-based National Earthquake Hazards Reduction Program codes and an H- and VS,Soil-based Korean code. [ABSTRACT FROM AUTHOR]