Seismic Response Research Articles

Discretization of small‐scale, stratigraphic heterogeneities and its impact on the seismic response: Lessons from the application of process‐based modelling

AbstractReducing the uncertainty of reservoir characterization requires to better identify the small‐scale structures of the subsurface from the available data. Studying the seismic response of meter‐scale, stratigraphic heterogeneities typically relies on the generation of reservoir models based on outcrop examples and their forward seismic modelling. To bridge geological information and seismic modelling, these methods allocate values of acoustic properties, such as mass‐density and P‐wave velocity, according to discretized properties like layer‐type lithology or facies units. This strategy matches the current workflow in seismic data inversion in industry, where modelling workflows are based on lithofacies distributions. However, from stratigraphic modelling, we know that meter‐scale heterogeneities occur within certain facies and lithologies. Here, we evaluate the difference on the seismic response between allocating acoustic properties in a grain size–based, semi‐continuous manner versus discretized manners based on lithology and facies classifications. To do so, we generate a reference geological simulation that we populate with acoustic properties, mass‐density and P‐wave velocity, using three different strategies: (1) based on grain size distribution; (2) based on facies distribution; and (3) based on lithology. The method we propose includes the generation of realistic geological simulations based on stratigraphic modelling and the transformation of its output into acoustic properties, honouring the intra‐lithology and intra‐facies, small‐scale structures. We, then, generate seismic data by applying a forward seismic modelling workflow. The synthetic data show that the grain size–based simulation allows the identification of small‐scale, stratigraphic heterogeneities, such as beds with strong density and velocity contrasts. These stratigraphic structures are smoothened or may completely disappear in the facies and lithology discretized simulations and, therefore, are not (well) represented in the synthetic seismic data. Recognizing meter‐scale, stratigraphic heterogeneities is relevant for the characterization of the fluid flow in the reservoir. However, current discrete and lithology‐based strategies in seismic inversion are not able to resolve such heterogeneities because real subsurface properties are not discrete properties but continuous, unless there are stratigraphic discontinuities such as erosional surfaces or faults. This research works towards a better understanding of the relationship between changes in these continuous properties and the observed seismic data by introducing greater complexity into the discretized geological simulations. Here, we use synthetic seismic images with the goal of eventually aiding in fine‐tuning seismic inversion methodologies applied to real seismic data. One pathway is to foster the development of inversion approaches that can leverage stratigraphic modelling to get stronger geological priors and replace the standard but inadequate multi‐Gaussian prior.

Seismic Characterisation of Hydraulic Fractures Influenced By Granitic Coarse Grains

Abstract The extensive application of hydraulic fracturing in unconventional reservoirs raises new challenges in understanding the fracture mechanism of granitic materials. Triaxial hydraulic fracturing experiments were conducted to examine the influence of coarse grains on the failure behaviour of impermeable granites based on the associated seismic responses. The waveform frequencies in laboratory hydraulic fracturing are predominantly below 600 kHz, with a dominant frequency around 200 kHz. Source mechanism analysis reveals that tensile cracks constitute the largest proportion among all crack types while have smaller magnitudes than non-tensile cracks. The micro-cracks are induced prior to fracture initiation which delays the immediate macro rupture, following peak injection pressure by the dilatancy hardening effect. The tensile cracks contribute to the increase in damage volume while the non-tensile ones lead to a reduction effect. Overall, the total damage volume escalates as average grain size increases. Granites have event magnitude less than -6.0 and b-values greater than 2. Small magnitude seismic events take less dominance of proportion with increasing grain size. Larger average grain size and lower grain size heterogeneity weaken the cementation between mineral grains, triggering larger boundary cracks. These cracks result in greater offset distance between multiple fractures and increase fracture tortuosity, also leading to longer failure duration, stronger seismic detectability, and a larger slip plunge range and average degrees.

Three-Dimensional Seismic Response Characterization Considering Soil-Reticulated Shell-Frame Structure Interaction

This paper investigates the soil-reticulated Soil Structure (shell-frame) Interaction (SSI) and its seismic response analysis under vertically incident seismic waves. By establishing the mechanical model of the three-dimensional oblique sliding friction seismic isolator (3D OSFSI), the effectiveness in reducing vertical responses is analyzed. The simulation of seismic waves and the automatic application of equivalent nodal forces are realized by using viscoelastic artificial boundaries and ABAQUS software combined with Python scripts. A comparison of the model with and without consideration of SSI found that the SSI effect will increase the peak value of nodes and the axial force of rods, three-dimensional seismic isolation can reduce the structural response, and the effect of different soil parameters is significant, weak soil due to the characteristics of the structural acceleration response of the smallest, so the mesh shell should be considered in the analysis of the seismic response of the site conditions and the effect of soil parameters.

Evaluation of geological hazard susceptibility based on the multi-kernel density information method.

The increasing occurrence of geological hazards along roadway infrastructures presents a significant concern. Evaluating geological hazard susceptibility along roads is a critical aspect of geological disaster emergency response and rescue efforts. Accurate evaluation outcomes are essential as they play a crucial role in mitigating potential financial losses. However, previous studies on geological hazard susceptibility treated all samples as independent entities, overlooking their spatial interactions. This study introduces a novel geological hazard susceptibility assessment model termed the multi-kernel density information (MKDI) method. The MKDI method integrates information value with kernel density estimation, effectively capturing the spatial dependencies among samples. Furthermore, distinct bandwidths are prescribed for various scales of disasters to facilitate multi-kernel density estimation for geological hazards. The integration of the information method enables the development of a comprehensive geological hazard susceptibility map, capturing the spatial complexities of geological hazard distribution. To validate the effectiveness of the proposed method, the study area selected for investigation was the G219 National Highway within Zayu County. Various factors were considered for geological hazard susceptibility mapping, including slope, aspect, profile and plan curvature, river and road linear densities, peak ground acceleration, seismic response spectrum characteristics, lithology, elevation, rainfall, and landform. The results show that the MKDI model outperformed previous methods, achieving an AUC value of 0.99. The derived susceptibility map is expected to offer a scientific basis for urban planning, construction, and geological hazard risk management in the study area.

Fragility assessment of steel jacket offshore platforms using time series prediction with deep learning methods

ABSTRACT Seismic evaluation is important in disaster susceptibility and prediction of structural failure under different seismic conditions. While fragility curves and Incremental Dynamic Analysis (IDA) are particular techniques, traditional methods are typically time-consuming and difficult. In this study, the response of a Steel Jacket Offshore Platform is predicted using time series forecasting models, particularly Gated Recurrent Units (GRU) and Long Short-Term Memory (LSTM). The performances of these forecasting models were evaluated by comparing their results with IDA and fragility curves, which are crucial for the evaluation of the platform's seismic vulnerability. The GRU model showed better accuracy and closer agreement with the time series of inter-level drift ratios, IDA curves, and fragility curves. The proposed method can potentially improve the accuracy of seismic response predictions in critical structures and give more credible information on how the structure would react to seismic forces.

Nonstationary Stochastic Responses of Transmission Tower-Line System with Viscoelastic Material Dampers Under Seismic Excitations

The excessive vibration or collapse of a transmission tower-line (TTL) system under seismic excitation can result in significant losses. Viscoelastic material dampers (VMDs) have been recognized as an effective method for structural vibration mitigation. Most existing studies have focused solely on the dynamic analysis of TTL systems with control devices under deterministic seismic excitations. Studies focusing on the nonstationary stochastic control of TTL systems with VMDs have not been reported. To this end, this study proposes a comprehensive analytical framework for the nonstationary stochastic responses of TTL systems with VMDs under stochastic seismic excitations. The analytical model of the TTL system is formulated using the Lagrange equation. The six-parameter model of VMDs and the vibration control method are established. Following this, the pseudo-excitation method (PEM) is applied to compute the stochastic response of the controlled TTL system under nonstationary seismic excitations, and a probabilistic framework for analyzing extreme value responses is developed. A real TTL system in China is selected to verify the validity of the proposed method. The accuracy of the proposed framework is validated based on the Monte Carlo method (MCM). A detailed parametric investigation is conducted to determine the optimal damper installation scheme and examine the effects of the service temperature and site type on stochastic seismic responses. The nonstationary stochastic seismic responses of the TTL system are consistent with those based on MCM, validating the accuracy of the proposed analytical framework. VMDs can effectively suppress the structural dynamic responses, with particularly stable control over displacement. The temperature and site type have a notable influence on the stochastic seismic responses of the TTL system. The research findings provide important references for improving the seismic performance of VMDs in TTL systems.

Seismic Performance Assessment of Insulated and Conventional Cross‐Arms Transmission Tower‐Line System

ABSTRACTThe electrical safety gap between conductors and trees can be increased by substituting insulated cross‐arms for conventional cross‐arms, which is increasingly used in the rehabilitation of existing transmission lines. To study the seismic performance of insulated cross‐arm transmission tower structures, this paper establishes transmission single tower and tower‐line system finite model and performs mechanical analysis of the cross‐arm and nonlinear dynamic response analysis of the structure under 150 seismic conditions of different parameters. The relationship between seismic strength and structural response is fitted, and the seismic performance of the transmission tower structure is evaluated. The results show that by substituting insulated cross‐arms for conventional cross‐arms, the maximum displacement of the vertex of the single tower and tower‐line system model can be reduced by 20.43% and 111.83%, respectively; when PGA = 0.2 g, the probability of collapse of a single tower structure and a tower‐line system can be reduced by 0.49% and 11.66%, respectively. The research in this paper provides a useful reference for the further application of insulating cross‐arms.

Interface boundary technique of hybrid test for seismic ground response analysis

Interface boundary technique of hybrid test for seismic ground response analysis

Optimized reduction of the seismic floor acceleration response in multistory buildings with supplemental viscous dampers

Optimized reduction of the seismic floor acceleration response in multistory buildings with supplemental viscous dampers

Seismic response of steel frames with hysteretic dampers designed according to second generation of Eurocode 8 and comparison with conventional frames

Seismic response of steel frames with hysteretic dampers designed according to second generation of Eurocode 8 and comparison with conventional frames

Influence of modeling choices on seismic response of a steel reticulated dome

Influence of modeling choices on seismic response of a steel reticulated dome

Seismic analysis of double-decker elevated water tank

Double-Decker Elevated Water tank is used for storage of large quantity of water. Direct source of water in water tank is from the rainfall. Taking water from tank for drinking, household & etc purpose is economical in that place where construction of well, bore well, etc is costly and area is less. Elevated water tanks are integrated part of lifeline facilities elevated water tank is storage container construction for the purpose of holding water supply. A large number of water tank is damage during past earthquake. So, there is need to focus on seismic safety. The aim of this paper to propose a seismic response of double-decker elevated water \tank in different zone and comparison with single elevated water tank. To study different types of load acting on it, bending moment an shear force and its displacement if any after seismic load is applied on water tank by using staad-pro software.

The application of time domain boundary element modeling for investigating the seismic response of deep alluvial basin and Rayleigh waves generation

The application of time domain boundary element modeling for investigating the seismic response of deep alluvial basin and Rayleigh waves generation

Novel Scissor‐Jack‐Damper With Spatial Configuration and Enhanced Efficiency

ABSTRACTFor a seismic damper, an enlarged damping effect accompanied with a pronounced economic feature (e.g., smaller damper size) is always expected. Commonly, the damper is installed in or linked to the primary structure via some connecting components, whereas the damper and its connecting component act in series. Owing to the limited stiffness of the connecting component, the deformation of the damper could be suppressed, thus weakens the damper's efficiency. To deal with this problem, amplification devices such as the toggle‐brace‐damper and the scissor‐jack‐damper (SJD) have been proposed. In these proposals, a geometrical converting scheme is adopted to transfer the inter‐story drift of the structure to the stroke of the damper. Compared with the toggle‐brace‐damper, the SJD shows a smaller space demand and lower dependency on the stiffness of the connecting components, thus exhibits a better potential for the practical application. To date, most of (if not all) the SJDs are installed in an inter‐story scenario to mitigate the inter‐story drift of building structures. In such cases, the out‐of‐plane instability issue of the SJD is not pronounced since the size of the SJD is not quite large. As the demand of using SJDs in the large‐scale scenarios keeps increase, the out‐of‐plane instability of the SJD starts to draw attention. In view of this problem, a novel 3‐dimensional SJD (3D SJD) configuration is proposed in this study. The 3D SJD achieves better global stabilities, thus facilitates its application in some large‐scale scenarios. The mechanical models of the 3D SJD with different degrees of complexity are derived, and a simplified mechanical model is validated against finite element simulations. An example of the application of the 3D SJD is reported. The results prove, in a quantified way, that the 3D SJD is highly efficient for mitigating the structural seismic response in large‐dimensional scenarios, and the 3D SJD exhibits an elevated energy‐dissipation ability compared with the conventional damper arrangement.

Nonuniform response spectrum incorporating real mode decomposition for seismic response analysis of boundary-SSI systems featuring dual nonclassical damping

Nonuniform response spectrum incorporating real mode decomposition for seismic response analysis of boundary-SSI systems featuring dual nonclassical damping

Seismic response of masonry pagodas considering soil-structure-interaction (SSI) effect and CFRP reinforcement

This study examines the seismic reinforcement of pagodas, a component of historical heritage, by initially evaluating the impact of soil–structure interaction (SSI) on the seismic response of pagodas, which was determined to substantially elevate the danger of damage to these structures. The study suggests a way to enhance the seismic performance of the pagoda by reinforcing it with carbon fiber-reinforced polymer (CFRP) composites. The lightweight, high-strength, and corrosion-resistant characteristics of CFRP render it a suitable material for reinforcing the pagoda. The primary tensile stress analysis revealed the pagoda’s vulnerabilities, leading to the strategic application of CFRP reinforcement. The strengthening methods substantially enhanced the seismic performance of the pagoda, mitigated the brittle damage traits of the masonry structure, diminished the extent of tensile damage, and extended the damage time frame of the building. The study’s results validate that the CFRP strengthening technique offers an effective novel solution for the seismic reinforcement of masonry structures, with potential for widespread adoption and application.

The influence of potential source parameters of novel near-fault synthetic ground motions on nonlinear cross-stream seismic response for high-arch dams based on conditional mean spectrum

The influence of potential source parameters of novel near-fault synthetic ground motions on nonlinear cross-stream seismic response for high-arch dams based on conditional mean spectrum

A separated three-dimensional isolation system for mitigating seismic response of ultra-high voltage converter transformer: Shaking table test and numerical simulation

A separated three-dimensional isolation system for mitigating seismic response of ultra-high voltage converter transformer: Shaking table test and numerical simulation

Seismic Damage Identification of Masonry Pagodas Based on Wavelet Packet Energy Variation

ABSTRACTA method for identifying structural damage in masonry pagodas based on wavelet packet energy variation was proposed, with the change in wavelet packet energy of dynamic response signals before and after structural damage being used as the damage indicator. Finite element software was employed to establish a numerical model of the Kaiyuan Pagoda. By introducing different types of damage and applying seismic waves in three directions under four working conditions, a seismic response analysis was conducted. The acceleration response signals at feature points on each floor of the structure were subjected to wavelet packet transformation, and the wavelet packet energy was calculated. Based on the wavelet packet energy variation (DSI), damage indicators were determined, and structural damage identification was carried out. The identification results were compared with the preset damage. The results showed that, in the absence of noise interference, the damage indicators clearly correlated with the damage of the masonry pagoda, enabling accurate localization of the damage. Even when Gaussian white noise was added to the acceleration dynamic response signals, the indicators could still accurately identify the damage location, demonstrating good noise resistance. The research results provided an effective method for the damage assessment of masonry pagodas.

Seismic response analysis of marine undulating sites based on indirect boundary element method

Seismic response analysis of marine undulating sites based on indirect boundary element method