High Earthquake Intensity Research Articles

Vulnerability analysis of earthquake-driven blast load on a reinforced concrete structure

It is common practice in earthquake-prone areas to design structures with earthquake loading in mind. The severity of the damage to a structure depends on the earthquake's magnitude and the type of structure. Sometimes, a high-intensity earthquake can trigger explosive materials to explode inside structures. This combination of loading scenarios could lead to an overall increase in damage to the structures. So, it is essential to study the vulnerability analysis of the structures subjected to multi-hazard loading scenarios. This study mainly discusses the combined effect of the earthquake followed by the blast loading on the reinforced concrete structure. The results show that damage to the structure increases under combined earthquake and blast loading. Furthermore, the earthquake-induced vibrations in the structure intensify after the blast load. A parametric study of the structure is also performed, taking into account the possible load combinations of earthquake and blast loading. Moreover, this study discusses a numerical solution to the aforementioned problem, which strengthens fundamental knowledge and provides structural engineers with a deeper insight regarding the multi-hazard loading scenario considered in this study.

Seismic Design Optimization of Frame-multi-ribbed Composite Wall Structure

To explore the optimization seismic design of frame-multi-ribbed composite wall structure, firstly the finite element model of a six story frame-multi-ribbed composite wall structure is established based on the software of SAP2000. Secondly the critical design parameters of multi story frame-multi-ribbed composite wall structure under seismic action are analysised using finite element analysis software. Finally the seismic response of the structure under different rib combinations and the optimal arrangement rule of the structure are studied. The results reveals that the lateral stiffness of the structure cannot be effectively improved by increasing the number of rib grids of the multi ribbed composite wall. The results can provide a theoretical basis for the design of the multi story frame-multi-ribbed composite wall structure in the medium and high earthquake intensity area.

Energy spectra and performance assessment of isolated structures with a negative stiffness amplification system

Negative-stiffness-incorporated seismic isolation technology has been widely adopted for the effective protection of infrastructures from high-intensity earthquakes. In particular, by incorporating a dashpot and tuning spring, a negative stiffness device can yield a negative stiffness amplification system (NSAS) that can produce an amplified dashpot deformation without sacrificing the isolating effect. To address this observed amplification effect and unknown performances subjected to various types of ground motions, energy spectra are proposed in this study for structures equipped with the NSAS-incorporated isolation system (NSAS-IS) and classified by the field-type of ground motions, based on which the energy-spectrum-based performance evaluation method is developed. The basic concept and mechanical model of the negative-stiffness device, NSAS-IS, and pertinent isolated structure are introduced, based on which the energy response analysis model is established. Within the energy-based framework, the ground motions are classified, whereas the energy spectra are unified for the original structure and the NSAS-IS-equipped isolated structure with a series of typical NSAS-ISs. By addressing the near-, middle-, and far-field ground motions, analytical assessment formulae are provided for the NSAS-IS-equipped structures to quantify the differences in the seismic performances and enhanced energy dissipation levels among the various ground motions. Finally, the proposed energy-based performance assessment tool is applied in design cases for illustration. The findings of this study show that the developed energy spectra are effective in evaluating the energy dissipation enhancement and structural energy dissipation reduction levels of NSASs against various field-type earthquakes. Specifically, the energy dissipation burden of the superstructure under near-field ground motions with significant pulse components is larger than that of the middle- and far-field motions, signifying the necessity of considering the earthquake type for the performance assessment and design of NSAS-IS structures. The proposed analytical performance evaluation formulae can be adopted for a quick performance assessment of NSAS-IS isolated structures subjected to various earthquakes.

Magnetization distribution and susceptibility inversions of the Balapur fault in the northern region of Kashmir basin, NW Himalaya

Ground magnetic surveys were carried out in the northern region of the Kashmir basin, NW Himalaya to calculate the total magnetic intensities and subsurface constraints at the Balapur fault. The susceptibility index of -0.020 SI to 0.001SI was found associated with the strike of the Balapur fault. Further, the susceptibility index of the associated Gulmarg fault was recorded as -0.01SI to 0.001 SI. The present study implies that the Balapur fault has produced well-developed magnetic constraints throughout its strike. The 3D inversion modeling implies that the Balapur fault in north Kashmir has developed enough subsurface strain features and can lead to high earthquake intensity. Little or no variation was found between the observed and predicted databases and the analysis recorded an accuracy factor of 0.002 with 20 iterations. The study suggests that ground magnetic surveys are very useful in understanding the subsurface fault characteristics based on the Magnetization factor.

Quasi-static test study of tunnel with resistance-limiting shock absorption layer in high-intensity seismic

The Sichuan-Tibet Railway is faced with risks of active faults, unfavorable geological conditions, high in-situ stress levels, and a high potential for Traditional tunnel seismic measures that can no longer guarantee the safety of tunnel structures in high-intensity earthquake areas. The new shock absorption capacity layer with resistance-limiting is proposed in this paper and the resistance-limiting shock absorption principle. To study the safety of the new anti-shock lining structure, a large-scale quasi-static model test was carried out based on the improved static-dynamic coupling shear force. The test analyzes the response rules of strain, structural internal force, and lining failure form of tunnel lining, taking into consideration three influencing factors including layer layout position, layout density, and tunnel buried depth. The results showed that: 1) Under the action of low-cycle reciprocating shear strain, the failure mode of the shallow buried tunnel is mainly the tensile failure of the arch waist and the failure of the arch waist and the side wall, and the failure mode of the deeply buried tunnel is mainly the compression failure of the arch waist; 2) Compared with the case of no shock absorption layer, the lining tensile stress on the inner side of the arch waist position is significantly reduced. Under the high shear strain (0.20%), the increased tensile stress trend was slowed down on the inner side walls; 3) The main working area of the resistance-limiting layer can effectively improve the lining stress distribution underground vibration and protects the tensile damage on the arch waist to the side wall. The width and depth of the crack are weakened and the seismic bearing capacity of the width and depth of the crack is weakened and the seismic bearing capacity of the lining structure is greatly strengthened; 4) The lining cracks without the resistance limiting layer develop violently, and the crack at the arch waist runs The lining structure failure mode of the resistance limiting layer arranged at the arch waist is similar to The lining structure failure mode of the resistance limiting layer.

Simplified framework for economic convenience of base isolation as seismic retrofit solution for existing RC buildings

Modern seismic retrofit strategies aim at increasing the building safety under high intensity earthquakes and minimizing the possible damage and, in turn the expected economic losses (EAL) under frequent and low intensity earthquakes. Classic techniques based on tradition or innovative material such as steel jacketing or FRP wrapping aims at increasing the strength/ductility of reinforced concrete (RC) members, but they do not significantly act in reducing the engineering demand parameters EDPs such as acceleration and drift. On the other side innovative techniques such as base isolation are capable of combining the increase of seismic safety with the significant reduction of acceleration and drift demand on the superstructure, thus, resulting in a significant reduction of the EALs. Although the number of applications is significantly increasing in Italy, its wide use is discouraged by the high cost of installation. Considering the annual savings related to the reduction of the EALs, the payback time (PBT) of the economic investment in a retrofitting by using base isolation can be comparable to that of other techniques. However simple tools to easily assess the PBT knowing major building characteristics are currently not available.This paper proposes a novel framework to estimate the EALs and the PBT of RC buildings retrofitted by means of FRP or Base Isolation based on the main building characteristics (i.e. in-plane geometry, number of floors, seismic). It is implemented in a MATLAB code to perform NLTHs on simplified structural models and calculate the EALs by using the full PBEE framework and considering the uncertainties in the hazard, damage and loss analysis. The framework is validated against the results of a case study building analyzed by means of a refined 3D FEM model and calculating the EAL by means of the FEMA P-58 approach. A parametric study is carried out varying the concrete compressive strength and the reinforcement details to check the sensitivity of the framework to these variables. The preliminary results are presented and discussed.

The devastating 06.02.2023 Turkey – Syria earthquake of extreme intensity XI: Aposteriori estimates and damage prevention

The recent devastating earthquake of Mw7.8 occurred on February 6, 20223 in the Kahramanmaraş region having extreme intensity (XI) on the modified Mercalli scale (MMS) caused the death of more than 52,800 people in Turkey and Syria, as well as severe damages to the infrastructure. The appearance of an unusually strong delta-like S-wave pulse in the seismogram of the main shock and its consequences are analysed, and possible measures to mitigate the possible future high intensity earthquakes are discussed.

Performance evaluation of high-rise apartment building using pushover analysis

Indonesia is a developing country that is experiencing rapid development growth. According to the Central Statistics Agency, in 2020 the population of Indonesia will be 270.20 million people. The increase in population from year-to-year results in increasingly narrow lands for development. Therefore, developers and businesspeople make the best use of this opportunity in the world of construction by carrying out developments, including high-rise apartments. As an earthquake-prone area, the planning process for buildings, especially tall buildings in Indonesia, must be carried out very carefully by considering the strength of the structure against high-intensity earthquake loads. Risk reduction strategies can be implemented through building vulnerability assessment by checking structural performance using pushover analysis. In this study, the performance of a 32-storey apartment building was examined using the pushover analysis method. The resulting calculation is that the performance of the structure is 0.0023 for the lateral direction and 0.0113 for the transverse direction. Through the ATC 40 method it is known that the result of structural performance is Damage Control, where after an earthquake the building is still habitable.

Value-Based Seismic Performance Optimization of Steel Frames Equipped with Viscous Dampers

ABSTRACT Recent studies showed that while code-compliant structures can generally protect the safety of the occupants, they may exhibit extensive damages during strong earthquake events. On the other hand, structures are generally designed to satisfy the seismic code requirements with the least initial cost regardless of their life cycle cost. In recent years, value-based design has been considered as an effective alternative for code-based design procedures. In this method, as well as the initial cost of the structure, a comprehensive consequence modeling is performed in the design process. In this paper, for the first time, a value-based design optimization method is developed for seismic enhancement of existing RBS steel frames using nonlinear viscous dampers. The efficiency of the method is demonstrated through 4-, 8-, and 12-story frames designed for low, medium, and high earthquake intensity levels, while the life cycle costs are evaluated using FEMA P-58. A time-based approach is carried out to consider different earthquake events and their corresponding probability of occurrence in a specific range of intensities. For dynamic analysis of the structures, the Endurance Time (ET) method is adopted to significantly reduce the computational costs while providing accurate results. The Genetic Algorithm (GA) is then used to optimize the damping coefficient of the viscous dampers for minimum life cycle cost. The results, in general, indicate the efficiency of the proposed method in increasing the total economic value of the studied structures with the least additional cost. It is shown that shorter structures and those designed in high-seismic risk regions benefit more from using optimized viscous dampers, leading to up to 42% lower life cycle costs. The results of this study should prove useful in more efficient strengthening design of existing steel frames.

Performance and strength analysis of concrete-encased steel plate walls under tensile-flexural-shear load

When located at the base of a building experiencing high-intensity earthquakes or bi-directional earthquakes, shear walls may be tensile, resulting in tensile-flexural-shear (TFS) stress states after lateral load coupling. The Chinese code proposes the embedded steel to counteract such issues, but there are few relevant studies. Six concrete-encased steel plate (CES) walls were tested under the TFS load to investigate the effects of axial tensile ratio and steel content on seismic behavior. The results showed that TFS specimens failed in tensile flexural-shear mode. Compared to the tension-free specimen, TFS specimens with an axial tensile ratio of 2.5 had 21%, 56%, and 40% lower shear strength, initial lateral stiffness, and ductility. Comparatively, increasing the steel content in the boundary elements effectively reduced the strengthening effect of steel and the brittle fracture potential of boundary elements induced by TFS load, thus enhancing the overall behavior by 15–19%. Furthermore, the failure mechanism was proposed based on the development of deformation and strain. It demonstrated that the maximum principal tensile stress in the web caused severe shear strength degradation and highlighted the importance of the dowel action through the crack interface, depending on the variables. Through the comparative analysis of the shear strength design formulas for eccentric tensile CES walls, the steel proportion was proposed as a modified factor in Chinese code for better estimation.

Model validation of carbon-fiber and glass-fiber reinforced elastomeric isolators using finite element method

Fiber Reinforced Elastomeric Isolators (FREI) is a base isolation innovation for low-rise buildings suitable for developing countries with high earthquake intensity, for instance, Indonesia. The extension of the basic natural fundamental period by FREI will result into a reduction in floor acceleration when an earthquake occurs, thereby it will be reducing the inter-story drift movement in the superstructure. The FREI mass structure is lighter for low-rise buildings due its components consist of a layer of rubbers and a sheet of fibers. This study investigated numerically the use of fiber materials (glass and carbon fibers) for FREI reinforcement using ABAQUS program. The analysis results were evaluated based on mechanical characterization, including vertical and horizontal stiffness, effective horizontal stiffness, and damping ratio. The mechanical characterization in numeric research will be compared with experimental research as a research validation to ensure the input material variables are reliable and valid. Based on the analysis of numeric research results, CFREI and GFREI indicated that hysteresis curves and mechanical characterization were quite close to experimental research. Calculation of mechanical characterization in CFREI and GFREI refers to the regulations of BS_EN_1337:2005 and BS_EN_15129:2009. A deviation of mechanical characterization on numeric research of both specimens against the experimental research, including effective horizontal stiffness and damping ratio, indicated a fairly small deviation with less than 10%. The deviation between the maximum effective horizontal stiffness in CFREI and GFREI was 4.733% and 0.672% respectively, meanwhile the maximum damping ratio in CFREI and GFREI indicated the larger deviation that was 0.812% and 8.679% individually.

Seismic Performance Evaluation of a Multi Storey RC Structure Subjected to Strong Ground Motions

Abstract: A tremor or a movement of the ground occurs during an earthquake on Earth's surface. Earthquakes can also cause landslides and volcanic eruptions. Natural disasters or human activity can produce earthquakes, which are defined as seismic events generating seismic waves. Earthquakes most commonly occur when geological faults rupture, however they can also occur as a result of volcanic eruptions, landslides, mine explosions, and nuclear testing. The study of structural behavior towards different ground motions is therefore one of the main criteria to determine damage intensity. Structural Analysis of a residential building is carried out by using ETabs Software. Present study is intended to study the dynamic behavior of Multistorey Reinforced Concrete structure by considering, an existing G+13 storey residential building is modeled and its structural behaviour is studied using Time history method by considering different high intensity earthquakes. The behaviour of the building is studied mainly for its base shear, Storey displacement and maximum joint displacement.

The Development of a Holistic and Inclusive Model for Disaster Priority Regeneration Area (DPRA): The Case of Istanbul, Turkey

Urban regeneration can be defined as a multi-functional, specifical zoning application for the improvement and sustainability of an urban area with its physical, environmental, social and economic conditions. The question of where the urban regeneration will take place constitutes the primary pillar of the applications. Considering the expected high-intensity earthquake in Istanbul, there is a significant number of risky regions in the earthquake zone that need to be regenerated. The important part of reducing damage in an earthquake disaster is improving the quality of the building stock. The identification, prioritization, analysis and visualization of disaster priority regeneration areas (DPRAs) is possible by creating a functional model based on a spatial basis. The main element in the scope of this study is to establish the processes related to the DPRAs and to determine the necessary criteria for the determination of these areas. Analyzing how much the existing DPRAs overlap with the areas suggested in this study and creating basis for the needed model in order to identify the undeclared areas, the destruction and losses that may be caused by the earthquake in the coming years can be prevented by the implementation of this sustainable and integrated urban regeneration model.

Geospatial Analytics for Preliminarily Landscape Active Tectonic Assessment of the Wadi Araba Basin, Western Gulf of Suez, Egypt

The Gulf of Suez area represents one of the most famous tectonic structures in the Red Sea, with a long history of low-, moderate-, and high-intensity earthquakes. This paper provides geomorphic analytics of the fault-initiated mountain front sinuosity (Smf) and the stream gradients that cross various segments of the fault scarps. The results from the mountain front sinuosity index (Smf) and the valley floor width to valley height ratio index (Vf) suggest different levels of activities along the different fault segments. The analysis of the stream gradient index reflects that streams running through the fault segments mostly have higher river gradient values identified by knickpoint spots. With regard to the strike variation in the mountain front sinuosity, valley floor width to valley height ratio, and stream river gradients, the results are compatible with the predominant mountain front’s relief. Finally, the calculated geomorphic results show that the eastern segments might reflect higher seismic signals with respect to the central and western segments of the entire Wadi Araba basin. Thus, more careful studies are required to investigate seismic hazard possibilities.

Seismic analysis of a base-isolated reinforced concrete frame using high damping rubber bearings considering hardening characteristics and bidirectional coupling effect

High damping rubber bearings (HDRBs) are commonly used in base isolation systems, which can protect the structures from heavy earthquake damage by elongating natural vibration periods of the structures and improving the energy dissipation capacity of the systems. For the HDRBs, the stiffness hardening effect is exhibited at large shear strain, which is favorable to control the displacement of the bearings. Meanwhile, the horizontal hysteretic behavior in the two orthogonal directions is coupled and related to the path history. Here, the influence of the stiffness hardening and bidirectional coupling effects of the bearings on the seismic responses of the isolation system is studied. The full-scale quasistatic cyclic tests of two HDRB specimens with different dimensions were carried out under unidirectional and bidirectional loads. In the numerical analysis, the DHI and the classical Bouc-Wen model are used to simulate the hysteretic behavior of the HDRBs, in which the DHI model can capture the increased damping and stiffness, and bidirectional coupling properties. The parameters of both bearing models are determined according to the test results. Time-history analyses of a six-story reinforced concrete (RC) frame building with an HDRB isolation system are carried out for a suite of earthquake ground motions. The influence on seismic response of superstructure and isolation layer is analyzed with or without considering the hardening effect and bidirectional coupling effect of HDRBs. The results demonstrate that with consideration of the stiffness hardening and coupling effects, the peak responses of the superstructure significantly increase under high-intensity earthquakes. The analytical results suggest that the stiffness hardening and the effect of bidirectional coupling of the HDRBs should be considered in the design for HDRB isolation systems.

Reliability Analysis for Liquefaction Risk Assessment for the City of Patna, India using Hybrid Computational Modeling

ABSTRACT In the present study, the first-order reliability method (FORM) is applied to evaluate the failure of soil deposits during seismic excitation for the city of Patna, India. Patna is emerging as one of the metro cities and the rapid infrastructure development in the city with high pace construction of road and metro services along with several smart city projects have led to immense growth in civil engineering structures. Therefore, liquefaction assessment of Patna is an important subject due to the geographical and seismic location of the city. A detailed comparative study has been performed between first-order second moment (FOSM) and advanced first-order second-moment (AFOSM) reliability methods to determine the most suitable method to evaluate the potential risk of liquefaction for Patna city. Reliability index (β) values obtained from AFOSM analysis are in true accordance with the deterministic approach and therefore can be considered as an appropriate tool for reliability analysis for this city. The analysis establishes that the city of Patna exhibits high possibilities of liquefaction failure during high-intensity earthquakes i.e. Mw = 6.5. Also, a concept of a predictive computational model developed by the hybridization of ANN and GWO algorithms to determine β value using geotechnical and seismic parameters has been proposed. The high precision and error-free performance of the ANN-GWO model provides a powerful computational tool to assist the prediction of β. The results of the study could be used to comprehend the potential risk against liquefaction and provide a novel and insightful concept of risk assessment for safe and economic construction practices.

Selection and modification of ground motion records using a weighted scaling method based on the Newmark-Hall target spectrum

For the problem of the selection and modification of ground motions in nonlinear time-history analysis, a weighted scaling method based on the Newmark-Hall target spectrum (WNM) was developed in this study. The average Newmark-Hall spectra of the three ground motion sets developed in the SAC Steel Project are defined as the target spectra, which represent 50 %, 10 %, and 2 % probabilities exceeded in 50 years, respectively. The matching errors (SSE) and scaling factors (SF) were calculated by the weighted least-squares method to match with the Newmark-Hall target spectrum. The 9- and 20-story steel-moment-resisting frame structures were used as examples. Their mean structural responses obtained by the WNM were compared with the results of the method using the Newmark-Hall target spectrum without weight in scaling records (NM). Both the WNM and WN can control the relative errors of the prediction of the mean structural response within ± 20 % as compared with the benchmark results when 7 or 10 records are selected, if the SSE and SF used to scale and rank a record are both obtained by the same scaling method. Both the WNM and NM have better capacity for reducing the variability of structural responses than the acceleration target spectrum method. Especially for the 20-story structure with long fundamental period in regions with high earthquake intensity, this advantage of the WNM is more prominent than that of the WN. In addition, if the record has a large forward and back displacement peak, the steel-moment-resisting frame structures would produce a large offset at the low half of the building, and the panel zones are critical components for the structural deformation.

Comparative and parametric study of AI-based models for risk assessment against soil liquefaction for high-intensity earthquakes

Comparative and parametric study of AI-based models for risk assessment against soil liquefaction for high-intensity earthquakes

Developing a Disaster Chain Method to Evaluate Transportation Systems: A Pilot Study of Predicting Debris Blockages in Disaster-Response Road Systems

Suitable transportation systems are vital for the functioning of urban areas. Such systems connect all major locations, including residential and commercial locations, in these areas. The effectiveness of the response of an urban area to an earthquake depends on the road system in the area. A feasible and efficient approach to evaluating the capacity of road systems to allow safe and efficient emergency transportation for affected residents in the aftermath of an earthquake should be developed. Ground transportation systems are vulnerable to earthquakes. For example, ground motion in the 1994 Northridge, 1995 Kobe, 1999 Chi-Chi, and 2018 Hokkaido earthquakes caused severe damage to urban roads and bridges. Moreover, for areas with a high building density that are prone to high-intensity earthquakes, it is important to be able to estimate the risk of road blockage caused by collapsed buildings. In the present study, a disaster impact chain was established to evaluate the probability and effects of buildings collapsing in an earthquake. This chain was used as the basis for a road blockage model and for the formulation of suitable procedures and methods for earthquake response. The results of this study indicate that buildings in strong-motion zones are severely damaged by high-intensity earthquakes. Falling debris from these buildings can lead to the blockage of rescue roads, delaying the transport of injured individuals to hospital after an earthquake. The results of this study can aid authorities in making decisions related to transportation system management during earthquake disasters.

Analisis Perbandingan Kinerja Seismik dari Struktur Gedung dengan Pelat Konvensional, Waffle Slab, dan Flat Slab

Indonesia is a country with high earthquake risk because it is located in the path of the most active earthquake in the world. It makes Indonesia situated in a region with a high earthquake intensity. The study aimed to determine the seismic performance levels of building structures with conventional slabs, waffle slabs, and flat slabs with the time history analysis method. There are three models of structures studied, namely building structures with conventional plates, building structures with waffle slabs, and building structures with flat slabs, with a 5-story structure system, where the longest and shortest span has the same size of 20 m and the height of each level 4 m. This study showed the largest displacement was 235.82 mm in building structures with waffle slabs and the smallest displacement was 146.49 mm in building structures with flat slabs. The largest drift is 0.012 on a building structure with a waffle slab, and the smallest drift is 0.007 on a building structure with a flat slab. The level of seismic performance produced from all three types of structures varies from immediate occupancy (IO) to damage control (DC).