Earthquake Energy Dissipation Research Articles

Development of a pseudostatic method for seismic performance evaluation of rocking bridge foundations

AbstractPseudostatic analysis can be an efficient approach to evaluating the dynamic response of structures for a preliminary design. In this paper, we present a pseudostatic method based on a pushover analysis to assess the seismic performance of bridge piers supported by rocking‐governed shallow foundations. The method has two stages. In the first stage, the capacity spectrum method (CSM) is applied to evaluate the maximum acceleration and displacement response of the bridge system. To have an appropriate system damping ratio in the CSM, we propose a method to consider various earthquake energy dissipation mechanisms for the pier and foundation. In the second stage, the footing settlement is evaluated based on the maximum footing rotation; an incrementally cyclic pushover analysis with a fixed footing rotation increment is performed to estimate the footing settlement. Examples are presented to demonstrate the applicability of the proposed method and the results of the proposed method are compared with the dynamic analysis results. Compared with the conventional CSM, the proposed method improves the estimation of system damping and can estimate the settlement after earthquakes.

Semi-active structural vibration control with magnetorheological damper based on hybrid fuzzy sliding mode controller

Recently, structural vibration control has proved its capacity to save lives and keep structures safe during earthquakes. Furthermore, there is a wealth of research in both numerical and experimental studies. As a result, due to its simplicity and performance in mitigating structural vibrations generated by ground motions, semi-active control played a significant role in the majority of these studies. Nonetheless, the magnetorheological damper is the most often used semi-active device. In particular, the rheological fluid properties have gained adequate attention in earthquake energy dissipation and structural vibrations management, particularly in the civil engineering field. The semi-active control of three scaled excited structures is addressed in this study. A magnetorheological damper operated by a hybrid fuzzy sliding mode controller ensures the proposed control. However, to provide the appropriate current for the damper to operate, this proposed intelligent controller is combined with a clipped optimum algorithm. Otherwise, the numerical simulation results of the seismic excited scaled structure demonstrate the resilience of the suggested controller. As a result, four time-scaled seismic data are applied to the tested structure. Finally, the usefulness of the suggested semi-active control technique in mitigating earthquake structural vibration is demonstrated clearly in the compared controlled and uncontrolled responses.

Reliability interpretation of redundancy on design and seismic behaviour of steel conveyors

ABSTRACT This study investigates the effect of redundancy incorporation as static indeterminacy and possibility to utilise alternative load paths in design and seismic behaviour of steel truss bridge conveyors by conducting complementary reliability assessments. The results could be supportive in adjusting the degree of indeterminacy, especially for long structures, to convince the design goals. It is conceived that the design approach with lower indeterminacy donates to less structural weight in addition to a bit more fundamental period contributing to less earthquake-induced demands and easily controllable lateral drifts in the end reference points which are very crucial in view of connecting to the adjacent structures. On the other hand, providing more indeterminacy in conveyor design could bring about more ductility, nonlinear displacement and earthquake energy dissipation as well as closer nonlinear behavioural parameters to the amounts recommended by the design code. In reliability assessments by increasing the degree of indeterminacy, the failure probability is reduced which contributes to the design with higher reliability indexes and higher collapse safety margin and it is expected that the incorporation of redundancy effects would be more perceivable by providing models with more redundancy discrepancy.

Low Dissipation of Earthquake Energy Where a Fault Follows Pre‐Existing Weaknesses: Field and Microstructural Observations of Malawi’s Bilila‐Mtakataka Fault

AbstractDuring earthquakes on low (<1–2 km) displacement faults in isotropic crust, more earthquake energy is consumed by fracturing and gouge formation than in ruptures along more mature faults. To investigate how pre‐existing weaknesses affect earthquake energy dissipation along low displacement faults, we studied fault rocks from the 110 km long, 0.4–1.2 km displacement, Bilila‐Mtakataka Fault (BMF), Malawi. Where the BMF is parallel to surface metamorphic fabrics, macroscale fractures define a narrow (5–20 m wide) damage zone relative to where the BMF is foliation‐oblique (20–80 m), and to faults with comparable displacement in isotropic crust (∼40–120 m). Enhanced microfracturing and widespread gouge formation, typically reported from comparable‐displacement faults, are not observed. Therefore, minimal evidence for earthquake energy dissipation into the BMF’s surrounding wall rock exists, despite geomorphic evidence for MW 7.5–8 earthquakes. We attribute this finding to differences in earthquake energy partitioning along incipient faults in isotropic and anisotropic crust.

The effect of strain rate and temperature on the hysteresis of shear dampers of LY225 low-yield-strength steel

In a passive-controlled structure for seismic protection, energy dissipating devices such as steel dampers are supposed to concentrate earthquake energy dissipation and to sustain strain amplitudes and strain rates much larger than those in primary structural elements. The self-heating and the moderate strain rate in the order of magnitude of 1 s−1 may have non-negligible effects on the hysteresis behavior of dampers. To investigate this combined effect, eleven full-scale shear dampers of LY225 steel were subjected to either dynamic or quasistatic cyclic loading at shear strain amplitudes of 2.00–10.0 %. The comparison between the dynamic and quasistatic hysteresis curves shows that the strain-rate effect alone increased the shear strength of the dampers by 8.0–11.6 %, while the elevated temperature due to self-heating significantly accelerated the decrease in the shear strength of the dampers during dynamic loading. A one-dimensional rheological model is proposed and calibrated based on the test results to simulate the strain-rate and temperature dependencies of steel dampers. It offers a promising tool for improved simulation of the seismic response of steel dampers in nonlinear response history analyses.

Numerical Investigation of Energy Dissipation Device to Improve Seismic Response of Existing Steel Buildings with Soft-First-Story

Retrofitting buildings in densely populated areas with a soft story configuration on the first floor can pose a daunting challenge to the community. Against this backdrop, this study set out to evaluate the seismic retrofit strategy's adequacy in enhancing the seismic performance of buildings with a soft story. The proposed strategy utilizes an earthquake energy dissipation device consisting of a combination of a diagonal brace and a metallic-yielding damper at the ground story level. Two prototype buildings, one with five and the other with ten floors, were chosen to assess the proposed retrofit strategy's seismic response through nonlinear static and dynamic analyses. The seismic capacity, lateral displacement response, maximum inter-story drift ratio, energy dissipation, and collapse fragility are the major response parameters used to compare original and retrofitted buildings. The nonlinear static analysis results revealed that the seismic capacity for buildings equipped with a yielding damper was higher than that of the original buildings. It was also found that retrofitted frame buildings had a desirable structural behavior with a higher value of dissipated energy and a lower value of residual displacements and inter-story drift ratio, in turn reducing the likelihood of soft-story failure.

A Study on the Significance of the Design Parameters of Steel Plate Shear Walls Subjected to Monotonic Loading

Steel plate shear walls (SPSWs) as a resistant system against lateral loads have a high potential for earthquake energy dissipation. Due to the uncertainties of loading, construction, and installation of SPSWs, it is vital to investigate the importance of each component and achieve higher accuracy in design and the implementation of these members. In this paper, a sensitivity analysis is carried out to determine the significance of important uncertainties. The results denoted that the most important parameters affecting the loading capacity of the SPSWs are height, thickness, length, Young’s modulus of the wall material, flange, and web thickness of the column, respectively.

Theoretical and experimental studies on tapered plate-rubber isolator

Earthquake is one of the biggest threats for multi-story buildings in the developing countries. Thus, a cost-effective base isolation bearing is designed to overcome the challenge. Tapered plate-rubber isolator consists of a set of cover plates and a detached rubber interlayer, which can balance seismic isolation and economic expenditure. Theoretical and experimental studies will focus on the hysteretic behaviors. Energy consumption of three design parameters is discussed, including the slope of the tapered plane surface, elasticity and thickness of the rubber sheet. Effective stiffness and damping ratio are derived by the hysteretic energy dissipation curves, and finally shaking table test is set up to evaluate the structural reaction. Results indicate that tapered plate-rubber isolator can dissipate seismic energy efficiently, which will minimize the dynamic responses of the superstructure. Low-cost, easy manufacture and high earthquake energy dissipation will support it to be an efficient isolation bearing for the multi-story buildings.

Effects of pulse-like nature of forward directivity ground motions on the seismic behavior of steel moment frames

In the structures with high level of ductility, the earthquake energy dissipation in structural components is an important factor that describes their seismic behavior. Since the connection details play a major role in the ductile behavior of structure, in this paper, the seismic response of 3-, 5- and 8-story steel special moment frames (SMFs) is investigated by considering the effects of panel zone modeling and the influence of forward-directivity near-field ground motions. To provide a reasonable comparison, selected records of both near and far-field are used in the nonlinear time-history analysis of models. The results of the comparison of the median maximum inter-story drift under excitation by near-field (NF) records and the far-field (FF) ground motions show that the inter-story drift demands can be obtained 3.47, 4.86 and 5.92 times in 3-, 5- and 8-story structures, respectively, undergoing near-field earthquakes.

Numerical simulation of bridge piers with spread footings under earthquake excitation

This study simulates the responses of large-scale bridge piers under pseudo-dynamic tests to investigate the performance of four types of numerical models that consider the nonlinear behavior of the pier and the rocking behavior of the footing. In the models, beam-column elements with plastic hinges are used for the pier, two types of foundation models (rotational spring and distributed spring models) are adopted for the footing behavior, and two types of viscous damping models (Rayleigh and dashpot models) are applied for energy dissipation. Results show that the nonlinear pier model combined with the distributed spring-dashpot foundation model can reasonably capture the behavior of the piers in the tests. Although the commonly used rotational spring foundation model adopts a nonlinear moment-rotation property that reflects the effect of footing uplift, it cannot suitably simulate the hysteretic moment-rotation response of the footing in the dynamic analysis once the footing uplifts. In addition, the piers are susceptible to cracking damage under strong seismic loading and the induced plastic response can provide contribution to earthquake energy dissipation.

Energy and asset value elasticity of earthquake-induced direct economic losses

Major earthquakes usually release massive energy with a strong destructive force on human life and property. Nevertheless, how earthquake-induced direct economic losses (DELs) depend on earthquake energy dissipation and asset value exposure is still rarely known. Based on the estimated asset value exposure and the estimated earthquake energy for DELs produced by earthquakes over the period from 1990 to 2016 in China, the economic concept of elasticity is used to quantify the statistical relationship between DELs, asset value exposure and earthquake energy. The results show that asset value exposure and earthquake energy are correlated with earthquake DELs. On average, changes in asset value exposure have been relatively more important in explaining earthquake DELs than changes in earthquake energy. Moreover, a doubling in asset value exposure increases the DEL by 60% while a doubling in energy dissipation leads to a 31% increase in the DEL, and these results could be used for DEL predictions for new emerging earthquakes. This study suggested that the accumulation of wealth in earthquake-prone regions under economic growth will inevitably increase DELs if there are no changes in mitigation efforts. These findings also emphasize human behavior in determining the difference between a hazard and a disaster and provide significant insights in urban planning and disaster risk reduction strategies.

Thermal Alteration of Pyrite to Pyrrhotite During Earthquakes: New Evidence of Seismic Slip in the Rock Record

AbstractSeismic slip zones convey important information on earthquake energy dissipation and rupture processes. However, geological records of earthquakes along exhumed faults remain scarce. They can be traced with a variety of methods that establish the frictional heating of seismic slip, although each has certain assets and disadvantages. Here we describe a mineral magnetic method to identify seismic slip along with its peak temperature through examination of magnetic mineral assemblages within a fault zone in deep‐sea sediments cored from the Japan Trench—one of the seismically most active regions around Japan—during the Integrated Ocean Drilling Program Expedition 343, the Japan Trench Fast Drilling Project. Fault zone sediments and adjacent host sediments were analyzed mineral magnetically, supplemented by scanning electron microscope observations with associated energy dispersive X‐ray spectroscopy analyses. The presence of the magnetic mineral pyrrhotite appears to be restricted to three fault zones occurring at ~697, ~720, and ~801 m below sea floor in the frontal prism sediments, while it is absent in the adjacent host sediments. Elevated temperatures and coseismic hot fluids as a consequence of frictional heating during earthquake rupture induced partial reaction of preexisting pyrite to pyrrhotite. The presence of pyrrhotite in combination with pyrite‐to‐pyrrhotite reaction kinetics constrains the peak temperature to between 640 and 800°C. The integrated mineral‐magnetic, microscopic, and kinetic approach adopted here is a useful tool to identify seismic slip along faults without frictional melt and establish the associated maximum temperature.

Effect of thermal regime on the seismic response of a dry bridge in a permafrost region along the Qinghai-Tibet Railway

Dry bridges have been widely applied in the Qinghai-Tibet Railway (QTR) to minimize the thermal disturbance of engineering to the permafrost. However, because the Qinghai-Tibet Plateau is an area with a high potential occurrence of earthquakes, seismic action can easily destroy the dry bridges. Therefore, a three-dimensional numerical model, with consideration of the soil-pile interactions, is established to investigate the thermal characteristics and their impact on the seismic response of the dry bridge in permafrost region along the QTR. The numerical results indicate that there exist significant differences in the lateral displacement, shear force, and bending moment of the piles in different thermal conditions under seismic action. When the active layer become from unfrozen to frozen state, the maximum displacement of the bridge pile reduces, and the locations of the zero and peak values of the shear force and bending moment also change. It is found that although the higher stiffness of frozen soil confines the lateral displacement of the pile, compared with unfrozen soil, it has an adverse effect on the earthquake energy dissipation capacity.

Critical behavior in earthquake energy dissipation

We explore bursty multiscale energy dissipation from earthquakes flanked by latitudes 29° S and 35.5° S, and longitudes 69.501° W and 73.944° W (in the Chilean central zone). Our work compares the predictions of a theory of nonequilibrium phase transitions with nonstandard statistical signatures of earthquake complex scaling behaviors. For temporal scales less than 84 hours, time development of earthquake radiated energy activity follows an algebraic arrangement consistent with estimates from the theory of nonequilibrium phase transitions. There are no characteristic scales for probability distributions of sizes and lifetimes of the activity bursts in the scaling region. The power-law exponents describing the probability distributions suggest that the main energy dissipation takes place due to largest bursts of activity, such as major earthquakes, as opposed to smaller activations which contribute less significantly though they have greater relative occurrence. The results obtained provide statistical evidence that earthquake energy dissipation mechanisms are essentially “scale-free”, displaying statistical and dynamical self-similarity. Our results provide some evidence that earthquake radiated energy and directed percolation belong to a similar universality class.

Developing of steel plate shear walls braced with slidable multiple X-shaped restrainers: Hysteretic analyses and design recommendations

This paper proposed a light-weight buckling restrained steel plate shear wall (XSPSW) to improve the earthquake energy dissipation of unstiffened steel plate shear walls. It consisted of two slidable multiple X-shaped restrainers placed on the either side of a steel infill plate. The two restrainers could continue to provide out-of-plane restraint for infill plates to achieve stable energy dissipating capacity under cyclic reversal loads. Theoretical analyses and numerical simulating analyses have been conducted to investigate the hysteretic behaviors of XSPSWs and the stability of their sub-plates. Based on the analysis results, it could be concluded that the proposed XSPSWs were efficient lateral-load resisting members for the buildings in high seismic regions.

Earthquake protection of the Torre Grossa medieval tower of San Gimignano, Italy by vertical external prestressing

Abstract This paper presents an application of a methodology for the seismic vulnerability reduction of masonry towers by reversible prestressing. The approach is applied on a medieval tower located in San Gimignano, Italy, which is considered as a world heritage site. The 3D FE models are calibrated with experimental data and assessed by nonlinear static analyses including the seismic demand of the site and an accurate validated masonry model. The vertical prestressing is applied at key points identified in the seismic vulnerability assessment. This technique is in compliance with the demand for architectural conservation because it may be fully reversible. The seismic performance is enhanced by increasing force, displacement and internal confinement. It is observed at ultimate limit conditions an upgrading of 14.3% of displacement with the medium prestressing level and 9.5% with the high level. The results are analyzed and discussed in terms of earthquake energy dissipation and failure mechanisms.

Evaluation of response modification factor for steel structures with soft story retrofitted by viscous damper device

The soft story located in the basement of tall buildings for parking or shopping lot. Considering the limitation in architecture, these structures may be retrofitted by implementing earthquake energy dissipation such as viscous damper devices in soft story level. Nevertheless, an extensive review of related literature indicates that the effect of viscous damper on response modification factor is not considered. Therefore, this study proposed the response modification factors for steel structures furnished with viscous damper devices in soft story level and investigated the effect of implementing such devices on the response modification factor. In this research, steel structures with numerous stories were considered to evaluate the response modification factor, which was formulated based on three aspects, namely, strength, ductility, and redundancy factors. Quasi-static nonlinear analysis was performed using finite element software based on structural models equipped with damper devices installed in different locations of the parking level. No open bay is available in other floors to install the damper devices. Meanwhile, the overstrength, ductility, and response modification factors were established by conducting pushover analysis. Results of the study revealed that the response modification factors for structures equipped with damper devices are higher than those of structures without damper devices. Moreover, the value of response modification factor was affected by the number of stories and number of dampers. Considering the analytical results for different cases, the equation for determining the response modification factor for steel structures furnished by viscous damper devices in soft story level was proposed.

Seismic heating signatures in the Japan Trench subduction plate-boundary fault zone: evidence from a preliminary rock magnetic ‘geothermometer’

Frictional heating during earthquake rupture reveals important information on earthquake mechanisms and energy dissipation. The amount of annealing varies widely and is, as yet, poorly constrained. Here we use magnetic susceptibility versus temperature measurements during cycling to increasingly elevated temperatures to constrain the maximum temperature a slip zone has experienced. The case study comprises sheared clay cored from the Japan Trench subduction plate-boundary fault zone (decollement), which accommodated the large slip of the 2011 Mw 9.0 Tohoku-oki earthquake. The decollement was cored during the Integrated Ocean Drilling Program (IODP) Expedition 343, the Japan Trench Fast Drilling Project (JFAST). Heating signatures with estimated maximum temperatures ranging from ∼300 to over 500 °C are determined close to the multiple slip surfaces within the decollement. Since it is impossible to tie a specific slip surface to a certain earthquake, thermal evidence for the cumulative effect of several earthquakes is unveiled. This as yet preliminary rock magnetic ‘geothermometer’ would be a useful tool to detect seismic heating along faults that experienced medium temperature rise, a range which is difficult to assess with other approaches.

Adapted Bouc-Wen Analytical Model for Romanian SERB-C Seismic Dampers Used in Buildings Protection System

In this paper is presented a new mathematical model which is intended to simulate the hysteretic phenomenon of SERB-C Romanian friction device for damping and dissipation of earthquake energy used for buildings. These devices have unusual shape of force-displacement loop which can be simulated with our new model which represents a specific adaptation of the well known Bouc-Wen hysteretic model. The purpose of this analytical simulation is to determine a relation for the hysteretic loop which was obtained by experimental tests performed by the authors. The mathematical model presented in this paper can be used in computational simulation of a building protected with these types of devices, in order to determine the anti-seismic performances of a Romanian friction building protection system.

Analytical Model for Viscous Wall Dampers

AbstractBy now, many civil engineering researchers have extensively studied the application of earthquake energy dissipation systems in seismic‐resistant buildings. Earthquake energy dissipation systems play an important role in enhancing the sustainability of structures against seismic excitation. Frame buildings are strengthened by installing damper devices as supplemental structural members. This article presents the finite‐element‐based development of an analytical model for a viscous wall damper (VWD) device, an alternative to other earthquake energy dissipation systems, which can diminish the effect of earthquakes on structures and improve the seismic performance of multistory buildings subjected to ground motion. The constitutive law of VWDs has been formulated and integrated to develop a finite element model of VWD compatible with the reinforced concrete (RC) structure analytical model. Then, the finite element algorithm has been developed for inelastic analysis of RC buildings equipped with VWD devices capable of detecting damage to both structural members and damper connections under dynamic loading. Based on the developed system, the special finite element program was codified and verified by applying it to a real model of a RC building with supplementary VWD devices. Influence of VWDs on seismic performance of the RC building during earthquake excitation was evaluated. The proposed analytical model for VWD is verified by using experimental test data and analysis result proved that this energy dissipation system succeeds by substantially diminishing and dissipating a structure's induced seismic responses. Also the parametric study indicated that the damping coefficient is very effective on performance of VWD.