Impulsive Motions Research Articles

A nonlinear structural pulse-like seismic response prediction method based on pulse-like identification and decomposition learning

Abstract Accurate prediction of structural responses under seismic action is important for the performance evaluation of structures. However, depending on the differences in the characteristics of ground motions, particularly whether they contain impulses, the seismic-response characteristics of structures may differ significantly. Hence, a new method, i.e., WD–AttDL, is proposed in this study to predict structural response under pulse-like ground motions. This method innovatively combines a wavelet decomposition-based velocity pulse-identification method with decomposition learning, where decomposed pulses and high-frequency features are used as inputs to the neural-network model, thus simplifying the identification of pulse features for the model. The decomposition learning module integrates different types of submodules, such as CNN feature-extraction, LSTM temporal-learning, and self-attention mechanism submodules. To reduce the nonlinear time-range analysis calculations required to generate training data, a screening method for impulsive ground motions based on time-series feature clustering is proposed. The accuracy and applicability of the proposed method are verified by numerically simulating three different cycles of reinforced-concrete frame structures and a three-dimensional masonry structure. Compared with existing structural seismic-response models, WD–AttDL synergistically integrates different modules and thus offers a higher prediction accuracy. In particular, it reduces the peak error of the predicted response, which is important for the evaluation of structural performance. Additionally, based on the response predicted by WD–AttDL, a vulnerability analysis of the structure under pulse-like seismic effects can be performed rapidly and accurately.

Analysis of impulsive ground motions from February 2023 Kahramanmaraş earthquake sequence

AbstractOn the 6th of February 2023, a large magnitude earthquake (Pazarcık earthquake), $$M_{w}=$$ M w = 7.7, occurred in southeast Türkiye, which caused significant destruction in Türkiye and Syria. Relatively large magnitude aftershocks followed the main shock, and after 9 hours of the main event, another large magnitude earthquake (Elbistan earthquake) occurred, $$M_{w}=$$ M w = 7.6, on a nearby fault. This study analyzes the near-fault seismic signals from earthquakes larger than 5.5 recorded between the main shock and the 31st of March 2023. More than 60 impulsive motions are detected in 3 earthquakes, mostly concentrated in the Pazarcık and Elbistan earthquakes. In the Pazarcık earthquake, many impulsive motions are recorded in near-fault stations with periods of up to 14 s. In contrast, in the Elbistan earthquake, impulsive motions are spatially distributed, with pulse periods of up to 11 s and at distances greater than 150 km. Pulse periods mostly correlate with the magnitude of the earthquake, but pulse probability models do not predict impulsive motions over long distances. The presence of strong impulsive motions in vertical components is also observed. For both earthquakes, peak ground velocities (PGVs) are larger than predicted by ground motion prediction equations. The observation of long-period, large amplitude signals may indicate the presence of a directivity effect for both earthquakes. In some stations, spectral periods exceed the 2018 Turkish building design codes for long periods ($$\ge$$ ≥ 1 s).

Significance of Pulse-Like Ground Motions and Directivity Effects in Moderate Earthquakes: The Example of the Mw 6.1 Gölyaka-Düzce Earthquake on 23 November 2022

ABSTRACT The 1400 km long North Anatolian Fault Zone in Türkiye runs through numerous densely populated regions, including the city of Düzce that was recently hit by an Mw 6.1 earthquake on 23 November 2022. This was the first moderate event in the region after the devastating Mw 7.2 earthquake in 1999, which cost the lives of over 700 people. Despite its moderate size, the earthquake caused unexpected severe damage to a significant number of buildings, as reported by local institutions (Disaster and Emergency Management Presidency, AFAD). It is well established that ground motions in the near field can lead to increased damage due to near-field domain effects, such as ground-motion pulses and directivity effects (i.e., when the site is aligned with rupture propagation). We examine potential near-field effects using the strong ground motion database of AFAD-Turkish Accelerometric Database and Analysis Systems. To achieve this, we first analyze the behavior of the ground-motion intensities in terms of their spatial distribution and observe higher peak ground velocity than expected by ground-motion models in spatially constrained azimuthal ranges. Furthermore, we find that the majority of the near-fault recordings contain velocity pulses that are primary concentrated on the fault-parallel component. This outcome questions the widely accepted understanding from the previous studies, which mainly suggested that impulsive ground motions that are associated with directivity effects primarily occur on the fault-normal component of large-magnitude events.

Seismic responses of liquid storage tanks subjected to vertical excitation of near-fault earthquakes

This study aims to evaluate the effect of vertical seismic component on dynamic responses of liquid storage tanks, with a special focus on near-fault earthquakes. A shaking table test was performed on a 1:25 scaled steel tank, which was loaded by both far- and near-fault ground motions with horizontal unidirectional, vertical unidirectional, and combined horizontal and vertical bi-directional excitations. Seismic responses, including sloshing height and hydrodynamic pressure were recorded and compared. Subsequently, a refined finite element (FE) model of the scaled tank model was established by utilizing the structured Arbitrary-Lagrange-Eulerian (S-ALE) solver and Fluid-Structure Interaction (FSI) algorithm, which was verified by comparison with the test results. Afterward, the modeling methodology was further applied to a prototype large-scale liquefied natural gas (LNG) inner tank for seismic analysis. In addition, seismic responses of the LNG inner tank were compared with the recommendations given in seismic design codes for cylindrical tanks. The experimental and numerical findings showed that both the convective and impulsive motions of liquid was amplified by vertical excitations, especially under near-fault earthquakes. The peak sloshing heights under near- and far-fault earthquakes were increased by 14–142% and 8–56% due to the existence of vertical action, respectively. The LNG inner tank was more vulnerable to inelastic buckling due to the presence of vertical seismic component. Moreover, the effect of vertical excitations of near-fault earthquakes on hydrodynamic pressure and tank stresses was underestimated by the current seismic design codes.

A reduced two-layer non-hydrostatic model for submarine landslide-generated tsunamis

The goal of this research is to develop an efficient numerical scheme for simulating the appearance of surface waves induced by submarine landslides. In this study, a reduced two-layer non-hydrostatic model is extended to include a time-varying solid bottom. This reduced two-layer non-hydrostatic scheme is computationally efficient, comparable to a one-layer scheme, but has the accuracy of a two-layer system. The accuracy and flexibility of the reduced two-layer non-hydrostatic scheme (abbreviated as NH-2LR) used here are explained by studying the dispersion relation. As benchmark tests, the NH-2LR model is validated using a variety of tsunami simulations generated by landslides, including impulsive vertical bottom motions, mass sliding on an inclined plane, and horizontal landslide motion. The numerical findings are shown to be in good agreement with the experimental observations, implying that the proposed model is a feasible alternative for modeling landslide-generated tsunamis. It is also shown that the new scheme reduces computational effort while maintaining high accuracy.

A unified approach for time-invariant and time-variant reliability-based design optimization with multiple most probable points

Reliability-based design optimization (RBDO) can fulfill performance-based design of static and dynamic structures considering various uncertainties. For time-invariant and time-variant RBDO problems with multiple most probable points (MPPs, also termed as design points), the existing approaches encounter some difficulties in searching for all MPPs and performing time-variant RBDO which requires complicated time-variant reliability analysis. In this paper, the direct probability integral method (DPIM) combining with the change of probability measure (COM), i.e., DPIM-COM approach, is proposed to attack time-invariant and time-variant RBDO problems with multiple MPPs in a unified framework. Firstly, the DPIM in conjunction with Heaviside function is developed to estimate time-invariant and time-variant probabilistic constraints directly and explicitly. Then, an efficient formula for calculating the sensitivity of probabilistic constraints with respect to random design variables is derived based on the DPIM and COM strategy, where the representative points for reliability computation keep unchanged and only the corresponding assigned probabilities need to be updated. Accordingly, the corresponding structural responses of representative points at the current design variables can be reused to evaluate the sensitivity of probabilistic constraints, which saves much computational cost, especially for time-variant RBDO problems. Finally, three numerical examples, including the ten-story building with tuned mass damper under deterministic earthquake ground motion and near-fault stochastic impulsive ground motions, demonstrate the effectiveness and versatility of the proposed DPIM-COM approach for addressing time-invariant and time-variant RBDO problems with multiple MPPs.

Dynamic recoil in metamaterials with nonlinear interactions

Biological systems can generate motions with high acceleration and velocity via dynamic recoil. Traditionally, recoil dynamics in unstructured linear elastic systems are based on inertial and elastic properties, with the recoil velocity determined by the materials' speed of sound and the strain at recoil. Metamaterials with designed elastic structures and nonlinear interactions (e.g., magnetic interactions) have recently demonstrated the capability to control impulsive motions and manage high-rate energy transfer events. However, a predictive model for understanding the kinematics and recoil dynamics has not been developed. Here, we study the dynamic recoil that couples with a general nonlinear power-law interaction within a metamaterial framework. Starting with a 1D discrete model, we demonstrate how the nonlinear force interactions and the elastic structures in metamaterials control the dynamic performance. Under a weakly nonlinear condition, the governing equation of the dynamic recoil is described by the KdV (Korteweg-de Vries) equation and under the condition of strong nonlinearity by a more general strongly nonlinear wave equation. Our model predicts a “sonic vacuum” response in the recoiling metamaterials, where a near-zero speed of sound is induced by strongly nonlinear interactions and zero initial prestress. We propose a sequential wave motion during the dynamic recoil, where a linear wave propagates at a large stretch and switches to a nonlinear one below a critical stretch. We further discover that the nonlinear wave speed has a non-monotonic dependence upon the strength of the power-law interaction. We find good agreements in the recoil velocity by comparing our analytical model to experiments of the recoiling metamaterials with magnetic interactions. Our work demonstrates how power-law interactions within metamaterials can program dynamic recoil dynamics, setting the stage for new materials designs for energy management and conversion in high-rate applications.

BB-SPEEDset: A Validated Dataset of Broadband Near-Source Earthquake Ground Motions from 3D Physics-Based Numerical Simulations

ABSTRACTThis article introduces a strong-motion dataset of near-source broadband earthquake ground motions from 3D physics-based numerical simulations—named BB-SPEEDset—obtained by the code SPEED (SPectral Elements in Elastodynamics with Discontinuous Galerkin)—developed at Politecnico di Milano, Italy. Taking advantage of the earthquake ground-motion scenarios produced so far by SPEED, in most cases validated against earthquake recordings, the main objective of this work is to construct and validate a dataset of simulated broadband waveforms to be used as a support for characterization and modeling of near-source earthquake ground motions. To pursue this objective, the following steps were necessary, namely: (1) the implementation of an effective workflow suitable to process in an homogeneous format various SPEED simulations; (2) the generation of broadband time histories using a technique based on artificial neural networks, trained on strong-motion records; (3) the creation of a flat file collecting, for each simulated scenario, the most relevant metadata (fault rupture scenario, site response proxies, source-to-site distances) as well as a comprehensive set of ground-motion intensity measures of the processed broadband waveforms (peak ground acceleration, velocity and displacement, spectral ordinates, duration, pulse period, etc.). Finally, a comprehensive set of consistency checks is made to verify the absence of any systematic bias in the trend of the BB-SPEEDset results with respect to the NEar-Source Strong-motion (NESS) version 2.0 near-source recorded ground-motion dataset. Indeed, the main features of near-source ground motion in BB-SPEEDset, ranging from the statistical distributions of peak and integral measures both at short and long periods, the ground-motion attenuation with distance, to the features of impulsive ground motions and directionality effects, are in substantial agreement with those from NESS.

Critical Analysis of Nonlinear Base-Isolated Building Considering Soil–Structure Interaction under Impulsive and Long-Duration Ground Motions

Critical responses are investigated for nonlinear base-isolated buildings considering soil–structure interaction under near-fault ground motions and long-duration ground motions. A double impulse and a multi impulse are employed to simulate the nonlinear critical responses of the models under such ground motions. The base-isolation story is assumed to consist of lead rubber bearings and to have a bilinear force–deformation relation. Two types of critical timings for a MDOF building model supported by a swaying-rocking spring-dashpot system are derived: (1) the timing that maximizes the total input energy to the whole system and (2) the timing that maximizes the instantaneous input energy to the base-isolated building excluding the swaying-rocking system. These two types of critical timings are compared through numerical examples. Finally, time-history response analyses were conducted under the critical double impulse, the corresponding one-cycle sine wave, and the critical multi impulse. The effect of the soil–structure interaction on the maximum responses of the nonlinear base-isolated building is clarified.

Impulsive Signals Produced by Earthquakes in Italy and Their Potential Relation with Site Effects and Structural Damage

Near fault seismic records may contain impulsive motions in velocity-time history. The seismic records can be identified as impulsive and non-impulsive depending on the features that their waveforms have. These motions can be an indicator of directivity or fling step effect, and they may cause dangerous effects on structures; for this reason, there is increasing attention on this subject in the last years. In this study, we collect the major earthquakes in Italy, with a magnitude large or equal to Mw 5.0, and identify the impulsive motions recorded by seismic stations. We correlate impulsive motions with directivity and fling step effects. We find that most earthquakes produced impulsive signals due to the directivity effect, though those at close stations to the 30 October 2016 Amatrice earthquake might be generated by the fling step effect. Starting from the analyzed impulses, we discuss on the potential influence of site effects on impulsive signals and suggest a characterization based on the main displacement directions of the impulsive horizontal displacements. Finally, we discuss on the damage of three churches in Emilia, which were subject to impulsive ground motion, underlying in a qualitative way, how the characteristics of the pulses may have had influences the structural response of the façades.

Reliability-based stochastic optimal control of frame building under near-fault ground motions

Most of stochastic optimal control methods were developed on the basis of Itô stochastic differential equation, which assumes that the external excitation is white Gaussian noise or filtered white Gaussian noise. However, this assumption is far from the real excitations, which hinders the applications of stochastic optimal control theory. In this paper, the reliability-based stochastic optimal control via direct probability integral method (DPIM) for building structure is proposed, which is applicable to performance-based design of general control systems of linear structures under non-stationary and non-white random excitations. Firstly, the DPIM is utilized to accurately and efficiently compute dynamic reliability of the controlled system. Then, the reliability-based objective function is suggested to optimize the parameters of the placed control devices of building structure, and reliability-based maximum story controllability index is established to determine the optimal placement of control devices, thus fulfilling the stochastic optimal control of structure. Finally, a 10-story shear frame building controlled by active tendons under random excitations of near-fault earthquake ground motions verifies the effectiveness of the proposed optimal control method. Moreover, the optimal control schemes of frame structure under near-fault non-pulse and impulsive ground motions are compared, indicating that the velocity pulses of near-fault ground motions impose significant effect on structural responses, and the more control energy is needed for guaranteeing structural safety.

Nonlinear Rocking Behavior of Irregular Anchored Rigid Bodies: Influence of Main Parameters and Anchoring Effectiveness

ABSTRACT The rocking response of anchored rigid bodies with irregular geometry is evaluated, incorporating the non-linearity of restrainers. A parametric analysis is performed, introducing the concept of Probability Reduction Spectra (PRS) to identify the influence of the main parameters into the rocking response as a function of the fundamental frequencies (excitation/body). The results allow identifying the conditions where anchoring systems are more suitable for different types of excitations. Restrainers have a better performance for slender bodies under impulsive motions (near source) with any eccentricity up to the center of geometry. For seismic excitations, from far or intermediate-depth sources, it is evident a PRS’ band where anchorage is effective. Independently of the kind of excitation, bodies with low and/or asymmetric center of mass could suddenly overturn under abrupt peak intensities after anchorage failure.

Unsteady flow of Carreau fluids around an impulsively moving cylinder

Unsteady flow of Carreau fluids around an impulsively moving circular cylinder is numerically investigated in this study. Both shear-thinning and shear-thickening fluids are used with the range of the power-index number 0.4 ≤ n ≤ 2. Unsteady laminar flow with the influence of shear-dependent viscosity and impulsive motions of the cylinder are analyzed with various Carreau numbers 10 ≤ Cu ≤ 40 and Reynolds numbers 10 ≤ Re ≤ 100. Both starting and stopping flows are numerically simulated. Systematic validation is conducted for current numerical approaches using literature data before the investigation of the unsteady flow. The effects of major Carreau fluid flow parameters, namely, n, Cu, and Re, on the unsteady vortical flow are studied with a focus on the formation of vortices, zero-shear point on the cylinder, and transitory hydrodynamic loads. In general, increased shear-thickening (n > 1 with higher Cu and lower Re) leads to higher viscous effect, delaying the formation of additional vortices and promoting the drag force due to the dominant viscous drag. More interesting flow aspects are noticed with shear-thinning fluids. Increased shear-thinning (n < 1 with higher Cu and higher Re) results in complicated vortical flow including secondary, tertiary, quaternary vortices, and even more. Highly oscillated drag force is obtained in such vortical flow due to the oscillated pressure drag, which dominates the total drag in the current unsteady flow. It is expected that the results reported in this study could be used for a better understanding of unsteady non-Newtonian fluid flow and for the validation of numerical simulation of unsteady non-Newtonian fluid flow.

Active structural control via metaheuristic algorithmsconsidering soil-structure interaction

In this study, multi-story structures are actively controlled using metaheuristic algorithms. The soil conditions such as dense, normal and soft soil are considered under near-fault ground motions consisting of two types of impulsive motions called directivity effect (fault normal component) and the flint step (fault parallel component). In the active tendon-controlled structure, Proportional–Integral–Derivative (PID) type controller optimized by the proposed algorithms was used to achieve a control signal and to produce a corresponding control force. As the novelty of the study, the parameters of PID controller were determined by different metaheuristic algorithms to find the best one for seismic structures. These algorithms are flower pollination algorithm (FPA), teaching learning based optimization (TLBO) and Jaya Algorithm (JA). Furthermore, since the influence of time delay on the structural responses is an important issue for active control systems, it should be considered in the optimization process and time domain analyses. The proposed method was applied for a 15-story structural model and the feasible results were found by limiting the maximum control force for the near-fault records defined in FEMA P-695. Finally, it was determined that the active control using metaheuristic algorithms optimally reduced the structural responses and can be applied for the buildings with the soil-structure interaction (SSI).

Dimensional response analysis of rocking wall-frame building structures with control devices subjected to near-fault pulse-like ground motions

This paper addresses the influences of control devices on the seismic responses of rocking wall-frame building structures based on dimensional analysis. Firstly, the flexural-shear beam is adopted to represent the rocking wall-frame buildings, and the control elements include concentrated control devices (CCD, e.g., precast tendons) and distributed control devices (DCD, e.g., dampers installed at floors). Particularly, the closed-form solutions are derived for the static and dynamic responses of the flexural-shear beam with concentrated and distributed control devices. Dimensional response analysis of rocking wall-frame buildings based on intrinsic scale shows that, the normalized seismic responses present complete self-similarity and harmonious order. Then, the vibration characteristics and static responses of the flexural-shear beam are examined. Results indicate that the fundamental period of rocking wall-frame buildings clearly decreases with strengthening DCD. The base moment resisted by the rocking wall remarkably increases with strengthening CCD, and both devices lead to a notable increase in the base shear of the rocking wall. Finally, the dimensional response analysis of rocking wall-frame buildings under near-fault pulse-like ground motions illustrates that, DCD generally suppresses interstory drift response sufficiently, but causes a significant drift concentration. In contrast, CCD does not clearly reduce interstory drift response, yet sufficiently avoids drift concentration. Additionally, both devices generally are not beneficial to control the floor acceleration responses to near-fault impulsive motions, especially DCD. Thus, the appropriate control device should be selected according to the responses concerned in the practical seismic design of buildings.

Extreme value distribution and dynamic reliability estimation of high-pier bridges subjected to near-fault impulsive ground motions

The seismic behaviour of high-pier and long-span bridges in fault zones is significantly influenced by the near-fault impulsive effect. In view of this, this study evaluates the extreme value distribution and dynamic reliability of high-pier bridges built in fault zones. First, based on the improved maximum entropy method constrained with fractional moments, a new method is proposed to evaluate the extreme value distribution of nonlinear structure seismic response. In the proposed method, the fractional moments are evaluated by the Latin hypercube sampling, and a linear system of equations that determine the initial value of fractional exponents and Lagrange multipliers is illustrated to improve the stability of the simplex algorithm. Second, based on the obtained extreme value distribution, the seismic reliability of structure is estimated by the simple numerical integration. Two numerical examples, including a nonlinear single-degree-of-freedom system and a three-storey nonlinear shear frame, are adopted to validate the proposed method. Finally, the seismic reliability of a typical high-pier and long-span continuous rigid frame bridge located in southwest of China is evaluated by the proposed method and some critical conclusions are drawn. The results obtained from this study not only indicate the accuracy and efficiency of the proposed method but also can provide some direct guidelines for the seismic design of the high-pier and long-span bridges in fault zones.

An Investigation on the Effect of the Near-Fault Earthquakes on the Seismic Behavior of RC Moment Resisting Frames (MRFs) Designed Based on Iranian Seismic Code (Standard No. 2800)

Past severe earthquakes, such as Bam earthquake of 2003 and Tabas earthquake of 1978, have demonstrated that many cities in Iran are prone to be struck by near-fault earthquakes. Such earthquakes are impulsive in nature, and therefore, they are more destructive than the ordinary ground shaking. In the fourth edition of Iranian seismic code (Standard No. 2800), some changes, including a modification factor for the elastic acceleration response spectrum (EARS) have been recently recommended to reflect the effects of such probable near-fault earthquakes for the designing procedure. In this study, a numbers of 2D RC moment resisting frames (MRFs), from four to twelve story buildings, are designed linearly based on Iranian National Building Code (INBC) and Standard No. 2800 as well. Subsequently, their nonlinear models are reproduced for conducting nonlinear dynamic time history (NDTH) analysis. For this purpose, twenty impulsive ground motions are selected and scaled to be compatible with the design basis earthquake (DBE) spectrum of the abovementioned code. It is concluded that the seismic performance of the analyzed structures are not satisfactory at all; no buildings are successful to satisfy the life safety (LS) performance level posed by guidelines such as ASCE41-06 or ASCE41-13. Moreover, it is worth mentioning that even collapse prevention (CP) limit states are not also met in some cases. Therefore, the recently added modifications in the Standard No. 2800 may be inadequate to incorporate the near-fault earthquakes' effects.

Analysis Of Concrete Tunnel Frameworks Subject To Fault Removal

An earthquake fault rupture generates two types of ground motion: permanent quasi-static dislocations and dynamic oscillations, characterized by strong pulses. This study investigates tunnel’s response to two different conditions using a 2D finite element program; the first one has a static dislocation corresponding to different earthquake magnitudes, while the second combines near-field seismic motions with three specific peak ground accelerations along with permanent dislocations. The impulsive ground motions affect the lining response further to other influential factors such as fault type and dip angle, making changes in sectional forces, displacement, and shear distortion of the lining. Moreover, pulse intensity, period, and frequency content are effective characteristics of impulsive motions that change in final response of the lining, subjected to subsequent static dislocations. Based on the second condition, at low PGAs, the pulse type is more effective to final response of the lining, due to forward and backward momentum specifications in impulsive motions. For earthquakes with high PGA and larger values in nearfield parameters, both the pulse type and period are effective. The tunnel displacement increases at PGAs as large as 0.7 and 1g, unlike the low PGA as large as 0.35g, because of increasing soil stress and plastic strain, respectively.

Unsteady flow of shear-thickening fluids around an impulsively moving circular cylinder

Unsteady flow past an impulsively moving circular cylinder in both Newtonian and shear-thickening fluids is investigated numerically. Two impulsive motions are simulated: impulsive start and impulsive stop. The Carreau viscosity model is used for shear-thickening fluids with the range of the power index 1 ≤ n ≤ 2. The Reynolds number is Re=40 base on the cylinder diameter. Simulation results of shear-thickening fluids are compared with the Newtonian case. Significant increase in the viscosity due to the impulsive motion impacts on flow features, including vortical structures, zero shear point on the cylinder surface, pressure profile, and the drag force. Current results indicate that vortical structures generated by the impulsive motion weaken and diffuse faster for a larger power index. The zero shear point on the cylinder surface is associated to the flow separation in impulsively started flow and the re-attachment in the impulsively stopped flow. The shear-thickening effect delays the separation and the re-attachment process, which is intertwined with slow development of adverse pressure gradient in shear-thickening fluids. The total drag increases as the power index increases. Contribution of the friction and the pressure drag to the total is discussed in details. The impact of the Carreau number Cu on the non-Newtonian behavior is numerically investigated as well.

Electrically-latched compliant jumping mechanism based on a dielectric elastomer actuator

Jumping mechanisms are useful in robotics for locomotion in unstructured environments, or for self-righting abilities. However, most rigid robots rely on impact with the ground to jump, thereby requiring a relatively rigid, and flat environment. Moreover, they need to be able to absorb high impact forces during landing in order to maintain structural integrity. In this paper we investigate soft systems, capable of jumping repeatedly in unstructured environments with no need for precise landings. Our impulsive approach is based on a soft electro-mechanical transducer, a dielectric elastomer actuator (DEA). The design is inspired by click-beetles and simple bio-mechanical models, which convert the flexing around a hinge into jumping. Our actuator is power amplified by the addition of a stiffer strip, allowing for rapid shape transitions (22 ms) between flat and curved states. The transition is controlled by an electric latch: the DEA is discharged faster than the actuator can deform. The mechanical energy stored in the composite beam is released rapidly, leading to impulsive motions (jumps of a full body length: i.e. 5 cm). This demonstration of an electrically-latched power amplification mechanism shows that relatively simple electro-mechanical systems can exhibit impulsive behavior which may enable new types of locomotion in compliant machines.