Energy Balance Principle Research Articles

Study of the in-plane crashworthiness performance of 6-legged starfish-inspired structures

Bio-inspired design is an impressive design method that improves a structure's crashworthiness performance and mechanical features. A cellular structure bio-inspired by a 6-legged starfish shape has been developed. Accordingly, this study examines the in-plane crushing behavior and crashworthiness of the 6-legged starfish-inspired structure (6LSIS). Analytical solutions were built based on the principle of energy balance to estimate the plateau stress in low-impact velocity conditions. Plateau stresses are related to high-impact velocities using a curve fitting method for a given wall's thickness. The predictions matched the numerical results. The crashworthiness performance of the 6LSISs mainly depends on wall thickness, impact velocity, and loading direction. It has been observed that an increase in wall thickness and impact velocity results in an enhancement in plateau stress ( σpl), specific energy absorption (SEA), and peak load (PL) in both directions. However, if the wall thickness is >0.3 mm, SEA decreases due to an increase in the structure's mass. The in-plane crushing direction ( X or Y) determines the crushing strength and deformation mode of the structure. This study illustrates that the crashworthiness of the structure in the X-direction is superior to that in the Y-direction.

Integration of microwave satellite soil moisture products in the contextual surface temperature-vegetation index models for spatially continuous evapotranspiration estimation

The contextual surface temperature-vegetation index (TVX) models have been widely used for the retrieval of soil moisture (SM) and evapotranspiration (ET). One of the key premises for their application is to determine quantitatively the theoretical boundaries of this contextual TVX space. Usually these theoretical boundaries are determined based on land surface energy balance principle. Although sound in physical mechanism, the complex parameterization involved has hampered its remote sensing (RS) applications. Our recent studies show that ground-based SM observations can be used for a quick and continuous retrieval of these theoretical boundaries. The main disadvantage lies in its reliance on in-situ SM observations. Fortunately the development of microwave RS technology has made it possible to monitor SM at both regional and global scale. Under this background, a practical framework based on the contextual TVX models was proposed in this paper for continuous ET estimation through the combination of microwave-based SM products and MODIS (Moderate Resolution Imaging Spectroradiometer) products. Daily actual ET over the Southern Great Plains of the United States of America was calculated as the product of net radiation and evaporative fraction (EF). The focus of this framework was to investigate how optical and microwave RS can be combined to achieve a quick and continuous retrieval of EF independently of ground observations. Specifically, EF was retrieved from the contextual TVX models, the theoretical boundaries of which were calibrated at the annual scale based on an optimization scheme. Assuming the seasonal variation of the theoretical dry edge follows a cosine function of solar zenith, the essence of this optimization scheme is to search for the optimal amplitude parameter that maximizes the correlation between microwave-based SM observations and soil moisture index retrieved from the contextual TVX models. Two microwave-based SM products including SMAP (Soil Moisture Active Passive) and SMOS (Soil Moisture and Ocean Salinity) were adopted to demonstrate this optimization scheme. The correlation coefficient, root mean square error and bias of EF estimates calibrated by SMAP were 0.700, 0.146 and 0.047, and those achieved by SMOS were 0.663, 0.174 and 0.168, respectively. The optimization scheme has not only made it possible to conduct a continuous monitoring of ET based entirely on RS observations but also achieved the downscaling of microwave satellite SM products. Thus the combination of optical and microwave RS holds great potential for coupled and continuous estimation of SM and ET over large scale.

A Hybrid Submodule Three-Phase Multiplexing Arm Modular Multilevel Converter With Wide Operation Range and DC-Fault Blocking Capability

Three-phase multiplexing arm modular multilevel converter (TPMA-MMC) possesses lower cost, smaller volume, and higher efficiency compared with MMC. However, the limited operation range limits its popularity. Hence, in this article, it redefines arm submodule (SM) configuration type, where the conventional arm is configured with full-bridge submodules (FBSMs), and the multiplexing arm is formed by half-bridge submodules (HBSMs). Meanwhile, a new energy balance principle and modulation scheme are proposed to expand TPMA-MMC’s operation range. Furthermore, the DC-fault blocking schemes could be implemented to realize DC-fault tolerance reliably without the multiplexing arm blocking. Compared with hybrid MMC(H-MMC), it could reduce by 33.33% in submodules a least, which leads lower footprint and operation loss. Due to reregulating the energy flowing path of multiplexing arm, and rearranging the chain-link voltage of multiplexing and conventional arm, it could reduce the required SM capacitance and further decrease 65% energy storage requirement, resulting in improving the power density. Finally, the topology control scheme and DC-fault blocking scheme are verified by simulation and scale-down prototype experimental results.

Axial compression testing and constitutive model of a novel BF-reinforced ambient-cured LEGC

Ambient-cured lightweight expanded polystyrene geopolymer concrete (LEGC) currently undergoes early shrinkage cracking, and the low density of EPS causes segregation during the mixing process, resulting in a significant decrease in the strength of LEGC. To solve the above problems to obtain higher strength LEGC and promote its wide application, uniaxial compression tests and constitutive modeling studies of LEGC with different basalt fiber (BF) lengths (3 mm, 6 mm, 9 mm, 12 mm and 15 mm) reinforced with different expanded polystyrene (EPS) volume contents (10%, 20%, 30% and 40%) were conducted in this study. First, the damage pattern of the specimen was analyzed, and the crack development morphology was analyzed based on the Digital Image Correlation-3D (DIC-3D) technique. Additionally, the mechanism of BF-reinforced of LEGC was analyzed comprehensively at three levels: micromechanical theory, microscopic (scanning electron microscopy, SEM) and mesoscale (computerized tomography, CT). Empirical formulas for peak stress, peak strain, threshold stress, threshold strain and elastic modulus were established based on the stress‒strain curves of the specimens. In addition, the specific form of the damage evolution equation considering the energy dissipation of the specimen was derived from the energy balance principle and basic laws of irreversible thermodynamics based on composite damage theory. Finally, elastic‒plastic damage constitutive models established previously and in this study were compared, and the results showed that the method proposed in this study can better reflect the damage evolution of BF- reinforced LEGC.

THSI-RP: A two-tier hybrid swarm intelligence based node clustering and multi-hop routing protocol optimization for wireless sensor networks

Wireless sensor networks exploit clustering and routing techniques to improve energy efficiency, but these methods are generally considered as a non-deterministic polynomial (NP-hard) problem. To tackle this problem, we propose a novel two-tier hybrid swarm intelligence-based hierarchical routing protocol (THSI-RP). In the first tier, THIS-RP incorporates a hybrid swarm intelligence algorithm that combines Grey Wolf Optimization (GWO) and Marine Predators Algorithm (MPA) for the clustering algorithm. By incorporating the wolf factors from GWO into MPA as elite predators, we enhance the network search efficiency. This algorithm achieves adaptive optimal clustering with a controllable scale, considering the residual energy of nodes, relative distance between nodes, and node centrality. In the second tier, the routing algorithm uses a hybrid SI algorithm based on GWO and the graph model. First, we integrate distance and energy factors to dynamically select forwarding nodes using GWO. Then, based on the distance and energy balance principle, a weight cost function is established and combined with the minimum spanning tree method to construct a communication routing tree between the forwarding node and the base station to achieve optimized inter-cluster multi-hop routing. Simulation results demonstrate that THSI-RP outperforms several typical routing protocols in various metrics over EEUC, LPSO, LGWO, and LACO. For instance, THSI-RP achieves percentage improvement total packets by 290%, 10.9%, 8.9%, 19.9%, respectively. It also performs better in FND by 88.7%, 10.9%, 8.6%, and 16.3%, in HDN by 86.6%, 8.1%, 6.3%, and 17.1%, and in ADN by 41.7%, 8.2%, 6.4%, 18.3%.

Performance Analysis of Four Conceptual Designs for the Air Based Photovoltaic / Thermal Collectors

The thermal and electrical performance of different designs of air based hybrid photovoltaic/thermal collectors is investigated experimentally and theoretically. The circulating air is used to cool PV panels and to collect the absorbed energy to improve their performance. Four different collectors have been designed, manufactured and instrumented namely; double PV panels without cooling (model I), single duct double pass collector (model II), double duct single pass (model III), and single duct single pass (model IV) . Each collector consists of: channel duct, glass cover, axial fan to circulate air and two PV panel in parallel connection. The temperature of the upper and lower surfaces of PV panels, air temperature, air flow rate, air pressure drop, wind speed, solar radiation and ambient temperature were measured. The power produced by solar cells is measured also. A theoretical model has been developed for the collector model IV based on energy balance principle. The prediction of the thermal and hydraulic performance was obtained for the fourth model of PV/T collector by developing a Matlab computer program to solve the numerical model. The experimental results show that the combined efficiency of model III is higher than that of models II and IV. The pressure drop of model III is less than that of models I and IV, by (43.67% and 49%). The average percentage error between the theoretical and experimental results was 9.67%.

A precisive calculation method of volumetric and hydraulic efficiency of centrifugal pumps

This paper proposes a new method to calculate the volumetric efficiency and hydraulic efficiency of centrifugal pumps based on the principle of energy balance. Two efficiencies are calculated by means of a low specific speed centrifugal pump handling media with different viscosities at best efficiency points and are compared with those of two existing methods. The results manifest that the definition of two efficiencies in the present paper is more precisive and sensitive to the change of liquid viscosity.

Acoustic absorption by the atmosphere explained by random propagation times

Acoustic and ultrasonic propagation results in a Linear Invariant Filter (LIF). Its complex gain is most often described by a ‘frequency power law’. Equivalently, the complex gain is the characteristic function (c.f.) of a ‘stable probability law’. This strong property justifies a modelization by ‘random propagation times’, which together predict the measured attenuations and obey the principle of energy balance. Except for a Gaussian component, propagation through the atmosphere has no connection with ‘frequency power laws’. In this paper, we show that other components are c.f. of probability laws linked to Poisson and exponential random variables (r.v). Consequently, random propagation times are able to explain propagation losses in the atmosphere.

New solar-biomass assisted thermophotovoltaic system and parametrical analysis

This paper proposes a new technical route of solar-biomass assisted thermophotovoltaic (TPV) system for power generation which uses renewable fuel and contributes to carbon neutrality. Here, a thermophysics model is established for solar-biomass assisted TPV based on energy-balance principle. The effects of some key parameters on the new system performance are investigated, including concentrate ratio, emitter area, biomass fuels, etc. Besides, biomass fuel saving after adding solar energy is investigated. The results show that the solar-biomass assisted TPV system can not only increase the output power of photovoltaic cells by more than 10 kW/m2 compared to biomass-driven TPV but also increase the electrical efficiency by nearly 10 percentage points. It is pointed out that improving the absorptance of solar absorber is the key for system optimization. Furthermore, the annual performance analysis shows that it also saves biomass fuel by up to 60% in one year. This study provides a reference for the design and application of renewable TPV technology.

Analytical and experimental investigation of the mode-II energy release rate of electrodes using a plasticity-assisted zero-degree peeling configuration

Lithium-ion batteries integrate heterogeneous materials such as active layers and current collectors, resulting in interfaces prone to delamination during the charge/discharge process. The mode-II energy release rate is a key index to evaluate the interfacial adhesion properties and structural integrity of electrodes. In this study, an analytical model considering the energy balance principle and a nonlinear constitutive model was established to characterize the mode-II energy release rate. A novel plasticity-assisted zero-degree peeling test (PAZDPT) is proposed to obtain a stable crack propagation stage where the peeling force is determined to calculate the mode-II energy release rate. Several parameter studies were conducted to verify the approximation of the stress distributions and simplification of the analytical model. The accuracy of the analytical model was validated against finite-element calculations. The results demonstrated an excellent agreement between the theoretical calculation and numerical results. Moreover, PAZDPT is conducive to steady crack propagation because it restricts the energy accumulation around the crack tip. The analytical model and newly proposed PAZDPT can also be extended to determine the mode-II energy release rate of other types of interfaces in bilayer thin-film materials.

Estimation of regional actual evapotranspiration based on the improved SEBAL model

The global food and water crises caused by climate warming are becoming increasingly significant. One of the important aspects of surface water transfer is evapotranspiration. The accurate estimation of evapotranspiration (ET) is of great significance in water resource management. However, accurate estimation of large-scale ET is challenging due to the adequate selection of the hot and cold pixels, the heterogeneity of the subsurface and the instability of the lower atmosphere. Therefore, in this paper, a surface energy balance model (Y-SEBAL) was proposed based on the SEBAL model and improved sensible heat flux calculation, and used to simulate large-scale actual evapotranspiration. Based on the principle of surface energy balance, this model introduced the empirical formula of sensible heat flux and simplifies the selection of limit to address the challenge of calculating the sensible heat flux of the crucial variable in the SEBAL model. The study simulated the spatial and temporal evolution of regional evapotranspiration with the model and verified the model simulation performance. In addition, the sensitivity of the model-driven data was quantified. The results showed that the simulation value of the Y-SEBAL model was highly consistent with the eddy covariance measurement data. In the verification results, the R value was 0.82, the index of agreement was 0.90, and the root mean square error was 0.81 mm·d−1. The performance verification indices were better than the SEBAL model, MOD16 model, and SSEBop model. And the model had the highest sensitivity to wind speed, reaching 0.714. The Y-SEBAL model improved the simulation performance of the original model and simulated the actual evapotranspiration. The study can provide a new solution for improving the retrieval of evapotranspiration by remote sensing at the regional scale.

An analytical approach of finding out the equilibrium scour depth at a cylindrical pier when the current is making an angle with the wave

The present work describes the development of a mathematical model for the evaluation of the equilibrium scour depth around a single cylindrical pier under the influence of co-existing waves and current. The presented equation includes the effect of the Keulegan–Carpenter number and Froude number on the formation of scour hole. The principle of energy balance is used to form a nonlinear equation of scour, where the energy of incoming flow when collided with the pier is equated with the weight of the sediments moving away from the vicinity of the pier to establish an equilibrium scour depth. An effort has been made to capture the nature of the flow along x-, y-, and z-directions when the current is inclined at an angle θ with the direction of progress of the wave. Further, the scour profile chosen can incorporate any shape and size of the scour hole. The model has been tested against published experimental data pertaining to two cases, namely when the waves are following the current and when the waves are traveling normal to the current. Here, only linear wave is considered while deriving the equation.

Comparison of two hydro-sediment models based on energy principle of water movement in saturated/unsaturated soils

To study the impact of complex climatic conditions on runoff and sediment, physics-based distributed hydrological models are frequently employed for representation and analysis. In this work, two physics-based hydro-sediment models, namely CASC2D-SED (CASCade 2 Dimensional SEDiment) and GSSHA (Gridded Surface Subsurface Hydrologic Analysis), are used to simulate runoff and sediment in a semi-arid watershed on the Loess Plateau. Examining the degree to which the two models provide comparable or dissimilar outcomes with regard to runoff and sediment casting is an aspect of this investigation that is of utmost importance. Both the models are derived from the principle of mass and energy balance, and arrived at very similar conclusions regarding the infiltration of precipitation and the transport of silt in surface runoff. For typical flood events that occurred between 1981 and 2017, a comparison of modeled data with measured runoff and sediment is carried out. Both models achieved satisfactory results when runoff and sediment simulations were performed over three separate time periods, with average NSE (Nash–Sutcliffe coefficient) values of runoff and sediment are 0.81 and 0.70 respectively. The GSSHA model performs better in terms of the maximum and total amount of runoff and sediment, with an 6.8%, 8.6%, and 6.7% increase, respectively, in the average Rq (relative error of peak flow) Rd (relative error of runoff depth), and Rs (relative error of peak sediment values). In contrast, the CASC2D-SED model simulates better in terms of the Tq (time difference of peak discharge), and Ts (time difference of peak sediment), with the mean time difference of peak flow and sediment values being 0.27 and 1.02 higher, respectively. This shows that the CASC2D-SED model can simulate the timing of runoff and sediment more accurate.

A Microcontroller Based Proportional Integral Derivative Controller for Yam Tuber Storage Chamber Temperature and Humidity Control

Adequate and suitable controlled atmosphere plays an important role in post-harvest yam tuber storage environment for sustaining the quality and quantity of yam tuber especially in a reputable country that produces largest quantities of yam in the world. The effect of post-harvest loss is caused due to lack of appropriate storage systems and these had been the most common problem faced by small-holder yam farmers. In order to avoid post-harvest losses and food wastages due to poor atmospheric condition in West Africa, this paper proposed a microcontroller based Proportional Integral Derivative (PID) controller for controlling the temperature and humidity of yam tuber post-harvest storage. The due technique would maintain a relatively constant temperature and humidity in a storage chamber so as to minimized high level of yam postharvest losses that has become a serious economic and food security threat in West Africa. Some mathematical equations were formulated based on temperature and humidity storage chamber models using heat and energy balance principles. The models were designed using Proteus tools and simulated in Simulink form. The parameters of PID controller were tuned with Ziegler Nichols to achieve a desirable steady state response. The system performances were evaluated in settling time, temperature and humidity set point tracking. The performance metrics were compared with existing technique of Fuzzy Logic Controller (FLC). The sensitivity of the results justified that proposed technique gave a better performance in terms of decreased in settling time, temperature and humidity.

A remote sensing-based method for daily evapotranspiration mapping and partitioning in a poorly gauged basin with arid ecosystems in the Qinghai-Tibet Plateau

Accurate estimation and partitioning of terrestrial evapotranspiration (ET) is essential for understanding the hydrological cycle and water use efficiency at different scales. Such knowledge is particularly important for sustainable water resources management in arid ecosystems. A daily scale framework for continuous ET mapping and partitioning was proposed in this study based on a universal solution of the traditional Ts-VI models. Its essence is to transform the Ts-VI feature space from regional to pixel scale on the basis of surface energy balance principle. Consequently, the ET estimation and partitioning was only related to the boundary conditions at pixel scale, regardless of the Ts-VI configuration over the spatial domain. We demonstrated the framework with MODIS (Moderate Resolution Imaging Spectroradiometer) products in Qaidam Basin, a poorly gauged basin with arid ecosystems in the Qinghai-Tibet Plateau in China. The scheme was performed pixel by pixel using as much of the remote sensing observations as possible, aiming at that it could be applied to other poorly gauged regions. The comparative analysis indicates that our ET estimates agreed well with three readily available ET products and those retrieved from water balance analysis. The advantages of our universal Ts-VI model mainly lie in its high spatial resolution and daily continuity, which enables it to capture the spatial details and temporal variations more accurately. The results show that our annual average ET estimation from 2001 to 2020 was around 179.20 mm/year, which was very close to its annual average precipitation. The annual average soil evaporation (E) and plant transpiration (T) was 168.77 and 10.43 mm/year, accounting for 94 % and 6 % of the total ET, respectively. ET in Qaidam Basin decreased generally from southeast to northwest and from surrounding mountains to the interior with significant vertical zonality. Consequently, ET of different landscapes followed the order: woodland > shrubland > alpine vegetation > alpine meadow > bare rock > alpine grassland > salt crust > desert grassland > bare soil > gobi > sandy land. As an arid basin, the spatial distribution of ET in Qaidam Basin was mainly controlled by precipitation. However, with the further decrease of temperature in high mountains, ET started to be controlled by energy availability rather than water availability. Accordingly, the variations of our ET estimates with altitude increased first and then decreased, with a peak value of 287.67 mm observed at altitudes of 4600–4800 m.

Simplified analytical procedure to calculate the impact behaviour of steel parking-structure columns

The steel supporting frame of automatic mechanical garages is called a parking structure. Presently, for these novel structures, the design codes are without giving detailed guidelines to predict the response of their impacted column. Thus, this paper presents a simplified analytical procedure to calculate the impact behaviour of the column. The proposed method is based on the co-rotational rigid body model and follows the energy-balance principle. Compared with the previous analytical method, it specially targets the parking-structure column and can be used to conveniently and quickly calculate the column transverse displacement with considering the effects of the surrounding structural members and axial loads on the column. The research covers the situation where the column is subjected to the impacts at a low velocity, critical velocity, and overcritical velocity. Primarily, an approach is developed to simplify the overall parking structures. On that basis, the calculation formula for the critical impact velocity, i.e. the velocity that results in the formation of plastic hinges in the column, is derived. To predict the behaviour of the column under the impact beyond the critical impact velocity, the simplified analytical procedure is provided and then its accuracy is examined by validated numerical models. Eventually, according to the procedure, some suggestions are given to improve the design of the column after parametric analyses. It is recommended that control the axial-load levels of the column, particularly the column with a small section area, as well as set stiffeners on the column within the height of 1000 – 1500 mm.

Numerical modelling of coal and gas outburst initiation using energy balance principles

Coal and gas outburst is a common mining hazard as it cannot be readily predicted due to complex processes controlling its occurrence. Understanding these complex processes such as gas flow, mechanical properties and behaviour, stress regimes, and geological structures, is required to enable mitigating the outbursts. The most current thresholds proposed for outburst prediction are empirically based thus ignoring the physical processes involved. While numerical modelling is a powerful tool to simulate the involved physical mechanism in coal and gas outbursts, the use of thresholds for outburst initiation in numerical models has not attracted enough attention to date. In this study, the law of conservation of energy is used to determine the moment of the outburst occurrence; the energy of which is obtained through numerical simulation. Different sources of energy including elastic energy and, free and desorbed gas energies linked to the complex physical processes are modelled and discussed. Different mechanical properties of coal are assigned to discuss the distinction of energy values between normal coal and coal affected by geological structures (known as deformed coal). A 30 m long roadway excavation that penetrates through both normal and deformed coals is simulated to assess the effect of induced stress on outburst initiation during roadway development. In addition, the effects of initial gas pressure and damaged area on the propensity of outburst events are analysed. The numerical model can successfully simulate gas outbursts caused by deformed coal, which poses a higher outburst risk. In addition, the modelling results demonstrate that by increasing the gas pressure in the coal seam, outburst happens in the earlier stages of the roadway development, and more intense outburst can be expected.

Resolving systems of ordinary differential equations in a naphtha reforming process: Comparison of laplace transform and numerical methods

Developing a simple technique to generate important hydrocarbon products as raw feed materials would benefit the petrochemical industry. This paper presents the Laplace transform method in comparison with the numerical method of resolving systems of ordinary differential equations in a reforming process in a tubular reactor for the production of essential hydrocarbon components as petrochemical feedstocks. The feed species, lumped naphtha (paraffin), was fed into the tubular reactor for reforming (cracking) into essential hydrocarbon components including naphthenes, aromatics, and gases (methane, ethane, propane, and butane). Material and energy balance principles were applied to obtain nonlinear reactor models as a function of mole fractions and temperature. Laplace transform was then used to resolve the nonlinear reactor models into algebraic forms to describe the transformations in the depleting species and the formation of the target products in the reactor. Real plant (industrial) data were further used to simulate the models while literature data were used for model comparison. The comparison of the models was based on numerical and analytical results obtained for the mole fractions and temperature. With the analytical method as a reference, results showed that the numerically simulated results deviated from the analytical results by 0.10, 1.93, 16.09, 22.34, and 4.511% for paraffin, naphthene, aromatics, gases, and temperature, respectively; all within the recommended values for reactor cracking operations. This suggests that the analytical approach yielded better results than the numerical method.

Trapezoid-based surface soil moisture retrieval using a pixel-to-pixel scheme: A preliminary result over the North China Plain

• A pixel-to-pixel scheme of the trapezoid-based methods has been developed. • Satellite data was used to obtain atmospheric variables required by the trapezoid. • Estimated surface soil moisture were evaluated with in-situ and microwave data. The trapezoid configuration constituted by spatially distributed land surface temperature (LST) and fraction vegetation cover (FVC) has been widely used for estimating surface soil moisture (SSM) with satellite data. However, the trapezoid-based methods still suffer from a major challenge that the determination of the trapezoid pixel window is always subjective, because it requires quasi-identical atmospheric conditions to make SSM retrievals for each pixel spatially comparable. Meanwhile, the trapezoid pixel window should also contain full vegetation coverages and SSM dynamics to fulfill the inscape of the trapezoid. Due to the heterogeneity of atmospheric variables and underlying surfaces, it is commonly difficult to determine a proper trapezoid pixel window in practices. The development of the pixel-to-pixel scheme of the trapezoid aims to decrease the dependence of trapezoid-based SSM retrieval on the subjective requirements of quasi-identical atmospheric conditions, full vegetation coverages and SSM dynamics. In the present study, for each pixel over the North China Plain, a unique virtual trapezoid was created and the theoretical boundaries were determined following the principle of surface energy balance where satellite-derived essential atmospheric variables of air temperature, net surface shortwave radiation and relative humidity were provided as inputs. Based on the proposed approach, a daily/5-km SSM dataset during the growing season from April to October in 2016 was produced over the North China Plain. A preliminary evaluation reveals an overall acceptable accuracy of the estimated SSM with root mean square error of ∼ 0.06 m 3 /m 3 and ∼ 0.08 m 3 /m 3 when comparing to in-situ measurements and microwave SSM product, respectively.

A plastic design method based on multi-objective performance for high-strength steel composite K-shaped eccentrically braced frame

A plastic design method based on multi-objective performance (PDMP) for high-strength steel composite K-shaped eccentrically braced frame (HSS-KEBF) is developed in this study, which explicitly considers the different seismic fortification objectives of the structure and the shear distribution relationships of the brace-frame system. The performance objectives of the structure under three seismic hazard levels were obtained by combining different roof drift ratios and displacement ductility demands, and a trilinear capacity curve of HSS-KEBF considering the change of post-yield stiffness was proposed. The energy balance principle was used to calculate the elastic and elastic–plastic shear distributions of the brace-frame system under different performance objectives, to facilitate the elastic–plastic design of HSS-KEBF. A ten-story HSS-KEBF structure was designed using the proposed design method, and an elastic-plastic finite element model of the structure was established using OpenSees for analysis. The results show that the structural model achieves the expected performance objectives in terms of capacity curves, roof drift ratios, base shears, and failure modes. From the SLE level to MCE level, the base shear distribution ratio borne by the frame component increased from 36% to 46%, which satisfies the design idea of multi-aspect fortification.