Proposed Finite Element Model Research Articles

Parametric Study of PEKK Based Fiber Metal Laminates Used in Aerospace Applications

Numerical analyses offer a cost-effective and efficient alternative to experimental investigations, and Finite Element (FE) models have become a popular tool to simulate the behavior of Fiber metal laminates (FMLs) under impact loads. This study verified the reliability of the proposed FE models to predict the perforation response of ‎the FMLs investigated under low-velocity impact loadings. The validation of ‎the FE models was assessed through comparison with the corresponding results of the ‎experimental work. The results showed that the proposed simulations are capable of predicting the dynamic response of the laminates investigated with a high degree of success. The parametric studies were conducted on 2/1 titanium FMLs based on 2-ply composite cores and 2/1 aluminum FMLs based on 4-ply composite cores under impact with a variety of loading conditions. The developed FE models were then used to explore the structural behavior of the fiber metal laminates investigated with an extended variation of parameters, i.e., projectile striking angle, impact locations, the geometry of the projectile, and velocity. The results of the FE models are presented in terms of load-displacement traces, energy absorption, and failure modes. The findings of this study contribute to the understanding of the structural behavior of FMLs under impact loads and can inform the design and optimization of FMLs for various engineering applications. The use of FE models provides a cost-effective and efficient means of exploring the structural behavior of FMLs under different impact conditions, which can reduce the need for costly and time-consuming experimental investigations.

Computational modeling and simulations for predicting the nonlinear responses of reinforced concrete beams

PurposeThe ultimate capacity and ductility behavior of a reinforced concrete (RC) beam generally depends on its constituent material properties. This study aims to use ANSYS to accentuate the nonlinear parametric finite element (FE) simulations of RC sections under monotonic loading.Design/methodology/approachThe concrete matrix and steel reinforcement are the primary constituent materials of RC beams. The material properties such as tensile reinforcement area, tensile bars yield strength, concrete compressive strength and strain rate in tensile reinforcement at nominal strength have significantly influenced the ultimate response of RC beams. Therefore, these intensive parameters are considered in this study to ascertain their effect on the RC beam's ultimate behavior. The nonlinear response up to the ultimate load capacity and the crack evolutions of RC beams are predicted efficiently.FindingsThe parametric study reveals that increasing the tensile steel reinforcements (from Ast = 213–857 mm2) significantly improves the ultimate load capacity by 229% and yield deflections by 20%. However, it declines the ultimate deflection by 47% and ductility by 56% substantially. Varying the strain limit (?tn = 0.010–0.0015) of tensile reinforcement has proficiently increased the ultimate load-resisting capacity by 20%, whereas the ductility declined by 62%. When the concrete strength increases (from fck = 25–65 MPa), the cracking load increases profoundly by 51%, whereas the ultimate capacity has found an insignificant effect.Originality/valueThe load-deflection response plots extracted from the proposed numerical model exhibit satisfactory accuracy (less than 9% deviation) against the experimental curves available in the literature, which emphasizes the proficiency of the proposed FE model.

Numerical and Experimental Behavior Analysis of Slabs Strengthened Using Steel Plates and Slurry-Infiltrated Mat Concrete (SIMCON) Laminates

This study has two main aims; firstly, investigating the behavior of slabs that are strengthened with different types of reinforcements and with Slurry-Infiltrated Mat Concrete (SIMCON) laminates, having different dimensions and thicknesses and subjected to static and dynamic (impact) loads. Secondly, the development of a non-linear finite element (FE) model to simulate the behavior of the tested slabs utilizing the ABAQUS/Standard package. The modeling of the NSC slabs strengthened with either SIMCON or steel plates involves using three-dimensional solid elements that are partially integrated with the modeling of concretes using the 8-node brick element (C3D8R). The results of the experimental and numerical investigations are compared to examine whether the slab modeling is sufficient. The comparison includes the element type, material characteristics, real constants, and convergence study. The predicted ultimate load-carrying capacity versus vertical deformation response is compared with the lab results that correspond with it, as obtained via the FE analysis of all tested slabs. In addition, the results of the FE analysis of slab specimens that are strengthened with steel plates were compared to the results of the ones strengthened using SIMCON laminates. The obtained results have led to a number of significant observations. Considering the punching shear strength, it was found that using SIMCON strengthening in different dimensions increased the slab’s punching shear capacity and outperformed steel-strengthened slabs. As for the plate stiffness, SIMCON-strengthened slabs presented higher stiffness rates than steel-strengthened slabs, to the extent that even 20 mm SIMCON strengthening outperformed the steel plate-strengthened slabs of any thickness or dimensions. The axial load-displacement relationships indicate that all the numerical models show a stiffer behavior when compared with the experimental axial load-displacement relationships. The slab thickness of SIMCON significantly affects the load-carrying capacity, and it increases with the increase in thickness. Likewise, using strengthening from steel plates gives a higher load-carrying capacity. Finally, since the results of the yield line analyses for these slabs are found to match the experimental results closely, this method is considered to be suitable for practical use in determining the strength of plated slabs. Therefore, the conclusion is drawn that the proposed FE model can be sufficiently used in evaluating the dynamic responses of slabs strengthened with SIMCON or steel plates and subjected to cyclic and impact load.

Finite Element Modeling of Interface Behavior between Normal Concrete and Ultra-High Performance Fiber-Reinforced Concrete

The behavior at the interface between normal strength concrete (NSC) and Ultra-High Performance Fiber-Reinforced Concrete (UHPFRC) plays a crucial role in accurately predicting the capacity of UHPFRC for strengthening and repairing concrete structures. Until now, there has been a lack of sufficient finite element (FE) models for accurately predicting the behavior at the interface between NSC and UHPFRC. This study aims to investigate the structural behavior of composite members made of NSC and UHPFRC by developing a model that accurately simulates the interface between the two materials using a linear traction-separation law. Novel parameters for the surface-based cohesive model, based on the traction-separation model, were obtained and calibrated from prior experiments using analytical methods. These parameters were then integrated into seven FE models to simulate the behavior at the interface between NSC and UHPFRC in shear, tensile, and flexural tests. The accuracy of the FE models was validated using experimental data. The findings revealed that the proposed FE models could effectively predict the structural behavior of composite NSC-UHPFRC members under various working conditions. Specifically, the maximum deviations between EXP and FEA were 6.8% in ultimate load for the shear test and 15.9% and 2.8% in ultimate displacement for the tensile and flexural tests, respectively. The model can be utilized to design the use of UHPFRC and ultra-high performance fiber-reinforced shotcrete (UHPFRS) for repairing and strengthening damaged concrete structures.

FE-assisted investigation for mechanical behaviour of connections in offshore wind turbine towers

The overall competitiveness of offshore wind turbine towers is significantly influenced by the selection of the connection. The following three types of connections: a conventional bolted ring flange (RF) connection, ring flange connection with defined contact surfaces (RFD), and C1 wedge connection (C1-WC) are considered. A quantitative comparison is made to enhance performance in a specific condition and enable further optimization of these connections in engineering practices. The study compares the tensile behaviour and fatigue performance of these connections by validated finite element (FE) simulation and analysis. The proposed FE modelling is based on a realistic geometry including all contacts present in the connections, steel full-range stress–strain relationship and ductile damage model. The efficiency and accuracy of the FE models are validated through the comparison with the performed tests. Then, a series of parametric FE analyses are carried out to examine the impact of the applied boundary conditions, bolt pretension level, and steel grade on the behaviour of connections. Load-displacement curves, bolt evolution curves, and stress responses are analysed to compare their tensile behaviour. The effectiveness of conventional segment specimen testing is evaluated thoroughly. For the fatigue performance of connections, the results indicate that the segment specimen testing substantially underestimates the fatigue performance of C1-WCs. This discrepancy is essential to be considered in the tower design. It is also noted that C1-WCs are rather insensitive to the variation of pretension force level, which show superiority to avoiding the difficulties associated with typically bolted joints. This research provides in-depth knowledge for the practical application of such connections and further optimization.

Seismic Performance of Self-Centering Square Concrete-Filled Steel Tubular Column-to-Steel Beam Connection under Variable Axial Force

A self-centering square concrete-filled steel tubular column-to-steel beam connection with bolted angles was designed and its behavior analyzed theoretically. Three ½-scale specimens differing only in the loading procedure of the vertical force were tested under cyclic loading conditions. A finite element (FE) model of the self-centering connection was established in the ABAQUS software and its validity verified against experimental results. Compared with experiments, an extended parameter analysis of the variable axial force with a wider variation range of axial force and variable axial force in imitation ground motion was conducted using the proposed FE model. The experimental results showed that specimens with larger axial forces and variable axial forces consumed more energy and had clearer residual drifts compared with those of specimens with smaller axial forces and constant axial forces, respectively. The simulation results showed that a larger axial force considerably decreased the resistance capacity of the lateral load, resulting in a descending skeleton curve. A clear residual drift and asymmetry in the maximum relative rotation were observed under positive and negative displacement upon increasing the axial forces. In addition, a larger range of change in the axial force resulted in a more prominent residual drift compared with a smaller range of change in the axial force under a relatively small lateral displacement, decreasing the reliability of the self-centering capacity of the connection during an earthquake.

Flexural strengthening of reinforced concrete beams using hybrid fibre reinforced engineered cementitious composite

In this study, flexural strengthening of reinforced concrete (RC) beams using steel and polyvinyl-alcohol hybrid fibre reinforced engineered cementitious composite (SPH-ECC) with embedded steel reinforcement bars is proposed. The effectiveness of the strengthening was investigated by experimental and numerical studies. The flexural behaviours of one unstrengthened 3500 mm long, 200 mm wide, and 325 mm deep RC beam and three RC beams strengthened with different configurations of 50 mm thick SPH-ECC layer(s) were studied by conducting four-point bending tests. Detailed flexural behaviours in terms of peak load, failure mode, load-deflection curve, cracking patterns, interfacial bond-slip, strain distribution and ductility of the tested beams were studied and compared. Experimental results showed that both the flexural strength of strengthened beams, which were in the range of 125% to 210% of the unstrengthened control beam, and the interfacial bond-slip behaviours between concrete and SPH-ECC was highly depended to the strengthening configuration used. Crack width control ability of the beams was also improved by using SPH-ECC. A finite element (FE) procedure using surface-to-surface cohesive model was also developed to model the flexural behaviours of the strengthened beams. Comparison with experimental results demonstrated that the proposed FE model could accurately predict the flexural behaviours including interfacial bond-slip between the SPH-ECC layers and the RC beam part of the strengthened beams.

Dynamic Stress Analysis of Multisegment Curved Pipes Subjected to the Passage of an In-Line Inspection Tool

AbstractPipelines are susceptible to degradation over time due to different types of defects caused by environmental and loading conditions. In-line inspection (ILI) is a preventive examination method widely used to monitor the degradation of pipelines. The passage of an ILI tool through a segment of a pipeline with loose boundary condition can generate significant dynamic stress within the pipe. When pipelines pass through excavated sites, bridges, water, and bog, or have free-span segments, they are at a greater risk of dynamic stress. This research aims to study the effects of passing an ILI tool through pipelines consisting of straight and curved segments. A three-dimensionial finite element (FE) model based on the Timoshenko beam theory is developed to model the vibration response of curved pipes during the passage of an ILI tool. Lab-scale experiments are performed to verify the simulation results of the developed FE model. The developed model is further verified through the FE analysis performed in abaqus™ implicit. A comparison of the simulation and experimental results shows that the proposed FE model effectively and accurately predicts the dynamic stress and dynamic displacements of multisegment pipes during the passage of an ILI tool.

Finite-Element Modeling for Seismic Damage Estimation of Suspended Ceiling Systems

The seismic qualification and seismic performance assessment of suspended ceiling systems have been traditionally conducted through large-scale shake table testing. This experimentally-based approach not only involves significant financial and time resources but is also not flexible to evaluate several configurations of suspended ceiling systems. As an alternate approach, this paper discusses the development of a general finite-element (FE) model of suspended ceiling systems that accurately captures the propagation of damage observed during full-scale shake table testing using the commercial finite-element analysis software, Abaqus/Explicit. The results of the large-scale shake table testing on suspended ceiling systems conducted at the University at Buffalo as part of the NEES nonstructural project were used to validate the FE model. The major components of suspended ceiling systems such as grid runners, ceiling tiles, and hanger wires were modeled and assembled with significant detail in the FE model. The properties of the connections between the grid runners, which are vital for capturing the seismic behavior of suspended ceiling systems were derived numerically. A user-defined subroutine was incorporated in the Abaqus/Explicit software framework to capture the multidirectional pinched hysteretic behavior of the connections between grid runners. An illustrative example of the application of the proposed FE model to develop robust numerically generated fragility curves for suspended ceiling systems is presented.

Structural performance evaluation of airport asphalt pavement based on field data measurement and finite element simulation

Airport asphalt pavement failure is caused by the combined effects of temperature and aircraft loading. Sensors have been effectively used to monitor the structural health of airport asphalt pavements. However, deploying sensors in multiple locations results in limited and discontinuous information. In this sense, finite element (FE) models are established to analyze the pavement service conditions at arbitrary locations in the airport pavement. First, sensors are used to measure pavement response and temperature data to verify the feasibility of the finite element method (FEM). Secondly, temperature index and performance-based zones of pavement structural layers are proposed based on the FEM. The proposed FE models demonstrate the feasibility of obtaining structural response and temperature distribution for performance zoning of different structural layers. This method improves the accuracy of performance evaluation through field data measurements, and provides guidance for the optimal design of airport pavement structure.

Study on Machining Quality of Aluminum Honeycomb in Ultrasonic Cutting by Disc Cutter

Abstract Aluminum honeycomb has been highlighted in aeronautics and astronautics in the form of the sandwich structure, but defects are easily generated during machining. Ultrasonic cutting for honeycomb material has received growing attention over the past years for improved machining quality and efficiency. In order to support the industrial application of the ultrasonic cutting for aluminum honeycomb by disc cutter, a finite element (FE) model is established and experimental investigations are conducted to study the influencing factors of the machining quality. The proposed FE model is verified by the comparison of cutting forces obtained from simulations and experiments. Based on the FE model and experiments, influences of tool orientation precisions, including lead angle and runout of disc cutter, are analyzed first. Moreover, cutting force, honeycomb morphology, the stress in the cutting zone, and cell wall deformation at different cutting parameters are investigated. Results show that the lead angle should be set as a slightly positive value, and the axial runout of the disc cutter should be controlled to an extremely small value to avoid machining defects. Meanwhile, the cutting forces decrease significantly with the application of the ultrasonic vibration and increase with the increases in the feed speed and the cutting depth. Therefore, a well-machined surface can be obtained by applying ultrasonic vibration, cutting at a lower feed speed, and a smaller cutting depth.

Fiber pull-out in a flexoelectric material

This work examines the fiber pull-out problem in the context of flexoelectricity. As a first approach we examine the deformation of an infinitely long prism due to the action of a concentrated out-of-plane line force. We assume that the material of the prism responds in the context of flexoelectricity and anti-plane conditions prevail. We incorporate the approach proposed by Giannakopoulos and Zisis [1] according to which the gradient of the polarization is incorporated into the strain energy density function. Accordingly, the field equations decouple in terms of the primary variables of the problem, that is the out-of-plane displacement and the polarization. The concentrated out-of-plane line force is materialized in the form of an out-of-plane body force. For the proposed problem we develop analytical solutions with respect to the out-of-plane displacement and polarization under static and dynamic conditions. Next, we propose a finite element (FE) model based on a structural plate analogue, for the solution of anti-plane flexoelectric boundary value problems. The proposed FE model is applied to the predefined problem and the numerical and the analytical results regarding the out-of-plane displacement are compared and found to be in excellent agreement. Next, we propose yet another structural analogue (membrane analogue) for the numerical treatment of the polarization equation and again the results are compared with the analytical solutions with respect to the polarization of the predefined problem and excellent agreement is attained. Finally, for the predefined problem the electromagnetic response is investigated and analytical solutions are proposed.

Electromagnetic transient model and field-circuit coupling numerical calculation of Sen transformer based on finite-element method

• A finite-element (FE) model of electromagnetic transient of Sen transformer (ST) with field-circuit coupling is proposed, and the proposed model can characterize the effects of core and winding topology on the internal magnetic field distribution. • The proposed FE model can characterize the electromagnetic field changes of the ST device under different conditions, such as short-circuit fault, injected harmonics, and dynamic power flow control in the external power system. • The electromagnetic transient field-circuit co-simulation of the ST device and external power system is realized. The conventional electromagnetic transient model of Sen transformer (ST) is mainly established by the magnetic equivalent circuit method, which can be used for the fast calculation of transient characteristics for ST. Unfortunately, this approach may lead to oversimplification and missing significant information in the modeling process. To accurately calculate the transient electromagnetic field and reveal the internal magnetic field distribution of the ST under different operating conditions, an electromagnetic transient model and field-circuit coupling numerical calculation of ST based on finite-element (FE) method is proposed in this paper. The proposed model can characterize the effects of core and winding topology on the internal magnetic field distribution, as well as the complex nonlinear property of core materials, such as saturation, eddy current, and hysteresis. The field-circuit coupling method enables the FE model to establish a connection with external networks and realize the electromagnetic transient field-circuit co-simulation of the ST device and external power system. The case studies are performed on a FE model of the ST and a two-machine transmission system. The corresponding winding voltage and current variations of the ST in the presence of short-circuit fault, injected harmonics, and dynamic power flow control in the external networks are analyzed. The numerical calculation and co-simulation results of the proposed FE model of the ST and the external networks are compared with the commercial FE software, which demonstrates the effectiveness of the proposed FE model of the ST. Moreover, the co-simulation results of dynamic power flow control show that the ST can adjust the power flow distribution of two transmission lines through changing compensation voltage.

A quasi-static biomechanical model of the human myocardium based on Cardiac Magnetic Resonance images

The left ventricle (LV) has an important mechanical part in pumping blood throughout the body and it is generally sensitive to the failure. Heart failure is one of the world's leading causes of death and has reached the epidemic rate. For the study of heart failure, there are several diagnostic methods, but computational biomechanical models of human myocardium would be a practical tool in diagnostics and patient specific treatment planning. These models help in classifying myocardium pathologies. In this paper, we developed a quasi-static biomechanical model of the LV for healthy subjects based on Cardiac Magnetic Resonance (CMR) acquisition. Estimation LV strain is done using Finite Element (FE) software Abaqus and clinical assessment measured from 20 healthy subjects, such as End Systole (ES) and End Diastole (ED) volumes, ED wall thickness and wall thickening. We acquired LV End Systole strain component is within one standard deviation of the measurements made in the equatorial region of LV. The results of this study suggest that the proposed FE model of LV describes the physiological function of the heart and can differentiate between normal and pathological cardiac function.

Finite element and analytical modelling of PVC-confined concrete columns under axial compression

Confined concrete in pipes provides a solution for the structures to resist lateral forces and avoids the problems associated with production of confined concrete and lateral reinforcement. To evaluate the influence of PVC pipe on the compressive behavior of concrete filled composite tubes, ABAQUS software was used to simulate 44 concrete filled PVC pipes (CFPT). The influence of internal steel reinforcement, unconfined concrete strength, slenderness ratio, specimen’s size and thickness of PVC tube on failure mode load carrying capacity, and strain of PVC confined reinforced concrete column was studied. The present discussion show that the existing analytical models failed to capture the effect of these parameters. On the other hand, the proposed finite element (FE) models achieve a very good agreement between the experimental and analytical values. The proposed FE model can provide an acceptable portrayal of the CFPT’s response. The response of confined concrete was estimated using trial and error approach and as a result a model for the strain of confined concrete was proposed. The effect of these parameters on the CFPT leads to development of analytical models.

Vibration Analysis of Bistable Unsymmetric Laminates with Curvilinear Fiber Paths

Multistable laminates have been actively studied in recent years due to its potential applications in morphing and energy harvesting devices. Variable stiffness (VS) bistable laminates provide opportunities for further improvements in design space in comparison with constant stiffness bistable laminates. The snap-through process involving shape transition between the stable configurations is highly nonlinear in nature and exhibits rich dynamics. Exploiting the dynamic characteristics during the snap-through transition is of considerable interest in designing the morphing structural components. In this paper, we present a semi-analytical model based on Rayleigh–Ritz approach in conjunction with Hamilton’s principle to predict the natural frequencies of bistable VS laminates. The obtained results are compared with the results from the full geometrically nonlinear finite element (FE) model. The proposed FE model is further extended to study the dynamics of VS laminates subjected to external forces with different amplitudes. Subsequently, a parametric study is performed to explore the effect of different curvilinear fiber alignments on natural frequencies, mode shapes, free vibration characteristics and forced vibration characteristics (single-well and cross-well vibrations).

Prediction on aeroengine blade foreign object damage validated by air gun tests

Aeroengine in service was prone to ingest foreign objects, leading to foreign object damage (FOD) and failure accidents of the blades. In this paper, laboratory FOD tests were firstly conducted on TC4 and AM355 steel simulated airfoil specimens impacted by 3 mm diameter projectile at a speed of 350 m/s, and numerically reproduced using Johnson-Cook (J-C) model with failure criterion. A penetrating-type notch (P-notch) with severe material loss was observed, and a good agreement between experiments and finite element (FE) predictions could be found for both notch morphology and size. The influence of impact velocity on FOD and the FOD-induced residual stress were investigated by the proposed FE model. High tensile stress was observed along the notch edge, while the bottom of notch was mainly dominated by compressive stress. Finally, a FE model of aeroengine blade considering the initial centrifugal force was developed, and the influences of FOD to compressor blade on its modal properties were discussed. Compared to the normal blade, the damage induced a deviation in frequency within 1 %.

Thermal performance of cross-laminated timber (CLT) and cross-laminated bamboo and timber (CLBT) panels

ABSTRACT Cross-laminated timber (CLT) is increasingly being utilized in Europe, North America and elsewhere due to its superior mechanical properties and environmental-friendly performance. Considering regions and countries, such as China, those are scarce in structural wood resource but rich in bamboo forest, an idea of introducing bamboo into CLT system has been proposed to form a novel composite material, named as cross-laminated bamboo and timber (CLBT). This paper focuses on the comparison of thermal insulation performance of CLBT and CLT panels. The thermal resistance and transmittance of CLT and CLBT wall specimens were measured by the Guarded Hot Box test. A calculation method provided by ISO standard and a finite element (FE) model were also used to evaluate the thermal resistance of CLT and CLBT panels. Based on the proposed FE model, some parametric analysis was performed through 11 CLBT panels with different compositions, including the layer number of glubam and timber, the thickness of extruded polystyrene and the use of gypsum board and screws. Moreover, the feasibilities of these CLBT panels were evaluated for the application in different climate regions of China and the United States in accordance with the corresponding Chinese and American building energy efficiency standards, respectively. It can be finally concluded that, the development and application of CLBT contributes to achieving the low carbon sustainable features of structures, which is due to the good carbon sequestration ability of its component materials (i.e., timber and bamboo) as well as the good insulation performance of CLBT panels.

Analysis of CFRP-confined CFST columns reinforced with steel angles under axial compression

To study the axial compression properties of specimens of concrete-filled steel tubes reinforced with steel angles, abbreviated as SRCFST, and of specimens of FRP-confined SRCFST, abbreviated as F-SRCFST, relevant finite element (FE) models were established using ABAQUS software. For verifying the accuracy of the proposed FE models, the axial load carried by each component of the specimen was first analysed and the distribution rules of the contact pressure between the steel tube and concrete as well as between the steel angles and concrete were analysed. In the second phase, the important parameters, such as the yield strength and wall thickness of the steel tube, the yield strength and cross-sectional area of the steel angles, the tensile strength and number of FRP wrapping layers were analysed. The third phase consisted of creating and proposing the design formulas for the SRCFST and F-SRCFST specimens on the basis of parametric analyses and numerical fitting method. The research results indicate that FRP has a minimal effect on the axial carrying capacity of the steel tube and the fundamental effect for the improved ultimate load is the indirect confinement effect by the FRP on the concrete. The proposed design formulas can accurately predict the ultimate load of SRCFST and F-SRCFST specimens, and the calculation error is generally within 10%.

Seismic Performance and Finite Element Analysis of Reinforced Concrete Frames Considering a Masonry-Infilled Wall

This study investigated the seismic performance of a 1/3 scale, three-story, and three-span RC frame subjected to static cyclic lateral loading. The failure process and mode were analyzed using the digital image correlation (DIC) method. Based on the test, finite element (FE) models were developed and verified. Using the proposed FE models, the parametric study was performed to investigate the influence of the opening rate, the position of infill walls, and the block strength on the seismic performance of the frame. Test results indicated that FE simulation results are correspondent to the testing results. The infilled wall increased the horizontal bearing capacity of the structure and the energy dissipation capacity. The opening masonry-infilled wall reduced the energy consumption capacity and the initial stiffness of the structure. Removing the infill walls on the first floor would change the failure mode of the frame. Improving the block strength could improve the bearing capacity of frames but has little effect on the energy dissipation capacity of the frame.