Thick Steel Plates Research Articles

Fiber–Based Model for Simulating Inelastic Interaction Buckling of Rectangular CFST Slender Columns with Unequal Wall Thickness

Rectangular concrete-filled steel tubular (RCFST) columns can be designed to have unequal wall thickness to maximize their resistance to combined axial and uniaxial bending loads. However, there is very little published research on their local–global interaction buckling behavior. This paper presents an efficient fiber-based simulation model for analyzing the inelastic interaction buckling of eccentrically loaded RCFST slender columns with unequal wall thickness. The model considers the progressive local–global interaction buckling, distributed plasticity, concrete cracking and crushing, second-order effects, and geometric imperfections. The mathematical model is programmed to compute not only the axial load–displacement responses but also the interaction curves of axial load and moment of slender RCFST columns. The simulation modeling is validated by experimentally measured data. The validated computer model is used to parametrically study the interaction local–global buckling responses of RCFST columns while the range analysis is conducted to identify the relative significance of key parameters. It is demonstrated that the proposed computer model accurately simulates experimentally measured responses. Hence, it can be used with confidence in practice to analyze and design RCFST slender columns fabricated with steel plates of unequal thickness. The existing design standard AS/NZS 2327:2017 provides acceptable strength predictions of RCFST slender columns and beam-columns while the procedure specified in Eurocode 4 overestimates their capacities.

Mechanical properties and constitutive model of Q345GJ thick steel plate in China

The Q345GJ steel plate is a common Chinese product that has an increasingly wide usage in civil engineering. However, previous research on Q345GJ steel plates with thicknesses of no less than 60 mm is limited, especially the systematic cyclic loading tests, causing an inadequate understanding of the cyclic behaviour and corresponding constitutive parameters of thick steel plates. To further investigate the mechanical property of Q345GJ thick steel plates and fill the gap of test databases, layered specimens obtained from five different thickness positions of the 60-mm and 100-mm thick Q345GJ steel plates were tested under monotonic tension and five cyclic loading protocols. The mechanical properties of specimens in different thickness positions were compared and analysed. Moreover, parameters of the Chaboche cyclic constitutive model were calibrated and then validated by finite element analysis (FEA). Results indicated that the surface-layer specimens exhibited greater strength and lower ductility than the middle-layer specimens. Furthermore, the hysteretic curves of all the specimens were plump, where the energy dissipation of the surface-layer specimens was greater than that of the middle layer, particularly for the 100-mm thick plate. Based on the test results and calibrated parameters of the Chaboche constitutive model, significant isotropic softening characteristics were observed for all thickness positions. Following the tests and analysis, the cyclic constitutive model calibrated in this study was verified to support further numerical simulations.

Performance of steel–concrete composite walls with recycled aggregate concrete under low-velocity lateral impact loading

This paper investigates the impact-resistant behaviours of steel–concrete (SC) composite walls experimentally and numerically, which consist of two outer steel plates and infilled recycled aggregate concrete (RAC). Totally eight SC walls were designed and fabricated with different coarse recycled aggregate (CRA) content and steel plate thicknesses. Drop-hammer impact testing was first performed to obtain the failure mode, impact force and deformation. Test results indicated that the impact resistance behaviour of SC walls enhanced considerably with a decrease in CRA content. The tie bars combined with studs were effective to avoid the separation of steel plate from the concrete core. Afterwards, the finite element (FE) models were developed and calibrated, and then used to obtain more information on the full-range motion response, development of stress and strain, and energy absorption. In addition, the influences of different parameters, including the CRA content, material strength, steel plate ratio, tie-bar spacing, impact energy and axial load ratio on the impact resistance performance were assessed. Finally, the displacement response of SC composite walls with RAC was predicted using single-degree of freedom (SDOF) approach.

Lateral enhancement effect of reactive PELE: Two-step segmented simulation and analytical modeling

Comparing with traditional PELE, the reactive PELE shows a more significant lateral enhancement effect due to the deflagration reaction of the filling by impact. Here an analytical model for thin-walled jacket fragmentation and dispersion is presented based on the wave interaction and the reaction of reactive filling. Subsequently, a two-step segmented numerical simulation for the impact deflagration of reactive PELE is developed. Based on the numerical simulation, the wave interaction process and the internal stress distribution of the filling were given firstly, then the deflagration reaction of reactive filling, jacket fragmentation and dispersion were simulated. By the theory and simulation, the experiment results of reactive PELE impacting steel plate are analyzed. In the experiment, the thickness of the front steel target is 6mm-20 mm, and the multi-layer witness aluminum plate is set behind the steel target to obtain the lateral effect of the reactive PELE. The analysis results show that the released energy of the reactive filling increases the maximum radial velocity of the jacket fragments by more than 40 %, and the perforation dispersion on the witness plate significantly depends on the filling reaction level and the front steel plate thickness, the lateral enhancement mechanism of reactive PELE impacting plate is explained.

Damage modes and mechanism of steel-concrete composite bridge slabs under contact explosion

The steel-concrete (SC) composite bridge slab is widely used in long-span bridges. With the increasing threat of explosive attacks on bridges, understanding the blast-resistant performance of composite bridge slabs is important. In this paper, SC composite slabs with different types of interfaces between concrete slab and steel plate, and different steel plate thickness, were tested under contact explosion. The damage modes and dynamic responses were carefully observed and measured. Refined FE models were developed to investigate the damage mechanism by analyzing and comparing the detailed damage process of slabs and characteristics of stress wave propagation. The results revealed that the damage modes of SC composite slabs varied significantly depending on the type of interface. For slabs with stud connectors, the compressive stress wave propagated within the composite slab in a spherical pattern and finally induced a circular concrete crater and steel plate deformation. Increasing the thickness of steel plate significantly reduced steel plate deformation. For slab with PBL connectors, the stress wave in the concrete was attenuated when it propagated across the PBL ribs, while the stress of concrete between the ribs nearest to the explosion was much large than that outside the ribs. Stress reflection on the top of PBL ribs increased the damage degree of concrete, potentially leading to induced cracks along the ribs. The overall response of composite slabs could be divided into the combined phase and separated phase. The PBL ribs could better restrain the interface detachment compared to studs.

Experimental study and numerical simulation on shear behavior of steel and concrete composite beam with molybdenum tailing

To improve the flexural performance of steel–concrete composite beams and alleviate the problem of sand depletion caused by the application of concrete structures, this paper proposes a new type of steel-molybdenum tailings concrete composite beam. In order to further study the shear performance of the new type of steel-molybdenum tailings concrete composite beam, this paper couples molybdenum tailings replacement ratio (0%, 50%, and 100%) and shear span ratio (1 and 2) as research parameters, designs a total of six 1:2 scaled composite beam models, and conducts monotonic loading tests to study the failure process, failure mode, ultimate bearing capacity, deformation, and local strain of some typical measuring points of the new composite beam. The steel and concrete composite beam with the molybdenum tailing has the similar mechanical behavior for each ratio of the shear span to the effective depth with that of the steel and concrete composite beam. In addition, they have a little difference in the failure processes for each ratio of the shear span to the effective depth, whereas they show typical diagonal compression failure mode for the ratio of the shear span to the effective depth is equal to 1 and the representative shear-compression failure mode for the ratio of shear span to effective depth is 2, and have no obvious difference in failure mode for each ratio of the shear span to the effective depth. Their shear resistance mechanism is basically the same. Furthermore, based on the validated finite element model, this paper conducted a parameter extension analysis. The finite element results show that: The ultimate load bearing capacity of the steel and concrete composite beam with molybdenum tailing varies significantly with the beam section size (beam section width and beam depth), reinforcement ratio, and the ratio of the shear span to the effective depth; Whereas it has little relation to the steel plate thickness. This provides the necessity and feasibility to use the steel and concrete composite beam with the molybdenum tailing in engineering practice. The proposed equation in this study is based on the previous researches and the simulated and test results. The proposed equation is rigorous and thorough and the predicted results are highly accurate and effective.

Experimental and numerical study on the blast resistance of C-shaped doubled steel concrete slab (C-DSCS) with L-shaped connectors

This study aims to explore the blast resistance of C-shaped doubled steel concrete slabs (C-DSCS) with L-shaped connectors. These slabs utilize the superior compressive strength of concrete and enhance the load-bearing capacity by following a load path similar to that of arch structures. The dynamic behaviors and energy dissipation of the C-DSCS with L-shaped connectors were experimentally and numerically investigated under near-field explosion. Firstly, the pressure–time curve of the explosion was obtained by the pressure sensor in the test. Then, a finite element model (FEM) of the C-DSCS specimen was established through the LBE algorithm, and the accuracy of the finite element model was experimentally validated. Finally, parametric analyses was carried out to investigate the steel plate thickness, explosion distance and spacing of connectors on the dynamic response of the C-DSCS. The results indicated that the C-DSCS specimen had good integrity without failing or severe destruction under the explosion. A small number of oblique cracks appeared in the concrete infill near the free side of L-shaped connectors, which can effectively exert the compressive strength of the concrete. Concrete and bottom steel plate were the main energy-consuming component for C-DSCS and dissipated more than 78% of the explosive energy. In addition, L-shaped connectors also played a certain role in absorbing explosive energy, which can effectively reduce the maximum deflection of the specimens by decreasing the spacing of connectors. This paper provides a basis for theoretical analysis of dynamic response of C-DSCS subjected to close-in explosion, laying a foundation for further design methods.

Axial compressive behavior of corroded double-steel-plate composite shear wall with binding bars

Steel structure is susceptible to corrosion, and corrosion will seriously affect its own load-bearing capacity and service life. In this paper, the axial compressive behavior of double-steel-plate composite shear wall (DSCW) with binding bars under different corrosion degrees is experimentally studied. The typical failure modes include the steel plate local buckling, binding bars fracture, concrete crushing, and steel plate weld tearing. The increase of corrosion rate has unfavorable influence on the axial compressive bearing capacity, initial stiffness, and ductility of DSCW. Finite element (FE) models are established to further investigate the axial compressive behavior of DSCW. It is concluded that the concrete and steel plate strength grade, the concrete section area, the steel plate thickness, and the binding bars diameter and spacing significantly affect the axial compressive bearing capacity of DSCW. A formula calculating the axial compressive bearing capacity of corroded DSCW with binding bars is proposed. The formula agrees well with the test results and can provide a reference for the engineering application.

Numerical investigation on seismic performance of reinforced rib-double steel plate concrete combination shear wall

Double steel plate concrete composite shear wall (SCSW) has been widely utilized in nuclear power plants and high-rise structures, and its shear connectors have a substantial impact on the seismic performance of SCSW. Therefore, in this study, the mechanical properties of SCSW with angle stiffening ribs as shear connections were parametrically examined for the reactor containment structure of nuclear power plants. The axial compression ratio of the SCSW, the spacing of the angle stiffening rib arrangement and the thickness of the angle stiffening rib steel plate were selected as the study parameters. Four finite element models were constructed by using the finite element program named ABAQUS to verify the experimental results of our team, and 13 finite element models were established to investigate the selected three parameters. Thus, the shear capacity, deformation capacity, ductility and energy dissipation capacity of SCSW were determined. The research results show that: compared with studs, using stiffened ribs as shear connectors can significantly enhance the mechanical properties of SCSW; When the axial compression ratio is 0.3–0.4, the seismic performance of SCSW can be maximized; with the lowering of stiffener gap, the shear bearing capacity is greatly enhanced, and when the gap is lowered to a specific distance, the shear bearing capacity has no major affect; in addition, increasing the thickness of stiffeners can significantly increase the shear capacity, ductility and energy dissipation capacity of SCSW. With the rise in the thickness of angle stiffening ribs, the improvement rate of each mechanical property index slows down. Finally, the shear bearing capacity calculation formula of SCSW with angle stiffening ribs as shear connectors is derived. The average error between the theoretical calculation formula and the finite element calculation results is 8% demonstrating that the theoretical formula is reliable. This study can provide reference for the design of SCSW.

Confinement mechanism of rectangular CFST components using double horizontally-corrugated steel plates

This paper presents experimental and analytical investigations on the confinement mechanism of a novel rectangular concrete-filled steel tube (CFST) component for use in composite shear walls. The CFST component consists of a steel tube made by welding double horizontally corrugated steel plates and double flat steel plates, and infilled with concrete. Tests of eight components and finite element analysis of twenty-three components under uniform compression were conducted to explore confinement mechanism of the novel tube to core concrete. The impacts of several factors such as steel plate thickness, nominal sectional aspect ratios, slenderness ratios, and the strength of the steel and concrete on the confinement mechanism were analyzed. The non-uniform confinement mechanism of horizontally corrugated steel plates was investigated based on their vertical and horizontal strain responses at the wave crests, middles, and troughs. The test results and numerical simulations demonstrate that the proposed CFST components exhibited desirable axial compressive behavior with ductile failure modes. The tested specimens with nominal sectional aspect ratios ranging from 1.2 to 2.39 had strength indexes greater than 1.17. Even with a width-thickness ratio of 325.33, the horizontally corrugated steel plates effectively confined the core concrete. Furthermore, this research proposed a design strength model that considered the confinement effects of corrugated plates. The model accurately predicted the experimental and numerical results.

Experimental investigations of residual stresses in thick high‐strength steel plates

AbstractResidual stresses strongly influence the load‐bearing capacity of steel members under compressive axial loads. Current developments in steel and steel‐concrete composite structures imply the use of high‐strength steel grades up to 960 MPa. For such steel plates, only limited results of residual stress investigations are known so far. The authors have applied two established measuring methodologies like the sectioning method and X‐ray diffraction to determine the residual stress state of 40 mm thick steel plates and different widths. The results show that the distribution and amount of longitudinal residual stresses are mainly determined by the oxyfuel‐cutting procedure used to manufacture the specimens. The distribution over the thickness could be determined by X‐ray diffraction. Compared to the results of examinations on lower‐grade steel plates an assumed correlation of residual stresses and steel grades could not be observed. Consequently, residual stresses have a reduced influence on the load‐bearing capacities of structures prone to buckling as the ratio of yield strength to residual stress states declines significantly.

Influence of heat input on the mechanical characteristics, corrosion and microstructure of ASTM A36 steel welded by GTAW technique

The Gas Tungsten Arc Welding process weld for the 4 mm thickness of the ASTM A36 steel plate with varied heat input parameters of 0.608 kJ/mm, 0.900 kJ/mm and 1.466 kJ/mm, respectively. The effect of different heat inputs on microstructure, corrosion, and mechanical characteristics of developed weld joints are examined by three zones: heat-affected zone, welded zone, and base metal zone. The optical microscopic results of weld joints illustrate that fine grain structure leads to enhance welding strength. It is revealed that the increased heat input parameter on the weld joint shows a decreased tensile strength and hardness of the weld joint. The corrosion resistance of the weld joint is evaluated by Potentio-dynamic polarization. It facilitates that the corrosion rate of the weld joint is decreased with increasing heat input, which results indicate the best and worst corrosion micrograph of the polygonal ferrite and ferrite plus polygonal ferrite. However, the weld joint prepared with 0.900 kJ/mm heat input found maximum corrosion resistance.

Prediction of roll wear and thermal expansion based on informer network in hot rolling process and application in the control of crown and thickness

The inaccuracy of roll thermal expansion and roll wear settings affects strip steel plate shape and thickness in hot-rolling process. Roll wear and thermal expansion are nonlinear time series that cannot be neglected in the roll engineering. In order to make up for the shortcomings of the existing models, a novel prediction model of roll thermal expansion and roll wear based on Informer is developed. Firstly, multiple experiments are conducted to determine hyperparameter such as training epoch, dropout, batch size and learning rate. Then, the predicted results of finishing mill group (F1–F7 stand) are compared with the long-short-term memory (LSTM) model, the artificial neural network (ANN) model and the recurrent neural network (RNN) model. The results show that the model based on Informer network has highly accurate in predicting roll thermal expansion and roll wear. Finally, the application results show that the hit rate is 98.412 % within the tolerance range ± 4 μm and the hit rate within the ±40 μm thickness tolerance deviation range reach 98.94 % which proves that the roll wear and thermal expansion model based on Informer has outstanding advantages in the hot rolling shape control system.

Dissimilar autogenous TIG joint of Alloy 617 and AISI 304H steel for AUSC application

To reduce costs and improve high-temperature performance in Advanced Ultra Super Critical (AUSC) boilers, it is necessary to weld austenitic steel to Inconel alloy. In this study, the autogenous tungsten inert gas (TIG) welding process was used to join Alloy 617 and an austenitic AISI 304H steel plate of thickness 5 mm. Microstructural analysis showed that the microstructure formation was uneven along the weldments, with columnar and cellular dendrites near the interface while the central area of the weld exhibited a combination of columnar, cellular, and equiaxed dendrites. The use of energy dispersive spectroscopy and electron probe micro-analysis unveiled the presence of an unmixed layer at the interface between the weld and AISI 304H steel. Furthermore, a notable variation in the concentration of alloying elements such as Fe, Cr, Ni, Co, and Mo was observed. Within the weld metal, inter-dendritic areas showed the presence of precipitates rich in Cr, Ti, and Mo. Meanwhile, the heat-affected zone (HAZ) of Alloy 617 exhibited the presence of phases like Cr and Mo-rich M23C6 as well as Mo-rich M6C. Hardness tests showed non-uniform hardness along the weldments, with a hardness of 199 ± 6 HV in the weld metal and 225 ± 4 HV in Alloy 617 HAZ, and 207 ± 7 HV in AISI 304H HAZ. The Mo and Cr segregation in the inter-dendritic spaces led to a decline in the tensile properties of the welded parts and resulted in failure from the region of the weld metal.

The seismic behaviors of steel-concrete-steel composite walls with dumbbell-shaped connectors

In this study, quasi-static tests were conducted on six steel-concrete-steel composite wall (SCSCW) specimens with novel dumbbell-shaped connectors (DSCs) to investigate their seismic performance. The research parameters included the connector arrangement scheme and the axial load. The failure mode, load-displacement curve, and strain data were analyzed in detail. All the specimens exhibited flexural failure, and the experimental phenomena included the local buckling of external steel plates and compressive failure of internal concrete. The local buckling located between the foundation and first row of connectors, had a limited effect on the bearing capacity of the specimens. The connectors effectively controlled the buckling range of the external steel plates. With increasing axial load, the deformation capacity of the specimens decreased significantly. Under the same displacement, the greater the axial load, the greater the secant stiffness, and the higher the accumulated energy dissipation value. When the load reached its peak value, the yield range of the bottom front steel plates of specimen with large axial load was less than that of the specimen with small axial load. The theoretical formula accurately calculated the flexural bearing capacity of SCSCWs, and the maximum error and the average ratio which was defined as experimental value to calculated value were 9% and 1.02, respectively. The horizontal load-displacement relationship of the specimens was calculated using the OpenSees software, and the maximum error of the bearing capacity was 4%. The parametric analysis showed that increasing the steel plate thickness can effectively improve the bearing capacity of SCSCWs.

Early Shrinkage Modeling of Complex Internally Confined Concrete Based on Capillary Tension Theory

This paper evaluates the shrinkage performance of concrete under complex internal constraint environments comprising steel plates, studs, and reinforcement to investigate their respective influence laws on the shrinkage performance of concrete. An early shrinkage model of concrete under complex internal constraints was established based on the theory of capillary tension, and the effects of steel plate, nails, and steel reinforcement on the shrinkage performance of concrete were theoretically analyzed. Six sets of concrete-constrained shrinkage tests and pore structure tests were then performed under different internal constraint conditions with the steel plate thickness, reinforcement diameter, and stud-related parameters (stud diameter, height, and spacing) as research variables. The test results demonstrate that the pore structure of concrete increases with the increase in the constraint coefficient, and that the increase in the pore structure will cause a decrease in the capillary pore stress, which is the driving force of concrete shrinkage. Its decrease will inevitably lead to a decrease in concrete shrinkage. By comparing the calculated values of the shrinkage model with the measured values, it is found that the average value of the prediction error is less than 15%, which reveals that the predicted values of shrinkage are in good agreement with the measured values and proves that the model can effectively predict the shrinkage of concrete that is restrained by steel plates, pins, and reinforcing bars.

Experimental investigation of the flux-assisted TIG weldment of super duplex stainless steel

The focus of the current article is on the microstructure and behavior of the autogenous joints produced by ATIG welding on 6 mm thick super duplex stainless steel plates. The blending of two mostly used metallic oxides TiO2 and SiO2 is used as flux materials in the varied ratio to carry out ATIG welding. The essential processing requirements like welding current maintained at 160A and argon gas flow velocity maintained at 16 L/minute are used for the weld joint experiment. The complete study of weld morphology, various zone of weld region, weld interface microstructure, and mechanical and corrosive characteristics are all studied in this investigation. In comparison to other varied ratios of bicomponent flux-assisted welded joints, the bicomponent flux compromised of 50% of TiO2 and 50% of SiO2 assisted weldment showed excellent tensile strength, impact strength, and corrosion resistance.

Experimental Research on the Impact Resistance of Partially Precast Concrete Beams Strengthened with Bonded Steel Plates

A structure may be exposed to a range of unexpected loads throughout its full life cycle. Partially precast concrete (PC) beams refer to the process of manufacturing concrete beams in which one part of the component is pre−fabricated in a factory and the other part is completed at the construction site. Through the test, it is possible to better ensure the safety and dependability of the PC composite beams under impact load by examining the reinforcement effect, structural toughness, and damage mode of PC composite beams with bonded steel. Additionally, a scientific basis and practical guidance are provided for the actual project. Their impact resistance can significantly affect the overall safety of a structure when subjected to an impact load. Three of the four PC beams used in this investigation were strengthened with steel plates. Residual flexural bearing capacity tests and drop weight impact tests were then conducted. The impacts of steel plate thickness and U−shaped steel plate hoops on the failure mechanism and dynamic response of the component were investigated. The dynamic responses obtained from the experiments included the displacement–time history curve, impact force, and support reaction force. In order to explore the failure mechanism of the partially precast beam during the impact process, a staged analysis was conducted based on the failure mode and dynamic response characteristic values of each curve. Residual flexural bearing capacity tests were used to examine the residual flexural bearing capacity of PC beams strengthened with bonded steel plates. The results of the research reveal that the failure mechanisms of each test beam are bending–shear failures. With the increase in bonded steel thickness, the peak mid−span displacement reduced by 6.55%, the residual mid−span displacement decreased by 29.53%, and the residual flexural bearing capacity improved by 25.02%. With the adoption of U−shaped steel plate hoops, the residual flexural bearing capacity significantly increased while the peak mid−span and residual mid−span displacements both decreased.

Influence of TiN Inclusions and Segregation Bands on the Mechanical Properties and Delayed Crack in Thick NM550 Wear-Resistant Steel.

The formation mechanism of the delayed crack after flame cutting and mechanical properties in thick NM550 wear-resistant steel are studied by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and an electron backscattered diffractometer. The delayed crack is formed at the segregation zone (SZ) located in the center of the 65 mm thick steel plate. The strength of the non-segregation zone (NSZ) with a martensite microstructure is slightly higher than that of SZ with a mixture microstructure of martensite plus bainite, and the plasticity of NSZ is significantly better than that of SZ. There exists a more severe segregation in the SZ, and only a slight segregation in the NSZ. The average grain sizes of the segregation bands in the NSZ and SZ are 15.72 µm and 6.76 µm, respectively. The number density of TiN larger than 5 µm in the NSZ and SZ is 0.031 and 1.156 number/mm2, respectively. Therefore, a high hardness segregation band with fine grains and a high dislocation density, along with the large number of coarse TiN inclusions within it, results in delayed cracking. For TiN inclusions close to the crack, microvoids or microcracks around the TiN are formed, and the delayed crack will propagate along the edge of the TiN or through the TiN inclusions.

Study on plug-pin energy-dissipating joint with integrated mild steel dampers

Plug-pin joints are designed for easy assembly and fast construction. Full-scale experiments were carried out on three exterior beams-to-column joints subjected to reversal cyclic loading. It has been proved from experimental results that the proposed connection not only guarantees structural integrity but also moves the plastic hinge away from the column edge. Based on the experimental results, a novel plug-pin connection with integrated mild steel dampers is proposed. The energy dissipation joint fully adopts a dry connection method, and the joint's ductility is significantly improved by the integrated energy-dissipating steel plates. Finite element models are established to study the effects of different diameters of steel bars and thicknesses of energy-dissipating steel plates on structural response and mechanical properties under low cyclic reciprocating loads. Parameter studies were carried out, and the obtained results indicate that the proposed joints can bear a greater displacement load than that of cast-in-place joints and achieve greater energy dissipation. The maximum bearing capacity of the joint can be improved by increasing the thickness of the energy-dissipating steel plates, but the bearing capacity decline period of the joint will appear in advance under the same order of loading. If designed properly, structures installed with the plug-pin joint will be expected to adjust the order of plastic hinge development, thus achieving better seismic performance.