Frame Columns Research Articles

Effect of Global Geometric Imperfections on the Cyclic Response of Moment Resisting Frame Columns

Effect of Global Geometric Imperfections on the Cyclic Response of Moment Resisting Frame Columns

Analysis on the Seismic Behavior of RC Frame with Different Special-shaped Columns at the Bottom

In order to study the seismic behavior of the bottom large-bay frame with different special-shaped columns, the numerical models of the special-shaped columns frame with ordinary, dark and square columns at the bottom are established using the finite element analysis in ANSYS. The three type special-shaped Frame are performed with nonlinear time-history dynamic method under earthquakes. The dynamic characteristics and seismic response of the three type RC Frame are conducted. The weak parts and the development of the plastic hinges on the end of beams and columns are discussed. The results show that the special-shaped frame with bottom square columns can overcome the weak phenomenon at the bottom, and provide outstanding seismic performance compare with the other two frames.The seismic behavior of the special-shaped columns frame with dark columns is better than the normal special-shaped columns, however it can not effectively overcome the weak parts of the bottom floor. The results can provide a theoretical basis for the engineering application of the frame with special-shaped columns.

Experimental and Numerical Investigations of RC Frame Stability Failure under a Corner Column Removal Scenario

In recent decades, interest in the resistance of buildings and structures to progressive collapse has been increasingly sparked in research communities. Although several experimental, numerical, and analytical research projects on the robustness of building frames under a column removal scenario have been implemented, some aspects of this problem remain understudied. These aspects encompass failure mechanisms of reinforced concrete frames with slender columns, as well as criteria used to evaluate such failures. This paper focuses on experimental and numerical investigations of the structural behavior and failure of a scale reinforced concrete frame with slender columns under a sudden corner column removal scenario. In addition, we analyze the stability failure mechanism of a reinforced concrete frame with slender columns and the tangent stiffness criterion, which allow for evaluation of the ultimate state of a structure subjected to an accidental impact. A scale physical model of a reinforced concrete frame of a multistory building was designed and tested using the theory of functional similarity. For numerical study purposes, a finite element model was made that exactly the same as the test frame. We validated the findings by comparing simulation results and experimental data. The studies on the behavior of a reinforced concrete frame subjected to quasistatic loading with unequal concentrated loads identified the load transfer between columns through beams. Although these effects were minor in the frame under consideration, they can become more significant in cases of long-term loading. Numerical simulation and physical modeling of an accidental impact allowed for identification of the mechanism of load capacity exhaustion triggered by stability failure. Such failure was fragile. The moment of stability failure of the column of the experimental frame corresponded to the extremum on the force–displacement curve, indicating that zero tangent stiffness was reached. Hence, a criterion of tangent stiffness can be proposed for evaluation of the ultimate state of a structure subjected to an accidental impact.

Mechanical performance and design method of two-side-connected SPSW reinforced on free edges

In this study, a two-side-connected steel plate shear wall (SPSW) reinforced by cold-formed steel (CFS) strips on free edges is proposed. This structure has several advantages, including the ability to avoid additional bending moments on the frame column, convenient layout, and lightweight structure with good assembly effects. To understand the mechanical performance of the novel structure, horizontal reciprocating tests were conducted on two specimens; one was a two-side-connected SPSW reinforced on free edges without a frame and the other with a concrete-filled steel tube frame. The results showed that the two-side-connected SPSW reinforced on free edges still possessed good bearing and energy dissipation capacities. Finite element (FE) models were established, and the numerical analysis results were compared with the test results. Based on the verified FE model, a parametric analysis was performed, leading to the derivation of formulas for calculating the minimum stiffness ratio and buckling bearing capacity. Additionally, formulas for the yield bearing capacity and ultimate bearing capacity were derived based on the calculation formula for the buckling bearing capacity. To improve the design efficiency, a simplified truss model (STM) was proposed. The stress–strain relationship of the equivalent truss was established based on the aforementioned bearing capacity calculation formulas. The STM calculation results were compared with the test results, indicating a high level of accuracy and significantly improved calculation efficiency.

Research on the Application of Reinforced Concrete Building Structure Reinforcement Technology in Engineering

Old buildings because of long service life or natural damage, easy to appear durability, bearing capacity, stability decline, in order to ensure the safe use of building structure must take reinforcement measures. Increasing section method, carbon fiber cloth outsourcing, pasting steel plate method, planting reinforcement method and so on are commonly used reinforced concrete building structure reinforcement technology, but each technology is not the same application conditions and application effect. In this paper, the reinforcement and renovation project of a frame structure industrial plant in Tonglu, Zhejiang Province is taken as an example. Firstly, the basic ideas of reinforcement design and the basis of selection of reinforcement and renovation technology are outlined. Then, the application points of different reinforcement and renovation technologies are emphatically analyzed from four parts: basement frame column, first floor frame column, frame beam and sandwich structure. It provides some reference for the reinforcement and renovation of modern steel concrete building structure.

Embodied Carbon Minimization for Single-Story Steel Gable Frames

As the construction industry, especially steel construction, contributes to a large portion of global greenhouse gas emissions, sustainable structural design has become a necessity to achieve the world vision of reaching net zero emissions by 2050. As steel portal frames are the most used structural system for single-story buildings, the main objective of this study is to determine the optimal steel portal frame configuration using prismatic and/or non-prismatic members to achieve the least embodied carbon. Five different portal frame configurations are considered under the effect of five distinct loading conditions. The results led to developing design charts consisting of contour plots showing the embodied carbon per unit of volume enclosed by the steel frame for different frame configurations, loading conditions, span lengths, and column heights. In addition, by increasing the number of member divisions, design variables, and non-prismatic segments, the average embodied carbon of the steel portal frames can be significantly reduced by about 14.34% up to 26.47% relative to the configuration with only prismatic members.

Seismic stability of steel wide-flange columns in ductile moment-resisting frames: out-of-plane response and design recommendations

Seismic stability of steel wide-flange columns in ductile moment-resisting frames: out-of-plane response and design recommendations

Mechanical properties and automatic design method for rural residences with hinged frames and cold-formed thin-walled stiffened walls

At present, the overall construction quality of rural residences is still relatively poor, and the seismic performance of their structural systems is insufficient. In this study, quasi-static tests were carried out on three cold-formed thin-walled stiffened steel plate wall (CFSW) specimens infilled in a single-span two-story 1/2 scale hinged special-shaped column frame. The seismic performance of each specimen was evaluated by comparing the bearing capacity, ductility, stiffness degradation, energy dissipation capacity, and strain. The results show that the filling of concrete and gypsum in the column helps improve the bearing capacity of the structure but has no notable effect on the stiffness. The brittle failure phenomenon in the filled concrete specimens is obvious, and those specimens either without filler or whose columns are filled with gypsum show better ductility and energy dissipation capacities. A finite element (FE) model was established and validated, and the influence of parameters such as the connection method between the wall and frame, the shear-span ratio of the wall, the thickness of the stiffened wall, and the number of hat-section cold-formed steel (HCFS) stiffeners upon the structural system was analyzed. In combination with the test and the FE analysis results, the calculation method for horizontal bearing capacity of CFSW restrained by HCFS stiffeners and engineering design suggestions were put forward. In addition, an automatic program for the forward generation of the CFSW was designed, and the application of the system in practical engineering was verified using Midas software.

Numerical analysis of traditional Chinese timber structure: Simplified finite element model and composite elements of joints

Mortise-tenon (M-T) joint, column foot joint, and Dou-Gong joint play a key role in the seismic behavior and energy dissipation of traditional timber structures. To simplify the modeling process and predict accurately the hysteretic behaviors of traditional timber joints as well as the global seismic responses of traditional timber structures, three types of composite elements, which were composed of varying non-linear one-dimensional spring elements available in the ANSYS finite element (FE) software, were proposed to characterize the hysteretic performance of the M-T joint, the column foot joint, and the Dou-Gong joint, respectively. The beam element was used for simulating the timber components with large size and not easily damaged. The parameters of the composite elements were identified from the simplified hysteretic model or test hysteretic curve of each type of joint. The simplified FE models of the M-T joint, M-T jointed timber frame, column foot joint, and Dou-Gong joint were developed, and verified using the cyclic loading tests of joints, respectively. Based on the validated composite elements and simplified FE models of varying joints, the three-dimensional simplified bar system FE model of a 1/3.52-scaled palace-style ancient timber structures was established using the ANSYS, and also validated using the shaking table tests, in terms of its dynamic characteristics and responses. Good agreements between the model predictions and test results were observed. Additionally, parametric analyses were performed, while revealing and quantifying the effects of performance degradation for the M-T joint, column foot joint, and Dou-Gong joint on the dynamic responses to the structure. It is found that the damage to the Dou-Gong joint had little effect on the maximum story drift of column frame layer, however, the damage to the M-T joint and column foot joint would significantly increase the maximum story drift of column frame layer. When the damage degree of the M-T joint, Dou-Gong joint, and column foot joint in the structure was up to 60%, the maximum story drift ratios of column frame layer were close to 1/48, 1/50, and 1/39, respectively, the maximum story drift ratios of Dou-Gong layer were approximately 1/164, 1/98, and 1/125, respectively.

Experimental Investigation and Numerical Simulation of Corrugated Steel Plate Shear Wall Considering the Gravity Load

The corrugated steel plate shear wall (CSPSW) has high strength, ductility, and energy dissipation capacity and can be used as the lateral force-resisting system of multi-story and high-rise buildings. The vertical load transmitted by the upper floor and frame columns may inevitably act on the corrugated steel plate shear wall. However, the influence of the gravity load on the performance of the corrugated steel shear wall is not considered in most studies. To investigate the behavior of corrugated steel plate shear walls considering the actual gravity load, four scaled SPSWs under lateral and vertical loading were tested. The specimens’ failure mode, envelope curves, and hysteretic curves were analyzed. A numerical simulation model was established based on the validation of the experimental test on the SPSWs. The results showed that the hysteresis curves of the test were consistent with those of the simulation results. Finally, parametric analysis was conducted on the SPSWs with different types of infill plates, height-to-thickness ratio, and gravity loads.

Strength Calculation of the Coupling of the Floor Slab and the Monolithic Reinforced Concrete Frame Column by the Finite Element Method

This study aims at developing the concept of fragmentation of the frame to assess the load-bearing capacity of the floors. As a rule, a frame-rod design scheme is used under the finite elementmodeling of high-rise buildings made of monolithic reinforced concrete. Numerical experiments using volume-rod and volume-plate models of a repeating structural fragment were performed on a test example of a six-span three-storey monolithic reinforced concrete frame. Practical recommendations have been developed for the refined strength calcula-tion of the floors of monolithic reinforced concrete frames of multistorey buildings. Materials and Methods. Computational experiments were performed using the ANSYS Mechanical software package, in which the finite element method was implemented in the form of a displacement method. A plate-rod ensemble of finite elements was used to simulate the stress-strain state of a monolithic reinforced concrete frame. The refined calculation of the coupling zone of the floor slab and column under static loading was performed using solid, beam, truss and plate elements. Results. An engineering technique has been developed for numerical analysis of the stress-strain state of the coupling of the floor and the column of the reinforced concrete monolithic frame under static loading. The most accurate result was provided by a finite element model constructed using beam finite elements as reinforcing rods. Discussion and Conclusions. The developed technique of numerical modeling of the coupling of the floor and the column made it possible to estimate the real strength margin of this node, taking into account the real geometry of reinforcing grids, as well as to clarify the bearing capacity of a monolithic reinforced concrete frame under various loading scenarios.

Influence of the Vertical Component of Yangbi Ground Motion on the Dynamic Response of RC Frame and Brick-Concrete Structure

An earthquake of magnitude 6.4 occurred in Yangbi County, Yunnan Province on 21 May 2021, with a focal depth of 8 km, and strong ground motion with vertical components was monitored by Yangbi station (53YBX). A total of 14,122 houses were damaged in Yangbi in the earthquake, and 232 of them collapsed. Vertical components of ground motions have been gained more attention for its effect on structure’s seismic response in epicenter or near-fault regions at present. Taking the three earthquake ground motions of Yangbi, Chi-Chi, and Loma Prieta as inputs, and modeling based on Perform-3D, this research carried out the seismic dynamic time history analysis of an RC (reinforced concrete) frame structure and a brick-concrete structure under both horizontal and vertical working conditions. The results showed that vertical components of the three ground motions had no evident impact on the top horizontal displacement and acceleration of the two types of structures. Among the three ground motions, the vertical component of Yangbi ground motion has largely influenced the top vertical displacement, acceleration, and axial force of the frame column bottom (or masonry wall bottom). The vertical component had different amplification effects on the axial pressure and the bending moment of a single column at the bottom of the RC frame structure, thus causing resonance amplification effect of the brick-concrete structure floors and amplifying the vertical acceleration of the top floor. In addition, it considerably increase the maximum axial tensile strain of masonry walls and the possibility of faster tensile failure of the brick-concrete structure. Influence of vertical ground motion on the bearing capacity of RC frame structure’s columns and the brick-concrete structure’s masonry walls should not be ignored. The results of the research may provide a reference for the earthquake-resistant design of building structures, especially the earthquake-resistant design considering the vertical seismic effect.

High-precision deformation analysis of yingxian wooden pagoda based on UAV image and terrestrial LiDAR point cloud

The monitoring of wooden pagodas is a very important task in the restoration of wooden pagodas. Traditionally, this labor has always been carried out by surveying personnel, who manually check all parts of the pagoda, which not only consumes huge manpower, but also suffers from low efficiency and measurement errors. This article evaluates the feasibility of combining portable 3D light detection and ranging (LiDAR) scanning and unmanned aerial vehicle (UAV) photogrammetry to perform these inspection tasks easily and accurately. The wooden pagoda's exterior picture and inside point cloud are acquired using a UAV and a LiDAR scanner, respectively. We propose a feature−based global alignment method to register the site point cloud. The error equation of the column of observed values is utilized as the beginning value of the feature constraint for global leveling. The beam method leveling model solves the spatial transformation parameters and the unknown point leveling values. Then, the Structure from Motion (SfM) algorithm of computer vision is used to realize the fusion of the dense point cloud of the exterior of the wooden pagoda generated from multiple non−measured images by global optimization and the LiDAR point cloud of the interior of the wooden pagoda to obtain the complete point cloud of the wooden pagoda, which makes the deformation monitoring of the pagoda more detailed and comprehensive. After experimental verification, the overall registration accuracy of the Yingxian wooden pagoda reaches 0.006 m. Compared with the scanning point cloud data in 2018, the model is more accurate and complete. By analyzing and comparing the data of the second floor of the wooden pagoda, we knew that the inclination of a second bright layer and a second dark layer is still developing steadily. Overall, the western outer trough inclines thoughtfully, and the column frame slopes from southwest to northeast. Some internal columns showed a negative offset in 2020, and the deformation analysis of a single column was realized by comparing it with the standard column model. The main contribution of this method lies in the effective integration of UAV images and point cloud data to provide accurate data sources for good modeling. This research will provide theoretical and methodological support for the digital protection of architectural heritage and GIS data modeling. The analysis results can provide a scientific basis for the restoration scheme design.

Exposure of the load capacity of the RC structural system under corrosion damage to columns

A number of accidents, such as the partial collapse of a residential building in Surfside on June 24, 2021, or the collapse of the roof structure of Basmanny Market in Moscow on February 23, 2006, show that aggressive medium impacts on reinforced concrete structures lead over time to a decrease in their strength resistance resource under accidental impacts. At the same time, the investigations in this field mainly deal with structural members under bending, while eccentrically compressed and corroded reinforced concrete members have been considered either in particular aspects or the obtained solutions are rather complicated for their practical application. In this regard, the purpose of the article was to assess the influence of the corroded depth on the load capacity of eccentrically compressed reinforced concrete columns of structural frames, as well as to predict the time of exhaustion of their load capacity under constant serviceable loads. The paper adopted the phenomenological model of V.M. Bondarenko to take into account long-term corrosion processes. It had been established that an increase in the corroded depth leads to a decrease in the load capacity of eccentrically compressed reinforced concrete members due to a decrease in the effective cross-sectional depth and effective slenderness ratio. The relative depth of the destroyed concrete varies depending on the current stress-strain state of the structural member. The time to reach the critical corroded depth depends significantly on the parameters of aggressive medium and the stress-strain state of the structural member and may differ by several times when implementing avalanche or descending damage kinetics.

Experimental and numerical investigations into seismic behavior of corroded steel frame beams and columns in offshore atmospheric environment

With the strong promoting of “national carbon peak and carbon neutrality” strategy and the continuous deepening of “performance-based seismic design” concept, the seismic performance evaluation field of Chinese steel structures has developed rapidly. Nevertheless, previous studies are generally aimed at new building structures, ignoring the seismic performance degradation characteristics caused by the durability loss of existing structures under environmental erosion. Thus, in this paper, accelerated offshore atmospheric corrosion and quasi-static cyclic loading tests were carried out on five steel frame beams and four steel frame columns. The effects of corrosion level on the failure mechanism, hysteretic behavior, skeleton curve, bearing capacity, ductility, stiffness degradation and energy dissipation of steel frame members were revealed and analyzed in detail. The test results indicate that with an increase in corrosion level, the appearance of plate local buckling, steel cracking and final failure shows a forward tendency, and all seismic performance indexes significantly decrease. Moreover, the deterioration models of the maximum load, ultimate displacement and cumulative energy dissipation with weight loss rate for corroded steel frame beams and columns were proposed. In addition, a finite element analysis method for corroded steel frame members was established and validated, which considered the corrosion damage and introduced a nonlinear mixed hardening constitutive model and a stress triaxiality dependent ductile damage criterion. On this basis, the parametric analysis was further presented to systematically study the influence of corrosion level, plate width - thickness ratio and its assembly factors, and stress conditions on the mechanical performance of H-shaped steel members, then obtaining the regular expressions of bending capacity and plastic rotation capacity.

Shear capacity prediction of buckling-restrained SPSWs with beam-connected only using response surface method

The cold-formed steel (CFS) buckling-restrained steel plate shear walls (BRSPSW) with beam-connected only have the characteristics of avoiding additional force on the frame column, flexible arrangement and excellent seismic performance, and can also facilitate the realization of the building function of heat preservation and sound insulation. This study aims to investigate the cyclic shear behaviour of CFS BRSPSW with beam-connected only experimentally and numerically. Firstly, two 1:3 scale specimens were designed and tested. The experimental results showed that the CFS BRSPSW with beam-connected only is a good lateral force resistant structural system. Moreover, the yield shear capacity of the specimen was increased by 10.4% after the hat-shaped CFS stiffeners were arranged. Afterwards, a finite element (FE) model was performed and validated against experimental results in terms of failure modes and hysteresis curves. Based on the validated FE model, two specimens were supplementary analysed to obtain a relatively efficient spacing of CFS stiffeners. To effectively improve the accuracy and efficiency in the early design stage, the response surface method (RSM) was introduced to predict the shear capacity of CFS BRSPSWs with beam-connected only in this study. The results show that the RSM prediction model can accurately predict the shear capacity of CFS BRSPSWs with beam-connected only, and can also effectively improve the accuracy and efficiency in the early design stage - the mean value of the FE calculation results to the response surface prediction results is 1.00, and the coefficient of variation (COV) is 0.0003.

Cyclic response of precast concrete columns connected with cast-in-place UHPC in plastic hinge region

Ultra high performance concrete (UHPC) is a promising material for lap splice connection of steel bars in reinforced concrete (RC) precast structures given its high compressive strength, its high toughness, and its high bond strength with steel bars. This paper focuses on the cyclic response of bottom frame columns connected by UHPC in the plastic hinge region. The effect of lap length of longitudinal bars in UHPC (6d, 8d and 12d, d = diameter of longitudinal bar), axial load ratio and stirrup ratio of the UHPC connection region on the global response of the columns were presented and analyzed, and a cast-in-site RC column was prepared for comparison. The behavior of the UHPC connected columns was flexural dominated, but columns with 6d and 8d lap length failed due to the gradual bonding degradation between UHPC and longitudinal bars, and the column with 12d lap length failed due to UHPC crushing. It was demonstrated that a 8d lap length could achieve equivalent lateral bearing capacity and ductility to the control RC column, but the lap length should be greater than 8d when applying UHPC connection technology in seismic regions to ensure the energy dissipation. Column with lower axial load ratio (0.17) exhibited lower ductility because shear sliding occurred between the interface of UHPC and footing at the post-peak stage. The UHPC connected specimens exhibited higher resilience and better damage resistance in earthquake because the ratios of the residual displacements to the corresponding peak displacements were between 17 and 39%. Besides, a flexural capacity model for the columns was developed and the results predicted by the model agreed well with the experimental results.

Pseudo-dynamic experimental study on seismically isolated prefabricated RC structure with roller-bearing subjected to mainshock-aftershock sequences

For the series seismic isolated structure with isolation bearings at the top of the frame columns on a certain floor, the differences in mechanical properties between it and its corresponding aseismic structure are mainly caused by the isolated system consisting of the isolation bearing and column beneath it. Herein, taking the prefabricated isolated system as the research object, a novel roller-bearing (RB) with a displacement-restricted device and a different type of column-to-column connection joint (CCCJ) are presented, the two are both applied to form seismically isolated prefabricated reinforced concrete (RC) structure using roller-bearing (SIPRCS-RB). The seismic performance of the prefabricated isolated system under mainshock-aftershock sequences (MS-AS) is evaluated using a pseudo-dynamic experiment. The strain, overall bearing capacity, and cumulative hysteretic dissipated energy (CHDE) of the concrete at the connection joint in the prefabricated column have not changed significantly, compared with corresponding parts in the cast-in-situ column, while the strain of the rebars has decreased considerably, indicating that the proposed CCCJ is reliable and has excellent seismic performance. Contrasting the responses of the prefabricated column and the RB under a single mainshock with that under the MS-AS, when the aftershock strikes, the CHDE of both components will increase markedly due to the previous damage induced by the mainshock, but the increase in deformation is relatively minor; the larger the peak ground acceleration (PGA) of the mainshock is, the greater the increase in CHDE of the components under aftershocks. Therefore, for the SIPRCS-RB, the effect of the MS-AS on seismic performance should be considered.

Introducing a new seismic resisting system with dual linked column frame and rocking motion

This paper proposes a novel Dual-Linked Column Frame (DLCF) system with the rocking motion of moment frame column bases. The novel Dual-Linked Column Frame with Rocking motion (DLCFR) increases the seismic capacity of the moment frame and the linked beam as a structural fuse to dissipate energy. Rocking column bases can dissipate energy through fuses that can be repaired easily by being bolted to the column. A dual-linked column pattern in the frame center increases the seismic performance of the linked column frame (LCF) system. The effect of rocking motion on the seismic performance of LCF and DLCF systems has been evaluated by analyzing 13 models with different rocking motion placements and comparing these models with the fixed base condition. The seismic performance of the models has been compared and one model with the desirable seismic performance has been proposed. Incremental Dynamic Analysis (IDA) has been performed to examine the behavior of the 3, 6, and 9-story proposed models using OpenSees. The results showed that rocking motion reduces the failure of the moment frame in the DLCF system. The absorption of the base shear in the Moment Frame (MF) and the Linked Column (LC) in the DLCFR model is 1 and 99% of the total base shear, respectively. The probability of failure in the proposed models of 3, 6, and 9-story are 20%, 15%, and 10% less than the model with a fixed base, respectively. The new seismic system proposed has been able to significantly reduce the probability of failure, floor acceleration, and base shear.

Seismic performance of thin-walled steel and concrete composite column-corrugated steel shear wall structure

This paper presents a new structure called cold-formed thin-walled channel steel and concrete composite column-corrugated steel shear wall (referred to as CSC-CSW), which can significantly improve the lateral resistance of SPSW. Three groups of full-length walls were tested under low-cycle reciprocating loading in order to investigate the effects of axial compression ratio and aspect ratio of steel plates. The experiment discovered that the failure of specimens was mainly caused by the tear of corrugated steel plate and the bearing failure of bolt hole. The results show that with the increase of the axial compression ratio, the average peak bearing capacity, ductility and ultimate displacement are decreased. With the decrease of the aspect ratio of the steel plate, the shear capacity and initial stiffness of the specimen are decreased, but the ductility and energy dissipation capacity are improved. On the basis of the test, 19 refined FEA models were established to carry out the multi-parameter analysis. The influence rule of the parameters is revealed and the reasonable value range is given, namely. The thickness of channel steel ranges from 1.5 mm to 2.5 mm, the thickness of corrugated steel plate ranges from 1.5 mm to 2.5 mm and the aspect ratio goes from 0.8 to 1.2, and the axial compression ratio of frame column should not exceed 0.3. Finally, the shear-carrying calculation formula is proposed, and the reliability of the formula is verified by comparing formula calculation results with FEA results, whose maximum error is within 15%.