Behavior Of Beam-column Joints Research Articles

Experimental study on seismic behavior of reinforced concrete exterior beam-column joints under varying axial load

The majority of low-cycle loading tests on reinforced concrete (RC) beam-column joints were currently conducted under constant axial loads. During earthquake shaking, the axial load on the joints fluctuates due to the overturning moment and vertical ground vibration. Particularly in exterior beam-column joints, where beam shear occurs on only one side, the range of axial load variation is significantly larger. To elucidate the impact of varying axial loads on the seismic performance of exterior beam-column joints, low-cycle loading tests were conducted on four groups of full-size beam-column subassemblage specimens. Two identical specimens from each group underwent low-cycle loading tests with constant and varying axial loads, respectively. Based on the experimental findings, this paper examines the differences in cyclic behaviors among comparison specimens, focusing on damage characteristics, joint shear strength, stiffness degradation, displacement ductility, and longitudinal bar slip. The study suggests that compared to specimens subjected to constant axial loads, the comparison specimens exhibit variations in load-carrying capacity corresponding to the fluctuations in axial load. Furthermore, varying axial loads accelerate post-peak stiffness and strength degradation, leading to reduced ductility. Additionally, specimens in one of the comparison groups exhibited different failure models when subjected to varying axial loads and constant axial loads, specifically beam failure and joint failure, respectively. Numerical simulations of the corresponding beam-column subassemblages were conducted on the Opensees platform to elucidate how the two axial loading methods affect the transformation of failure modes. A subsequent parametric study focusing on the axial compression ratio was performed to further explore the impact of varying axial loads on the seismic behavior of beam-column joints.

Investigation on effect of ECC coverage condition on seismic behavior of beam-column joint

There is a renewed interest around the world to do fundamental research on novel materials to enhance the overall response of structures under seismic loading. Engineered cementitious composite (ECC) is a special class of concrete with good ductility, which is widely adopted in engineering structures. In this paper, the seismic behavior of beam-column joints incorporated with ECC materials is numerically and experimentally investigated. A database containing available related test results in literature is collected and analyzed to investigate the relations between ECC coverage area and failure characteristics. An interior and an exterior beam-column joint with ECC adopted in the joint region are prepared and tested in this study. The effect of ECC coverage area on the overall joint seismic response is analyzed through a validated finite element model. A modified strength hierarchy analysis is proposed and conducted to consider the application of ECC on the joint. Based on the analytical investigation, the weakest structural element in the joint region is found. The strength hierarchy analysis results have a good correlation with the experimental failure pattern, which shows a potential application as a preliminary analysis to evaluate ECC joint failure mechanisms under seismic loading.

An experimental study for effectiveness of steel fibre reinforced exterior beam-column joints under cyclic resistance

An ability of the structure to sustain levels of inelastic deformation, implicit in ductility values, is dependent on the material and detailing used. In order to achieve this high percentage of lateral reinforcement in the core of the joint is needed; which lead to reinforcement congestion and construction difficulties. In this paper, the behaviour of beam-column joint was investigated for different variations in spacing of lateral reinforcement in critical region. This increased spacing of lateral hoops reduced the reinforcement conjunction and addition of steel fibre reinforced concrete (SFRC) for same region help to remove deficiency due to removal of lateral reinforcement. The steel fibre volume fraction of 2% was used in critical region. Test results of six one-third scaled beams-column joints of reinforce concrete frame are presented to study the influence of steel fibres for effective reduction of lateral hoops in joint region. The experimental investigations also incorporate the evaluation of parameters such as ultimate strength, energy dissipation, ductility, stiffness, specific damping capacity and crack patterns. An experimental result demonstrated that SFRC beam-column joint perform satisfactorily and showed enhancement in all above properties. The behaviour of beam-column joint also showed that the additions of fibre in critical region provided necessary confinement and ductility after reduction in lateral hoops.

Experimental study on the structural behavior of exterior precast concrete beam-column joints with high-strength steel bars in field-cast RPC

To enhance the seismic performance of conventional precast concrete frame structures, this study introduces a novel precast high-performance concrete frame beam-column joint. We designed and conducted experiments on two full-scale precast concrete frame beam-column exterior joints, varying the presence of L-shaped steel reinforcement at the bottom of the beam-column joint. The findings reveal that the load-bearing capacity, hysteresis characteristics, stiffness degradation, and energy dissipation capacity of both joints significantly improve when using reactive powder concrete (RPC) poured into the joint connection area and L-shaped steel at the beam-column junction. A finite element model for these joints was further developed and validated based on the experimental data. Additionally, a parametric study was conducted to assess the impact of axial compression ratio and spacing of hoop bars in the joint area on joint behavior. Using an experimental fitting approach, a tri-linear skeleton curve model for the joints was established, offering a more precise representation of stress and deformation characteristics at each stage. The hysteretic curve generated from this restoring force model closely matches the experimental data, demonstrating the model’s ability to accurately depict the hysteretic behavior of beam-column joints in precast RPC/RC composite frames.

The influence of reverse loading sequence on the behaviour of beam-column joints

The formation of plastic joints in the reinforced beam-to-column joint is influenced by a number of factors. The behaviour and location of this joint is of major importance since it defines the overall performance of the rigid framework when subjected to loading. Mandated by the majority of codes and standards, the strong-column weak-beam philosophy is used and recognized by the formation of this joint in the beam. This study looked into the effect of reverse loading to the behaviour of plastic joints as compared to a monotonic loading protocol. The study analysed the load-deformation behaviour and ultimate load carrying capacity while additional information is collected through visual observation on the failure and cracking pattern. The study concluded that the reverse loading negatively influenced the load carrying capacity, but negligibly affected the overall behaviour of the joint.

Review on Analysis of RCC beam, Column Joint and RCC Shear wall using FRP strengthening on Ansys Software

Abstract: After occurrence of recent earthquakes in the most of world parts, scientific committees for reducing natural disasters and research centers declared based performance design, investigation faults, retrofitting, rehabilitation, new researches are related to strengthening of structures, notice performance, importance of structure, surface of earthquake levels, considering economic and feasibility. One of streningthening method of RC frame is using FRP laminates. Beam and column where intersects is called as joint or junction. The different types of joints are classified as corner joint, exterior joint, interior jointetc. on beam column joint applying quasi-static loading on cantilever end of the beam. and study of various parameters as to be find out on corner and exteriorbeam column joint i.e. maximum stress, minimum stress, displacement and variation in stiffness of beam- column joint can be analyzed in Ansys software (FEM Software) RC shear walls are considered one of themain lateral resisting members in buildings. In recent years, FRP has been widely utilized in order to strengthen and retrofit concrete structures. Significant experimental research has been conducted over the past three decades on hysteretic behavior of beamcolumn joints of RC frames under cyclic displacement loading. The various research studies focused on corner and exterior beam column joints and their behavior, support conditions of beam-column joints. Some recent experimental studies, however, addressed beam-columnjoints of substandard RC frames with weak columns, poor anchorage of longitudinal beam bars and insufficient transverse reinforcement. the behavior ofexterior beam column joint is different than the corner beam column joint.

Seismic Resistance Evaluation of Reinforced Concrete (RC) Exterior Beam-Column Joints with and without GFRP under Quasi-static Lateral Cyclic Loading by Adopting Experimental Analysis

The beam-column joint is an important component of Reinforced Concrete (RC) structures because its design and detailing are critical to the safety of these structures under seismic loading. In recent decades, structural behaviour of beam-column joints has been widely explored. To better understand the behaviour of beam-column joints, researchers have conducted experiments and provided analytical and experimental solutions. The seismic behaviour of beam-column joints with and without Glass Fibre Reinforced Polymer (GFRP) when subjected to quasi-static lateral cyclic loading was compared in this research using two specimens. The first specimen is a typical RC exterior beam-column joint without GFRP while the second specimen is RC exterior beam-column joint that is pre-installed with Glass Fibre Reinforced Polymer (GFRP) using Near-Surface Mounted (NSM) technique. The specimens were evaluated to a drift of 2.0% under quasi-static lateral cyclic loading. There were two cycles in each drift. Based on the amplitudes of both specimens, it can be seen that the amplitude of beam-column joint with GFRP is lower than the beam-column joint without GFRP. This suggests that the presence of GFRP reduces the intensity of the loading. This study also discusses the energy dissipation and equivalent viscous damping on both specimens. During the experiment, each crack, void between the concrete, and spalling of concrete fragments were carefully monitored. Visual observation during the experiment shows that severe cracking is evident on the inner part of the structure in both specimens. Therefore, a new location of GFRP-NSM would be suggested for a future experiment.

Behavior of beam-column joints with high performance fiber-reinforced concrete under cyclic loading

A total of eight interior beam-column joints with high performance fiber-reinforced concrete (HPFRC) were fabricated and tested to investigate their seismic behaviors in terms of failure mode and load-carrying capacity. The effects of stirrup ratio in the joint zone, strength of reinforcement in the beam, axial compression load level, web reinforcing bars, and vertical reinforcing bars across the joint zone on the shear capacity of HPFRC beam–column joints were analyzed. A formula for calculating ultimate shear strength of HPFRC joints was established. It was demonstrated that interior beam-column joints with HPFRC have good load-carrying capacity, which were attributed to the superior mechanical properties of the HPFRC. After cracking, the tensile strain of the stirrups increased in the middle of the vertical length of the joint and decreased in the upper and lower parts. The ultimate bearing capacity of the specimen increased by 11.1% when the column axial load increased from 0.3 fcAc to 0.5 fcAc (where fc is the compressive strength and Ac is the column area). However, when the column axial load increased from 0.5 fcAc to 0.6 fcAc, the ultimate bearing capacity of the specimen is almost unchanged. The stirrup ratio of the joint zone increased from 0 to 2.90%, and the ultimate bearing capacity of the joint increased by 21.34%. The non-corner vertical reinforcement in columns and the stirrups in joint zone improve the load-carrying capacity of beam-column joints with HPFRC.

Impact behavior of beam-column joint with geometric imperfections at weld root

This study numerically investigates dynamic response of welded beam-column joint with different weld imperfections at weld root. The imperfections at weld root, such as incomplete root penetration, shrinkage groove and root concavity, are considered in this study. The size and shape of these imperfections are determined in accordance with ISO 5817 code. Numerical model of welded beam-column joint with imperfections is developed and calibrated by the test results of welded beam-column joint without imperfection under impact load as well as the numerical results of butt-welded joint with grinding profile under static load. The factors of the imperfections, such as the distribution and length of imperfections and the weld quality levels are considered to investigate their effects on the damage mode, dynamic response, and energy dissipation of welded joints subjected to impact loads, as well as the post impact behavior of the joint. Parametric study is carried out to investigate the effect of impact velocity and impact mass on welded joint with different root imperfections. The effect of different weld imperfections on the energy dissipation of joint is also investigated. The most vulnerable form of root imperfection is identified by comparing the joints with different imperfections in terms of damage mode, dynamic response and energy dissipation.

Analytical and Experimental Study on Flexural Behavior of Beam-column Joint with Addition of Polypropylene Fibers

Key scope of this research is evaluation of actions of beam to column joints under the impact load acting on it. The beam-column joints, a common area between frame beams and columns. It is the most critical zone to ensure the global response of such momentary resistance structures. Several approaches have been attempted over the years by many civil engineers and practitioners to improve the deficiently thorough joint in between beam and column. The highest bending moment and shear forces in the framed structures are at the junction area. As a result, that joint between beam and column is one of a collapse zone. Joint in outer is more important among the beam-column joints. The effect may be caused by a weight falling on the design object or possibly falling off the design object and hitting the hard surface. In this work, an emphasis has been made to understand the joint vulnerability against impact loads and its behavior is analyzed using the ANSYS software. From this experimental program observed that, impact resistance in RCC beam to column joints can be improved by improving stiffness by added polypropylene fibers and energy absorption can also be improved.

Seismic behavior of beam-column joints with different concrete compressive strengths

This study experimentally evaluated the seismic performance of beam-column joints with different compressive strengths. A total of three exterior beam-column joints were fabricated and tested under reversed cyclic loading. The primary test parameter was the ratio of the concrete compressive strengths of the column and beam. The crack patterns and failure mechanisms, load-displacement relationships, envelope curves, stiffness degradation, energy dissipation, behavior of longitudinal reinforcement in the beam, and transverse reinforcement in the joint were analyzed in detail. Experimental results revealed that the overall seismic performance of the beam-column joint was improved as the compressive strength of the concrete in the column increased. In particular, the specimens with the column-to-beam concrete compressive strength ratios of 2.3 and 3.2 showed over 9% greater joint shear strengths than the one with a monolithic joint. However, the strains of transverse reinforcement in the joint also increased with a high ratio of the concrete compressive strengths of the column and beam. Therefore, when the compressive strength of the column concrete is greater than that of the beam concrete, it is recommended that additional transverse reinforcements be incorporated in the joint region.

Numerical analysis on seismic behavior of beam-column joint with different cement-based materials

Under cyclic loading conditions, the ductility of frame beam-column joints, which can be evaluated by the displacement ductility coefficient ( μ), is strongly affected by the axial load ratio ( n). Due to the high toughness of engineering cementitious composites (ECCs), the normal concrete can be replaced giving better joint ductility. However, the limit values of n for reinforced ECC (R-ECC) joints have not been clarified. Therefore, T- and cross-shaped reinforced concrete (RC) and R-ECC joint finite element models were established and analyzed under n values. The results indicated that the seismic performance of the joints, including μ, equivalent damping coefficient ( ξ eq), and secant stiffness ( K i) were strongly dependent on n. μ and ξ eq became inversely proportional to n when n was over 0.5. The RC and R-ECC joint ductile failure could occur when n was in the range of 0.3–0.7 and 0.3–0.9, respectively. The joint brittle failure occurred in RC and R-ECC joints when n was over 0.7 and 0.9, separately. Under the same n and load history, the maximum value of μ of R-ECC joints increased by 33.7% and 27.9% for T- and cross-shaped joints separately compared to that of RC joints. It is suggested that the n values for RC and R-ECC joints should not exceed 0.7 and 0.9, respectively.

Cyclic behaviour of beam-column joints made of crumb rubberised concrete (CRC) and traditional concrete (TC)

Crumb rubberised concrete (CRC) is a sustainable material that recycles rubber particles from end-of-life tyres as partial fine aggregates in concrete. To promote the applications of CRC in building structures, this paper presents an experimental study on the cyclic behaviour of beam-column joints from both CRC and traditional concrete (TC) frame structures. CRC with 15% rubber content by sand volume was employed. Three full scale CRC joint samples and one full scale TC sample were tested. Varying axial loads were applied on the top of columns and anti-symmetrical low-frequency cyclic loads were applied at the two beam ends. The failure modes, hysteretic behaviour, stiffness degradation, bearing capacity degradation, shearing capacity, displacement ductility and strain response of CRC and TC joints were investigated and compared. Both CRC and TC joint samples reached their ultimate loads due to shear failure. When CRC and TC were with similar strengths, the first crack loads, yielding loads, ultimate loads and ultimate displacements for TC and CRC joints at the same axial compression ratios were comparable with slight differences within 5%. However, CRC joints exhibited an improved energy dissipation ability by up to 10.4% over TC samples.

RC columns strengthened by steel caging: Cyclic loading tests on beam-column joints with non-ductile details

Beam-column joints suffer intense damage from seismic events and are the cause of many buildings collapsing. These zones present complex behaviour under cyclic loads, including tensile-compression cycles, which make reinforcement adherence worse and cause severe cracking in concrete. Although columns can be strengthened by various methods (e.g. concrete jacketing, fibre-reinforced polymers and steel jacketing-caging), beam column joints require complex systems being applied, but are not always effective. In Europe, fitting steel caging around columns is one of the most frequently used techniques, although its effectiveness against seismic events requires further study. The aim of this work is to analyse the behaviour of beam-column joints strengthened by steel caging subjected to cyclic loading, for which an ambitious experimental campaign was carried out on seven full-scale steel-caged specimens with a variety of strengthening solutions at joints. The results provide insight into the complex behaviour of joints with columns strengthened in this way, used as the basis for practical recommendations for engineers and architects who have to routinely retrofit structures against seismic events.

An experimental and analytical investigation of reinforced concrete beam-column joints strengthened with a range of CFRP schemes applied only to the beam

This paper investigates the experimental and analytical behaviour of beam-column joints that are subjected to a combination of torque, flexural and direct shear forces, where different Carbon Fibre Polymer (CFRP) strengthening wraps have been applied only to the beam. These wrapping schemes have previously been determined by the research community as an effective method of enhancing the torsional capacities of simply supported reinforced concrete beams. In this investigation, four 3/4-scale exterior beam-column joints were subjected to combined monotonic loading; three different beam wrapping schemes were employed to strengthen the beam region of the joint. The paper suggests a series of rational formulae, based on the space truss mechanism, which can be used to evaluate the joint shear demand of the beams wrapped in these various ways. Further, an iterative model, based on the average stress-strain method, has been introduced to predict joint strength. The proposed analytical approaches show good agreement with the experimental results. The experimental outcomes along with the adopted analytical methods reflect the consistent influence of the wrapping ratio, the interaction between the combined forces, the concrete strut capacity and the fibre orientation on the joint forces, the failure mode and the distortion levels. A large rise in the strut force resulting from shear stresses generated from this combination of forces is demonstrated and leads to a sudden-brittle failure. Likewise, increases in the beams’ main steel rebar strains are identified at the column face, again influenced by the load interactions and the wrapping systems used.

Numerical and analytical modeling of seismic behavior of beam-column joints retrofitted with ultra-high performance fiber reinforced concrete

Strengthening the seismic deficient beam-column joints (BCJs) in reinforced concrete structures is mostly adopted to avoid any devastating consequences of high-intensity earthquakes. To evaluate the performance of BCJs against seismic action, experimental testing of BCJs under cyclic loading is a time-consuming and cost-intensive work due to the requirement of large-scale instrumentation and testing. This paper reports a study on the numerical and analytical modeling of the seismic behavior of BCJs built using normal concrete and retrofitted with ultra-high performance fiber reinforced concrete (UHPFRC). A computer simulation using the nonlinear finite element (FE) method was developed considering a concrete damage approach in modeling both types of concrete, i.e., normal concrete (substrate) and UHPFRC (overlay). The interface between the substrate and overlay was modeled as a cohesive element. The properties of this bonding interaction were experimentally evaluated based on the results of the push-out test. The simulation results benchmarked with the experimental data of a previously published study. It was found that the proposed FE model is in good agreement with the experimental behavior of seismically tested specimens in terms of global load–displacement, ultimate load, and damage evolution. In addition, the use of surface-to-surface cohesive elements played an important role in the bonding interface under cyclic loading. Additionally, an analytical model was developed to predict the shear capacity after retrofitting the BCJ. The results obtained by using the analytical model were consistent with the corresponding experimental values. Finally, a parametric study was carried out to examine the effects of the thickness of UHPFRC jacketing and longitudinal reinforcements ratio of the beam on the performance of the retrofitted BCJs.

Effect of profiled decking on composite beam-column joints with end-plate bolted connections under column-removal scenario

In the design of structures against progressive collapse, component-based modelling has been applied to simulate the behaviour of beam-column joints under column-removal scenarios. However, only limited studies consider the effect of profiled decking on load-carrying capacity of composite joints. In composite frames, the direction of profiled sheeting is parallel to the main beam but runs transverse to supporting secondary beams. This study aimed to develop component-based models that can predict behaviour of beam-column joints with either longitudinal or transverse profiled sheeting so that engineers can design joints on both the main and the secondary beams against progressive collapse. Two composite beam-column joints with extended end-plate (EEP) connections and two with partial-depth end-plate (PEP) connections were tested under a central-column-removal scenario. For each connection type, both longitudinal and transverse profiled sheeting directions were studied. Two welded T-stub specimens were tested to obtain the behaviour of component properties. Innovative component models for concrete components and for welded T-stubs in extended end-plate joints were developed. The proposed component-based models gave acceptable predictions of composite joint behaviour. It was found that extended end-plate connections had better load-carrying capacity but lower joint rotation capacity than partial depth end-plate connections. For the same connection type (either EEP or PEP), the maximum loads of specimens with transverse sheeting were only 70% of those with longitudinal sheeting.

Experimental investigation on rcc external beam-column joints retrofitted with basalt textile fabric under static loading

The role of a beam-column joint is very vital in RCC framed structures. Most of the structural collapses due to earthquakes have been initiated by the failure of the beam-column joints and therefore understanding the behavior of beam-column joints is important. Large numbers of retrofitting techniques are being adopted worldwide to strengthen the beam-column joint. This paper presents the results of the first phase of experimental investigation on retrofitting of an external beam-column joint by externally bonded basalt fabrics. Eleven specimens of external beam-column joints using strong column-weak beam concept were prepared and tested under static loading conditions. Three specimens were tested and considered as control specimens. Remaining eight specimens were subjected to an induced damage by preloading them up to 50% of ultimate load recorded in control specimens. The damaged specimens were then retrofitted with basalt fiber fabric adopting four different configurations. The retrofitted specimens were tested for their ultimate capacity and the outputs were compared with that of the control specimens. The test results show that basalt textile reinforcement enhances the performance of the retrofitted specimens.

Composite steel beam is commonly used element in multistory steel buildings today. The composite action between the concrete deck and the steel beam reduces both steel weight and deflection, accordingly, enhance floor economy and serviceability. Many earlier researches were carried out to optimize the design of the composite steel beams under both static loading and dynamic behavior. None of these

In many situations, it is necessary to have a beam web opening in the plastic hinge location. However, very limited studies investigated the behavior of reinforced concrete (RC) beam-column joints with nearby beam web openings. A previous study was conducted for investigating the behavior of beam-column joints with unreinforced nearby web opening. In this study, the effect of adding additional reinforcing around a nearby web opening on the seismic behavior of RC exterior Beam-Column joints is being investigated. Nine full-scale beam-column joints were tested, four joints had an unreinforced opening, while five joints had reinforced opening. The behavior of the beam-column joints is described in terms of maximum resisting load, deflection, energy dissipated, and stiffness degradation. The behavior was significantly affected by the nearby opening. The increase in opening width and the reduction in the distance between the opening and the column resulted in decreasing the strength and ductility of the RC beam-column joint. However, adding additional reinforcement improved the behavior. Thus, it is recommended to provide additional reinforcement all around the opening.

In many situations, it is necessary to have a beam web opening in the plastic hinge location. However, very limited studies investigated the behavior of reinforced concrete (RC) beam-column joints with nearby beam web openings. A previous study was conducted for investigating the behavior of beam-column joints with unreinforced nearby web opening. In this study, the effect of adding additional

the paper presents an efficient scheme for a Nonlinear PID (NPID) controller to improve the dynamic response of the Electric Vehicle (EV). The objective of the proposed controller is to track accurately the reference speed selected by the driver of the EV. A MATLAB/Simulink model is established and validated for the considered EV to study the system performance. The proposed NPID controller has been investigated by comparing it with the traditional PID controller. The optimal parameters of Both the NPID and PID controllers were obtained using the Harmony Search (HS) optimization technique based on a cost function. The desired rise time, settling time, steady-state error, and overshoot have been taken into account in the cost function. Two tests were performed, the first test was implemented at fixed reference speed while the second one was carried out at a staircase command of reference speed. The simulation results can be summarized as follows: in the first test, the NPID controller reaches the steady-state speed at 38.12 seconds while the PID controller stabilizes at 44.68 seconds. Moreover, the NPID controller has a 0.5% steady-state error however, the PID controller has a 4% steady-state error. Besides, the second test shows that the NPID controller can decrease the root mean square of error by 30.1% compared to the PID controller. Lastly, the proposed NPID controller can enhance EV performance significantly.