Concrete Frame Structures Research Articles

Post-Fire Seismic Performance of Concrete-Filled Steel Tube Frame Structures Considering Soil-Structure Interaction (SSI)

Currently, reinforced thin-walled irregular steel tube concrete frame structures have been applied in engineering, but there are few researches on the seismic performance of this type of structures after fire. The seismic performance of structures after fire is generally carried out based on rigid foundation conditions. Therefore, it is of certain engineering and theoretical value to study the seismic performance considering the SSI (soil–structure interaction) in this paper. ABAQUS is employed to establish the finite element models of the reinforced thin-walled irregular steel tube concrete frame structure considering the SSI after a fire. The paper analyzes the impact of different site conditions and fire durations on the structural natural vibration period, maximum acceleration, inter-story shear force, and maximum inter-story displacement angle. The results show that the consideration of the SSI increases the basic natural vibration period of the structure by 10–30%. The softer the soil and the longer the fire duration, the more significant the increase. For harder soil, lower seismic intensity, and shorter fire duration, the acceleration assigned to the structure and foundation after considering the SSI is smaller than the results assuming a rigid foundation. The change in inter-story shear force is mainly determined by the acceleration of the structure and foundation. The inter-story displacement angle increases when considering the SSI, and the increase is more significant with softer soil, larger seismic wave acceleration amplitude, and longer fire duration.

Numerical Analysis of Hybrid Fibre-Reinforced Concrete Beam-Column Joint

Beam-column joint is the most vulnerable location of a moment-resisting reinforced concrete frame structure. The joint region experiences the maximum shear stress both in vertically and horizontally which is generated due to the shear transfer mechanism from the adjoining beams and columns. The shear capacity and bond stress capacity are the two major factors affecting the strength of a joint core in RC structure. An important discovery recently is the ductile behaviour of the whole structure under repeated loading. The behaviour of the concrete beyond elastic limit which is in the concrete hardening zone can drastically influence the ductility of the concrete. The non-linear stress-strain behaviour after the onset of the initial crack and up to ultimate compressive strength plays an important role in improving ductility. Beyond the ultimate compressive strength, concrete will undergo softening which is neglected in this study as once concrete reaches ultimate stress it is unsafe for service. This material ductility can be fulfilled with the application of high-strength fibres with ductile behaviour. However, the hybridization of two or more fibres can incorporate two different characteristics of the fibre used. The use of ordinary-grade of concrete moreover reduces the shear-resisting capacity of the joint. A hybrid mix of hooked-end steel fibre with basalt fibre and crimpled steel fibre with polypropylene fibre are used with a volume fraction of 1% to 1.4% of the concrete. In this study, ordinary M25 grade concrete and fibre mixed M25 grade concrete is employed under static and cyclic loading. The laboratory tests are also conducted to evaluate the compressive strength, split-tensile strength, and flexural strength of the hybrid mix fibre-reinforced concrete at the age of 28th days. Five full-scale models of the beam-column joint are designed as per the Bureau of Indian Standards. Numerical models of concrete and steel reinforcement are developed. Numerical analysis is carried out using finite element software ANSYS-v21. The behaviours of the beam-column joint are observed under static as well as cyclic loading. Crack patterns, first crack load, initial displacement, ultimate load, and ultimate displacement are observed under static conditions. And under cyclic loading, hysteresis load vs displacement, energy dissipation, and stiffness degradation are observed. The hybridization of hooked steel with basalt fibre gives better results in mechanical strengths and the hybrid effect of crimpled steel with polypropylene fibre gives better results in mechanical strengths. And also under numerical study, the above specimens show an improvement in energy dissipation capacity. Keywords beam-column joint, hybrid fibre reinforced concrete, numerical concrete model, ANSYS, static, reverse cyclic, energy dissipation, stiffness, crack

Evaluation of Damage Severity and Strength of Structural Member Using Macro‐Molecular PZT Sensor

AbstractThe structural health of various engineering systems has been easily monitored using macromolecular piezoelectric ceramic lead zirconate titanate (PZT) based electromechanical impedance (EMI) technique. It is in need to study the evaluation of various levels of damage and the present strength of structural systems to enhance the life of structures. Once damages occur, due to continuing usage they usually propagate in certain directions. Moreover, the increase in the severity of damages may lead to failure of the structural components or even the whole structure. Interaction between structure and PZT, which is found effective in EMI technique, is to identify effective damage detection. The macro‐molecular PZT's self‐actuating and sensing properties are utilized by the electromechanical impedance (EMI) method. The higher modes of vibration are locally activated by the local application of an AC source on the PZT transducers attached to the host structure. In this paper, the EMI technique using surface‐bonded PZT transducers is employed to obtain the structural health signature. The experiment is carried out on a real‐size concrete frame structure subjected to artificial damage to identify and locate the damages using frequency variations, and the severity is checked using extracted equivalent parameters; the damage index. This method also can identify hair‐like cracks at an early stage, which explains how it can shield the building from serious failures.

Seismic performance of structure equipped with a new rubber bracing damper system

Nowadays, vibration energy absorption devices are widely implemented in many buildings subjected to severe vibration due to natural hazards, such as earthquakes, strong winds, and typhoons. Recently, viscous dampers have been commonly used in many structures as the most conventional damper type. However, the high maintenance cost resulting from oil leakage from cylinder seals has prompted researchers to seek an alternative system to viscous damper systems. Therefore, the main aim of this research is to develop a new rubber bracing damper (RBD) system by implementing high damping rubber material as a viscoelastic material to be installed in framed structures as diagonal bracing members. This will help dissipate vibration effects on the structure. To achieve this, the initial design for the RBD device has been developed, and finite-element simulation has been conducted to evaluate the behavior of the proposed RBD under various dynamic loading conditions. To define the viscoelastic material properties in finite-element modeling, high damping rubber material has been produced and experimentally tested to determine the numerical model of the material. Subsequently, the test data were utilized to develop the analytical model of the RBD device, and its performance was evaluated by applying cyclic loads and conducting nonlinear analysis. Furthermore, a series of cyclic dynamic tests with various displacement amplitudes and frequencies have been conducted on the prototype of the RBD device based on the finite-element results. Finally, to analyze the dynamic behavior of the structure equipped with RBD, a finite-element model of a three-story reinforced concrete frame structure furnished with RBD dampers has been developed. The response of the structure has been evaluated under seismic loads, and a parametric study has been conducted to investigate the response of the structures with various rubber properties. The numerical analysis results indicated that the implementation of the RBD device leads to a reduction in the occurrence of plastic hinges and lateral displacements of the structure by up to 69%. This demonstrates the efficiency of the RBD device in diminishing the seismic load effect on the structure’s response.

Dynamic progressive collapse response of 3D monolithic precast concrete frame structures considering slab effects

The robustness of precast concrete frame structures to withstand extreme events like explosions, impacts, fires and terrorist attacks has attracted growing attention. With the understanding of the static progressive collapse performances of 2D precast frame structures, research on the dynamic responses of 3D precast frame structures is pressing and high in demand. To evaluate the influence of floor slabs on dynamic progressive collapse responses of 3D precast concrete frame structures, an experimental program consisting of a beam-column (PC) and a beam-slab-column (PCS) specimens was first designed, followed by the analysis of the working mechanisms to resist progressive collapse. The modeling techniques for 2D PC and PCS substructures were then proposed and validated using the test results. The numerical strategy was further extended to simulate the dynamic progressive collapse responses of 3D PC- and PCS-frame structures. Results show that, under various column loss scenarios, floor slabs significantly improve progressive collapse resistances of 3D frame structures. Moreover, it reveals that the floor slabs have a remarkable effect on reducing the nodal displacements and the dynamic amplification factors.

Proposal for a novel technological damper system (TDS) for the retrofit of reinforced concrete frame structures

Considering the severe earthquakes that have occurred worldwide, it has been observed that even buildings which are constructed in compliance with the seismic regulations, have suffered heavy damage or collapsed. Similarly, in earthquake on February 6, 2023, in Kahramanmaraş, Turkey, many old and new structures were damaged or even collapsed. This situation has compelled researchers to focus on the most current and technological applications for earthquake protection. In the latest research topics, there has been a growing emphasis on the impact of new technological systems targeted at improving the seismic performance of structures constructed with reinforced concrete systems, given the notable occurrence of collapsed buildings with such structural systems in this earthquake. In this study, the developed Technological Damper System (TDS) was employed to enhance the earthquake performance of reinforced concrete structures. TDS is a versatile and adjustable friction-type damper. For this reason, two identical ½ scaled reinforced concrete frames were fabricated for the study, one representing a traditional structure as a reference frame (REF), and the other a frame with the TDS device. After applying quasi-static cyclic tests to the frames, the force-displacement, and force-rotation relationships, as well as energy dissipation capacities were determined for both frames. In addition, the damage conditions of the columns during the tests were assessed based on the plastic rotation limit conditions outlined in Turkish Building Earthquake Code (TBEC 2018). As a result, the frame retrofitted with the TDS device exhibited a significant increase in horizontal load-carrying capacity, ranging from 42.04% to 75%, when compared to the REF. Additionally, it was observed that energy consumption increased between 85% and 220%. The REF reached significant damage levels at 1% and 2% story drift ratios and an advanced damage state at about 3%, in accordance with TBEC 2018. Finally, the behavior of the frame retrofitted with TDS considerably improved according to REF and it reached a significant damage state at 3% story drift ratio.

Influence of rupture velocity on risk assessment of concrete moment frames: Supershear vs. subshear ruptures

The possibility of ground motions propagating at speeds greater than the Rayleigh wave speed was accepted not long ago, and thus studies on them are limited. These supershear motions are believed to damage specific kinds of infrastructure, and thus studying the risk associated is important. As a part of this investigation, we use state-of-the-art tools from the Natural Hazards Engineering Research Infrastructure to estimate normalized economic losses and injuries, by considering one particular building type and occupancy category listed in HAZUS-MH. Faults of similar dimensions are shown to replicate subshear and supershear earthquake instances with four groups of station points parallel to the fault and four more perpendicular to the fault. Both fault parallel and fault normal components of ground motion are stimulated. The economic loss % and injury is standardized in metrics of repair cost and population respectively and is estimated along with the associated uncertainty for 3, 6 and 9-story commercial concrete moment frame structures. Inclusion of complex phenomena such as supershear earthquake events in evaluating economic losses and risk will contribute to the United Nation Office for Disaster Risk Reduction (UNDRR) vision of disaster-resilient development goals.

Percentile influence of beam column cross-sectional design on progressive collapse potential of low-rise reinforced concrete framed structure

Percentile influence of beam column cross-sectional design on progressive collapse potential of low-rise reinforced concrete framed structure

Damage analysis of a pseudoclassic reinforced concrete frame structure under the action of the Ms 6.8 Luding earthquake in China

Reinforced concrete (RC) moment-resistant frame structures are very commonly used worldwide. However, previous earthquakes have revealed the occurrence of strong beam–weak column (SBWC) failure, causing heavy human casualties and economic losses. This study analyzed the SBWC failure mechanism in RC frame structures with the pseudoclassic construction named "Que Ti" near the top of a slope topography, based on the author's recent investigation of the Ms 6.8 Luding earthquake in China. Eight refined finite element models (FEMs) were developed to simulate and analyze the influence of slope topography, pseudoclassic construction, and some structural characteristics on structural damage during an earthquake. Furthermore, discussions on using column-to-beam flexural strength ratios (CBFSRs) to mitigate SBWC failure are presented. The results demonstrated the proposed FEMs effectively simulated the performance of the pseudoclassic structure, especially the SBWC failure mode, as validated by their consistency with the observed structural damage during the earthquake. Moreover, it revealed that structures closer to the slope top experienced amplified ground motions during earthquakes, resulting in more severe damage. In addition, the Que Ti and infill walls increased the vulnerability to column damage and maximum requirement for the column shear force. Finally, to achieve the design objective of a strong column–weak beam (SCWB), the CBFSR should be at least increased to 1.8 for this pseudoclassic RC frame. This ensures a probability of the SBWC failure mode of less than 17% (meet less than 20% of recommendations) and proportion of the beam plastic energy dissipation exceeding 80% of the total plastic energy dissipation. The findings of this study are significant for enhancing seismic design and preventing earthquake disasters for the pseudoclassic structure.

Shaking table tests of sliding‐prone blocks subjected to unidirectional and bidirectional ground and floor motions

AbstractFreestanding museum collections with low friction coefficients and high aspect ratios may be damaged due to excessive sliding displacements during earthquakes. However, several key issues have not been adequately addressed, such as the friction and sliding behavior of museum collections under actual conditions. Unidirectional and bidirectional shaking table tests were conducted to determine the maximum sliding displacements (MSDs) of a freestanding glass block on sandpaper, which had the lowest friction coefficient among forty‐two contact interfaces in slow‐pull tests. Fourteen far‐field and fourteen near‐fault pulse‐like ground motion records were applied with peak ground accelerations (PGAs) of the major components scaled from 0.05 to 0.6 g. Shaking table tests of a full‐scale three‐story reinforced concrete frame structure containing glass blocks were carried out. Seismic fragility curves corresponding to the sliding failure of the glass block were generated based on the experimental results considering the friction coefficient uncertainty. The results show that the influence of the bidirectional interaction on the MSD is more significant for near‐fault pulse‐like ground motions than far‐field ground motions. For a specific ground motion record, the sliding displacement of the glass block may not increase with the increase of the PGA or peak floor acceleration due to the friction coefficient uncertainty, but this has a negligible influence on the fragility. A clearance around sliding‐prone museum collections with friction coefficients larger than 0.20 is recommended to ensure that the probability of exceedance is lower than 5%.

Global building life cycle assessment: Comparative study of steel and concrete frames across European Union, USA, Canada, and Australia building codes

The construction industry has one of the worst carbon footprints among the major industries and accounts for 39% of the world’s total greenhouse gas emissions. One of the main determinants of the carbon footprint of a building is the type of frame used in its structure. The most commonly used types of structural frames are steel and concrete frames, each having its own advantages and drawbacks. This study estimates and compares the carbon footprint of two buildings designed with a steel frame and a concrete frame, respectively, based on the building structural design codes of the European Union (EC), USA (ACI, AISC), Canada (CSA), and Australia (AS). The primary objective of this study is to conduct a comprehensive comparison of carbon emissions from these buildings. The focus extends beyond operational emissions to include an assessment of embodied emissions using the life cycle assessment (LCA) methodology. This comparison aims to gauge the overall emissions of the buildings and also evaluate the impact of major building codes on their carbon footprint. The results show that among the steel frame structures designed based on different building codes, the one designed according to the codes of the European Union has the highest carbon emission (142 kgCO2-eq/m2 floor area), and the one designed based on the Australian code has the lowest carbon emission (119 kgCO2-eq /m2). Among the concrete frame structures, the one designed based on the Canadian codes had the highest carbon emission (221 kgCO2-eq/m2), but again, the structure designed according to the Australian code had the lowest carbon emission (134 kgCO2-eq /m2). Carbon emission estimations for the operational phase showed that, while Canadian Cities exhibit the highest portion of energy consumption, its utilization of a green electricity grid results in the lowest operational carbon emissions. In contrast, Sydney, despite having the lowest energy consumption, exhibits the highest level of operational carbon emissions due to its reliance on coal for electricity generation. The findings of this study can serve as a valuable benchmark for policymakers in various areas. They can identify the shortcomings and advantages of their region's building codes, paving the way for targeted modifications that contribute to achieving a more sustainable built environment in their respective locales.

The role of in situ dynamic tests on model updating of existing R.C. infilled structures

Infill masonry walls are one of the most common non-structural elements worldwide adopted to create external and internal partition walls in reinforced concrete (RC) frame structures. Both in the design of new RC frame buildings and in the assessment of the existing ones, it is common practice to neglect the presence of infill walls that are only considered as added masses and loads. However, as revealed by earthquakes, the performance of this type of building can be significantly affected by the presence of infill walls according to their type and distribution in the plane and along the height. In last decades, often vibration-based tests have been adopted to investigate in-situ the influence of the non-structural elements on the dynamic behavior of buildings. This paper discusses the usefulness of the dynamic characterization of buildings based on the use of ambient vibration tests at different phases of rehabilitation works to highlight the role of internal and external infill walls. The case study is an existing RC framed building designed for gravity loads and containing unreinforced masonry infill walls. Three ambient vibration tests, i.e., on the as built structure, after the demolishment of the internal partition walls and after the partial demolishment of the external infill walls, have been carried out. The 3D finite element model of the building has been successfully updated based on the global modes identified by the in situ tests, pointing out the important role of the non-structural components for this type of building. The experimental tests have also allowed the monitoring of the evolution of the building modal properties during the main phases of rehabilitation works.

РАСЧЕТ ПАРАМЕТРА ЖИВУЧЕСТИ ЖЕЛЕЗОБЕТОННЫХ РАМ СО СЛОЖНОНАПРЯЖЕННЫМИ ЭЛЕМЕНТАМИ

On the energy basis, using the diagrammatic method, the solution of the problem of determining the survivability parameter of the reinforced concrete frame structure of a multistory building with complex-stressed elements under static-dynamic deformation caused by a special impact is obtained. Determination of the parametric load value, at which in the most stressed spatial section at the considered loading mode one of the criteria of the special limit state comes from the system of canonical equations of the extraordinary version of the mixed method. Comparison of the experimental and design survivability parameters gives an assessment of the efficiency and reliability of the proposed design dependencies. It has been shown that with the adopted initial hypotheses, the proposed method for calculating the survivability of frames with complex stressed elements satisfactorily describes the process of their deformation and destruction under the considered impacts.

Analytical and Statistical Analysis of Reinforced Concrete Frame Structure Subjected to Blast Loading

Analytical and Statistical Analysis of Reinforced Concrete Frame Structure Subjected to Blast Loading

Structural assesment and numerical analysis of existing reinforced concrete frame structure

The subject of this study is the presentation of in-situ tests on the existing structure and structural analysis of the Faculty of Political Sciences building at the University of Zagreb which sustained damage in the series of earthquakes that hit Zagreb and Petrinja in 2020, as well as the structural strengthening efforts undertaken thereafter. The load-bearing structure of this mid-20th century building is a reinforced concrete frame system (column-beam). Filling between frames is masonry made of solid bricks. The floor structure is reinforced concrete ribbed slabs, characteristic of the construction period. Structure has a basement and six floors above ground. In-situ testing revealed that the compressive strength of concrete was at least 30.7 MPa, and tensile strength of steel reinforcement to that of B 240. It was determined that that the existing masonry walls did not have sufficient shear resistance due to the degradation of the bonding material. Numerical model was made considering the peak ground acceleration of ag/g = 0.249, and the importance factor of γI = 1.2. The analysis showed that the existing building complied with 19% ag/g of today’s applicable regulations for designing earthquake-resistant structures. The main strengthening included the installation of external steel trusses on both facades connected to the external column or facade frame, thus not affecting the existing floor plan. RC walls were added to side of main building volume in the transvers direction and to the staircase portion in both directions as additional bracing. Since the calculations assumed the behavior of the frame for the existing load-bearing structure of reinforced concrete beams and columns, the joints were additionally reinforced by wrapping them with CFRP fabric to enhance reinforcement, since these areas are very sensitive to seismic action.

Multiscale analysis and application of modified PVA fiber reinforced rubber concrete in frame structures

The paper presents a multiscale analysis of PVA fiber-reinforced rubber concrete modified with KH-560. Through a combined approach of experiments and numerical simulations, the feasibility of applying PVA fiber-reinforced rubber concrete in frame structures is validated. Firstly, utilizing molecular dynamics simulations with MS software, the modification effect of KH-560 on PVA fiber material is explored at the molecular level, confirming its ability to effectively enhance the bonding strength between PVA fibers and rubber concrete. Subsequently, a portal frame structure experiment is conducted, validating the actual strength and stiffness of the material through mechanical performance measurements. Lastly, employing Abaqus finite element software, a numerical simulation of the material's application in concrete frame structures is conducted, analyzing its mechanical response and performance in real engineering environments. The research findings indicate that by fully exploiting the deformation characteristics of PVA fiber-reinforced rubber concrete after modification, the use of this material in structural frameworks can maintain or even slightly increase the load-bearing capacity. This study pioneers new prospects for the application of PVA fiber-reinforced rubber concrete in concrete frame structures, providing a more reliable and secure option for structural engineering practice. It offers concrete and innovative solutions for the sustainable development of actual engineering projects.

6 Şubat 2023 Türkiye Depreminde Hasar Görmüş Betonarme Yapıların Güçlendirilmesi için Alternatif Ferrocement Paneller

Most of the reinforced concrete framed buildings commonly used in developing countries are not secure against earthquakes. Studies on seismic performance of reinforced concrete framed structures showed that; lateral stiffness often needs to be improved. In this study, in order to rehabilitate the structures, performances of ferrocement panels can be used to strengthen the existing hollow brick infill walls such that they act as cast-in-place concrete in fills improving the lateral stiffness is researched. Ferrocement panels are not only to be as light as can be carried by two people easily, but also from the low cost and usefulness against tensional and loads point of view. Previous researches results indicated that strength, stiffness, energy dissipation and story drift characteristics of the reinforced concrete framed building structures can be rehabilitated by the eco-friendly, cost effective and practically applicable seismic retrofitting technique that does not need evacuation of the building with these high-performance ferrocement panels.

Experimental Study on 3D RC Frame Structures with VE Energy Dissipation Braces Using STM32-Matlab-OpenSees Hybrid Test Platform

This study aims to reveal the control mechanism of viscoelastic (VE) energy dissipation braces with strong mechanical nonlinear characteristics on the seismic response of reinforced concrete (RC) frame structures. Firstly, a new STM32-Matlab-OpenSees joint hybrid test platform is developed by introducing OpenSees, which is convenient for structural modeling and fast for structural calculation. The overall architecture and operation of the hybrid test platform are comprehensively analyzed. Then, a series of simulated seismic hybrid tests on three-dimensional (3D) RC frame structures with VE energy dissipation braces under different seismic waves are successfully carried out. Lastly, the hybrid test results of this structure system at different working conditions are compared and analyzed comprehensively. The research results show that the developed platform breaks the boundary limitation that OpenSees relies on the framework software OpenFresco and can only be connected to specific control systems in the hybrid test. Thus, it greatly expands the application scope of flexible configuration controller and actuator categories for the hybrid test platform, and it also provides a good reference value for the establishment and implementation of similar hybrid test platforms. Under the action of various seismic waves, VE energy dissipation braces has good universality for the shock absorption of RC frame structures. The damping control effect and energy dissipation efficiency of VE energy dissipation braces are significantly different under various seismic waves. In the design of RC frame structures with VE energy dispersion braces, it is very necessary to conduct the seismic analysis of the structures under multiple ground motions with wide frequency domain. The additional position of VE energy dissipation braces should be an important analysis indicators in the optimization design of the structures.

Effect of infill walls on progressive collapse behavior of self-centering precast concrete frame

To study the effect of infill walls on the progressive collapse resisting-performance of self-centering precast concrete (PC) frame structures, three 1/2 scaled, two-span and two-story self-centering PC frame specimens with and without infill walls were tested under quasi-static pushdown loading regime. The test results showed that the failure modes of self-centering PC frames were governed by concrete cracking and local spalling at the beam ends under progressive collapse scenario. Compared with self-centering bare frame, the presence of infill walls provided additional load path, thereby reducing the concrete damage at the beam ends to some extent. The full infill walls with lower strength could still increase the initial stiffness and peak resistance of self-centering bare frame to 2.47 times and 1.33 times, while the infill walls with 20% opening ratio could increase to 2.21 times and 1.19 times, respectively. Nevertheless, the infill walls also reduced the self-centering capacity of the structures. Numerical analyses further indicated that the magnitude of prestress force of steel strands between beams and columns, the strength of bed joints as well as the width of infill walls had a great effect on the progressive collapse of self-centering infilled frames. Finally, based on numerical results, a reduction factor formula was proposed to quickly estimate the structural resistance of self-centering infilled frames with different opening ratios.

Failure mechanism and dynamic response of reinforced concrete joints under impact load acting on beam ends

Beam-column joints are crucial to guarantee the integrity and ductility of reinforced concrete (RC) frame structures. Considering the strain rate effect, the failure mechanism of RC beam-column joints under impact load acting on the beam near the core area of joints was numerically investigated. Based on the verified numerical model, the differences between failure modes of joints under static and dynamic loads were compared. The deformation and damage of joints were analyzed. In addition, the effects of impact location and impact velocity were discussed. The results show that the joints that meet the shear demand under static load have shear failure under impact load. The impact load causes greater deformation and damage to the joints. The transfer of the shear force and the development of the bending moment is different as the impact location changes, resulting in various dynamic responses. As the impact location approaches the core area, the joint evolves from bending failure to shear failure. The maximum shear force only appears at the impact location when the distance between the impact location and the core area is more than 3.5 times the width of the core area (b). However, the rotation of the joint causes the yield of the stirrup in the core area. It is worth noting that when the distance is less than or equal to 2b, the maximum shear force is transmitted to the core area. With the decrease of the distance, the time history curves of impact force have multiple peaks with increased peak values while the displacement and duration decrease. The damage range of the joint is expanded when impacted with higher velocities. Meanwhile, the magnitude and duration of impact force, as well as displacement are increased. With the decrease of distance or impact velocity, more energy is consumed by concrete rather than rebars due to the smaller rotational deformation of the joint.