Moment Resisting Frame Structures Research Articles

Comparative Analysis of the Impact of Vertical Irregularities on Reinforced Concrete Moment-Resisting Frame Structures According to Eurocode 8

Comparative Analysis of the Impact of Vertical Irregularities on Reinforced Concrete Moment-Resisting Frame Structures According to Eurocode 8

Design of E.R. Building At Ct Arsa Palu Hospital With Liquefaction Potential

This design hospital building is planned to be built in the city of Palu. Palu City has high earthquake potential, has history of liquefaction, tsunami and landslides disasters. Thorough design is needed so that this hospital building still become a place for health services after a disaster occurs. The building was designed using the Special Moment Resisting Frame Structure system based on the SNI. Earthquake load analysis uses the response spectrum method based on Earthquake Resistance Planning Procedures (SNI 1726:2019). This concept obtains structure design that meets SNI and still strong in strong earthquake and liquefaction. Analysis has been carried out and it was found that the potential for liquefaction to occur at a depth of 1.5 M to 4.5 M so that the foundation chosen was 4 piles with a diameter of 40 cm, a depth of 6 meters per pile cap. From the results of calculations, it shows that the structure of the emergency room building at CT Arsa Palu Hospital is safe from an analytical perspective.

Seismic collapse fragility analysis of steel moment-resisting frames (MRFs) with stiffness and strength deterioration considering the spectral shape of ground motion records

In this paper, the seismic collapse fragility analysis of special steel moment-resisting frame (MRF) buildings with strength and stiffness deterioration is comprehensively evaluated, taking into account the effect of record selection based on the spectral shape parameters. For this purpose, three special steel moment-resisting frame buildings, including 3, 10, and 20-story structures as representatives of low-rise, mid-rise, and high-rise buildings, are investigated. The modified bilinear Ibarra-Medina-Krawinkler (IMK) relation is used for modeling the concentrated plasticity and considering cyclic degradation in beams and columns under earthquake effects in Incremental Dynamic Analysis (IDA). The ground motion records are selected and categorized based on the three parameters, including the epsilon, SaRatio, and Np from a large database consisting of 2000 earthquake records. The records are divided into 7 groups using the epsilon parameter. The SaRatio and Np parameters further divide the records into 5 categories. Additionally, a randomly selected set of 200 earthquake records is used. The effects of hysteretic deterioration and spectral shape parameters of earthquake records on the median IDA curves, collapse fragility curves, and collapse capacity of the steel MRF structures are investigated. In addition to the hysteretic deterioration of steel structural members based on the results of the previous experiments, different values of the deterioration parameter (λ) are used in the nonlinear time history analyses to parametrically study the effect of deterioration on the collapse capacity. Finally, the effect of various parameters on the seismic collapse capacity of the structures in the form of Tornado diagrams is illustrated. The results demonstrate that the randomly selected records yield results close to the records sets with Np = 1, SaRatio = 1, and ε = 0. Furthermore, for a constant deterioration level, increasing epsilon and SaRatio, and decreasing Np lead to an increase in the collapse capacity of the structures. The results also show that the effect of deterioration on the collapse capacity of the buildings, especially the low-rise 3-story building, is significant.

Innovative approach to estimate structural damage using linear regression and K-nearest neighbors machine learning algorithms

Conventional structural design methodologies often utilize elastic analysis techniques, such as the equivalent static force method and the response spectrum method. While these methods are known for their simplicity and computational efficiency, they prove inadequate in capturing the extent of structural damage caused by seismic forces. Additionally, employing nonlinear dynamic analysis to estimate structural damage represents a challenging and intricate task, posing difficulties for many structural designers. Consequently, the objective of this paper is to present an innovative methodology for evaluating seismic structural damage of moment-resisting frame structures. This involves the utilization of machine learning algorithms, which have been trained and tested on a large data set generated using a newly developed and numerically efficient simulation procedure. The machine learning algorithms employ both linear regression and K-nearest neighbors approaches to accurately replicate the Park-Ang structural damage index.

Seismic behaviour of a steel moment resisting frame structure featuring hourglass double split tee joints

The occurrence of brittle fractures in welds of full-strength joints of steel moment-resisting frames (MRFs) during earthquakes in Northridge (1994) and Kobe (1995) marked a turning point in seismic design philosophies for steel structures. This led to the development of new strategies focusing on enhancing structural resilience and energy dissipation. While Reduced Beam Sections (RBS) were traditionally favoured, recent approaches include partial-strength joints and replaceable dissipative fuses, in some cases also equipped with self-centring components. These systems often employ friction or yielding dampers, ensuring that the weakest joint component comprises well-designed dampers for optimal ductility and energy dissipation.In this context, the present study evaluates the performance of a large-scale structure featuring MRFs with partial-strength double-split tee (DST) joints and hourglass dampers. These joints are conceptually similar to ADAS dampers and the Simpson Strong Tie moment connection prequalified by AISC 358–16. The research involves conducting a pseudo-dynamic test campaign on a two-storey steel structure designed according to EC8 provisions. Findings from experiments and a numerical model developed using OpenSees are discussed. Incremental Dynamic Analyses (IDAs) compare structures with hourglass DST joints to those with full-strength joints, showing enhanced self-centring capacity in DST-equipped structures despite lacking dedicated self-centring components. Additionally, structures with hourglass DST joints demonstrate significant low-cycle fatigue life, potentially reducing the need to replace dissipative components after severe seismic events.

Experimental Study and Seismic Design of Swing Story-Lateral Force Resisting Structural System

A seismic vibration control system, consisting of a swing story substructure, a lateral force resisting substructure and connecting dampers, is recently proposed. The analytical model and optimization method based on the stability maximization and H2 criteria have been established. In this paper, excellent vibration control effects of the proposed system are verified through the small-scale shaking table tests on a two-story model. Experimental results demonstrate the accuracy of the analytical model and the validity of the vibration control strategy. Through numerical analyses of benchmark structures, the input energy of the optimally designed system is remarkably mitigated, and favorable vibration control effects for reducing both inter-story drifts and absolute floor accelerations under earthquake ground motions are verified by comparing with conventional moment-resisting frame structures. In addition, significant control effects can be achieved when the optimal stiffness is greater than the critical buckling stiffness. A seismic design flow chart of the intensity-reduced design method is proposed based on the numerical analyses and the Chinese Seismic Design Code of Buildings. The results indicate that the seismic intensity-reduced design for the proposed system is feasible.

Corrosion effects on the dissipative performance of critical regions of RC frame systems

The influence of degradation phenomena on the dissipative performance of critical regions of reinforced concrete moment-resisting frame structures is investigated through the execution of in-depth numerical analyses reproducing corrosion effects. The model proposed by the Authors in a previous research paper, calibrated using the results of a wide experimental campaign on real-scale substructures, is used for simulating the seismic/cyclic behaviour of plastic hinge regions in correspondence of beam-to-column joints and base-column joints, considering different typologies of reinforcing bars. Corrosion effects were considered in terms of degradation of the mechanical properties of materials (both rebars – longitudinal and transversal, and concrete), confinement deterioration and modification of the bond-stress law as function of the corrosion entity. Results are presented comparing the reference with the different corroded conditions, providing a rational and consistent analysis of corrosion effects in terms of damage, modification of failure modality, material and bond/slip performance.

Seismic behavior and life-cycle cost effectiveness of steel moment resisting frame structures with self-centering friction-viscous dampers

The self-centering friction-viscous damper (SCFVD) is a novel self-centering system that utilizes preloaded ring springs to offer self-centering and friction-based energy dissipation capacity, while a viscous damper provides viscous-based energy dissipation capacity. This study is to study the seismic behavior of steel moment-resisting frames (MRFs) with SCFVDs, considering cost effectiveness. The mechanical model of the SCFVD is first presented and validated through pseudo-static tests on a full-scale specimen. Simulation models of 3-story, 9-story, and 20-story steel MRFs with SCFVDs and viscous dampers are then built, and numerical analysis under 40 earthquake records is conducted on them to compare and evaluate the structural peak dynamic response and energy dissipation from an economic perspective. The results show that the SCFVD's hysteretic response can be reliably predicted by the mechanical model. When compared to the uncontrolled steel-MRFs and the steel-MRFs with FVDs, the SCFVD can significantly mitigate structural peak and residual drift, especially under high-intensity earthquakes, but may aggravate structural peak acceleration. Besides, the SCFVD can mitigate the structural hysteretic energy dissipation and damage to the 3-story and 9-story steel MRFs. The cost/average reduction ratio of peak drift for the steel-MRFs with SCFVDs is reduced by 6.3% when compared to that for the steel-MRFs with FVDs.

Seismic Performance of Ordinary and Damage-tolerant Concrete Beam-column Joints under Reversed Cyclic Loading

The adoption of the capacity design principle in modern codes of practice allows for multi-storey frame structures to exhibit ductile behaviour in a major earthquake without collapsing. Whilst the risk of shear failure in regions of large inelastic deformation can be largely reduced, the detailing requirements in capacity design often leads to reinforcement congestion that adds difficulty during the construction process, due to the high amount of transverse reinforcement required to provide shear resistance and confinement. The work presented in this paper forms a part of a wider research programme that aims to simplify the detailing requirements of transverse reinforcement in the joint and plastic hinge regions of moment-resisting frame structures. To this end, damage-tolerant concrete known as engineered cementitious composite (ECC) was used to substitute concrete in these critical regions. In this article, the results of reversed cyclic tests on two half-scale exterior beam-column joints, constructed with ordinary concrete and ECC, are presented. Key features of the response such as the reversed cyclic hysteresis loops, stiffness degradation and cumulative energy dissipation are discussed, along with crack development under reversed cyclic loading in the form of digital strain maps.

Ideal-Pulse-Based Strong-Motion Duration for Multi-Pulse Near-Fault Records

ABSTRACT Serious damage to near-fault structures is caused mainly by velocity pulses in a ground motion, hence, the necessity to develop a pulse-related definition of strong-motion duration to adequately describe the intensity of near-fault ground motion. For a multipulse record, an ideal-pulse-based strong-motion duration, which is defined as the time interval between the beginning of the first pulse and the end of the last pulse in an ideal-pulse signal, is proposed. This strong-motion duration corresponds with the time interval of the occurrence of strong vibrations and energy accumulations in the original record. For near-fault records, pulselike characteristics can be completely presented within this duration. Meanwhile, the ideal-pulse-based strong-motion duration shows good performance in the estimation of structural responses. The elastic and inelastic displacement spectra of the original records agree well with those of the records shortened according to the proposed duration. The validity of applying the proposed duration to structural analysis is further verified by the nonlinear time history analyses of 3-, 9-, and 20-story steel moment-resisting frame structures. The proposed strong-motion duration accurately estimates nonlinear structural responses. It is proven that the ideal-pulse-based strong-motion duration can adequately describe the intensity of near-fault ground motions, both from the perspective of the energy accumulation process in a ground-motion record and that of the structural analyses subjected to these ground motions.

Experimental validation of a novel curved steel damper for steel frames with flexible beam-column joints

In this study, results of an experimental program are presented to validate the performance of a novel energy dissipation device (EDD) designed for use in moment-resisting steel frame structures with flexible beam-column connections. The EDD, composed of a curved steel plate, stiffeners, and flanges on both ends, was tested in laboratory conditions using a displacement control quasi-static loading protocol. Three half-scale steel frames were used, one serving as a control and the other two incorporating the device in both column-beam joints. The device was fabricated using two different materials, mild steel, and stainless steel, and the results were compared. The results of the experimental program revealed that the frames equipped with the energy dissipation device performed significantly better than the control frame. This was observed qualitatively, in terms of the amount of damage sustained by the frames, and quantitatively, through measurements of the frames' capacity and displacement ductility. Frames that were equipped with dampers showed an approximately 1.5-fold increase in displacement ductility and an 84–113% increase in cumulative energy dissipation compared to the control frame. Overall, this research highlights the potential of this novel energy dissipation device to enhance the seismic performance of moment-resistance steel frame structures.

EVALUATION OF RETROFIT EFFECTIVENESS AND COST IMPLICATIONS OF MRF STRUCTURES USING DISTINCT FRCM COMPOSITE SYSTEMS

This paper summarizes the results of a numerical investigation to assess the effectiveness of retrofitting pre-seismic code concrete framing structural systems using two distinct fiber-reinforced cementitious matrix (FRCM) composites. While FRCM composites were focused in the literature at the member level, this study focuses on implementing this retrofit technique effectively at the structure level. Several static pushover analyses (SPAs) and inelastic dynamic simulations (IDSs) are carried out for FRCM-retrofitted RC frames representing the lateral force-resisting system of a moment-resisting frame (MRF) structure. Correlating the numerical simulation results and experimental results obtained from another study verified the selected fiber discretized section modeling technique for FRCM retrofitted MRFs and reflected the effectiveness of the adopted approach in prolonging local and global damage states. The verified modeling technique of the risk-mitigation measure is then employed to evaluate the performance of an upgraded RC building using three-dimensional fiber-based numerical models. Finally, a parametric study using SPAs and IDSs using multiple seismic scenarios is conducted to select the most effective FRCM retrofit material for the seismic performance enhancement of the benchmark structure. The study concludes that using the selected FRCM retrofit technique effectively mitigated the structural collapse damage state of the substandard building at the design and maximum considered seismic intensity levels by 28% and 32%, respectively.

FE-aided Kalman Filter for nonlinear state estimation with unknown input

A Kalman Filter-Finite Element (KF-FE) framework for joint input-state estimation of nonlinear systems is proposed in the current study. The KF-FE framework has been developed aiming to estimate the nonlinear structural behavior induced by excessive loading such as earthquake-induced ground motions or strong waves, during which a limited number of responses can be measured. The proposed framework involves the use of a Bayesian recursive filter, namely the Kalman Filter, in conjunction with a nonlinear Finite Element (FE) model, which allows to update the state space model formulation at each time step. The proposed KF-FE framework builds its novelty for nonlinear systems on the basis of existing methods for online state estimation of linear systems. The application of such a framework can be suitable for nonlinear state estimation when only output measurements are available. A numerical testbed is adopted herein consisting of a 2D steel moment resisting frame structure subjected to earthquake ground motions. The KF-FE results from the nonlinear numerical analysis scheme indicate estimation performance of high accuracy for both global (e.g., nodal displacements and rotations) and local (moment-curvature relationships) demand parameters while the computational cost is kept low.

Blast reliability assessment and sensitivity analysis of steel MRFs equipped with NiTi SMA bolts

The probabilistic-based assessment of Moment Resisting Frame structure (MRFs) is significantly vital due to the high volatility of blast wave propagation parameters, material strength, and strain rate effect. In this study, the reliability and sensitivity of steel MRFs equipped with Nickel Titanium Shape Memory Alloy (NiTi SMA), and smart MRFs, subjected to Vehicle Borne Improvised Explosive Device (VBIED) are assessed. Since Eurocode does not address the design of a smart structure subjected to blast loading, the smart MRFs are designed based on the Eurocode-complying key design procedures proposed by the author’s previous works. It is always a question if the structure designed based on the proposed Eurocode-complying design methodology satisfies the safety level criteria. The newly developed reliability framework approach by the authors is employed to assess the safety level of the smart MRFs based on the criteria given in the international probabilistic design provisions. Performance functions are parameterized based on three failure modes: axial force and bending moments (global buckling) in the columns, maximum rotation demand at the connections, and system-level structural integrity through Inter-Story Drift Ratio (ISDR). The uncertainties of the charge weight, material strength, gravity loads, model uncertainties, connection behavior parameters, strain rate effects, and column cross-sectional dimensions are considered. The proposed reliability framework is applied to the 4-story, 7-story, 10-story, and 15-story smart MRFs. The results show that the developed smart MRFs satisfy the safety level criteria recommended in the international provisions’ probabilistic design requirement. Furthermore, the reliability-based outcome confirms the efficiency and applicability of the proposed Eurocode complying key design procedures and verifies the deterministic results of the smart MRFs. Finally, the sensitivity of the smart structures to various uncertain parameters is investigated. Among all the parameters, it is found that the Reliability Index (β) of the smart MRFs is more sensitive to the uncertainties of charge weight, column web length(s), connection behavior parameters, and material strength. The sensitivity analysis shows that the smart MRFs are safe under unknown extreme conditions, a very high Coefficient of Variation (COV).

Seismic performance of exterior RC beam-column junction strengthened with Stainless Steel Wire Mesh (SSWM)

Strengthening of concrete structures is necessary to enhance their performance in terms of serviceability and strength requirements as well as to increase the life span of the structure. In the past, different types of fiber-reinforced polymer (FRP) materials are widely employed for strengthening concrete structures. However, FRP-strengthened structural elements exhibit brittle failure as well as debonding of FRP strips or wraps. Due to debonding of FRP, its tensile strength is not fully utilized. To explore an alternative to FRP, Stainless Steel Wire Mesh (SSWM) is chosen in the present study. SSWM is a locally available material having lower tensile strength compared to FRP but having good bond characteristics with concrete and ductile behavior. The present study mainly focuses on experimental investigations to evaluate the behavior of beam-column junction strengthened using SSWM. In this experimental study, the performance of reinforced concrete beam-column junction is evaluated under cyclic loading. The reduced (one-third) scale test specimen representing an external beam-column junction of a 6-story regular moment resisting frame structure was tested under cyclic loading till its ultimate capacity. Subsequently, the damaged beam-column junction was strengthened using SSWM and its performance was again examined under cyclic loading. Minor cracks developed in the specimen were first filled with grout. Subsequently, epoxy-based adhesive SIKADUR 30 LP epoxy was used for bonding SSWM on the surface of the beam-column junction. The performance of test specimen was evaluated in terms of hysteretic response, displacement ductility, energy dissipation, degradation of stiffness, and failure modes of specimens. Results of experimental investigations show that SSWM effectively contributes to load resistance and enhances ultimate load carrying capacity and ductility of the beam-column junction without brittle or any significant debonding from concrete surface. Therefore, SSWM can be an economical alternative of FRP material for strengthening of concrete structures.

Reliability Assessment Methodology of Blast Protective Steel Moment Resisting Frame Using NiTi SMA-based Connection

This paper proposes a methodology framework for the reliability assessment of smart steel Moment Resisting Frame structures (MRFs) equipped with Nickle Titanium Shape Memory Alloy (NiTi SMA) connections subjected to blast loading. The reliability assessment framework is formulated based on a two-step approach algorithm. In the 1st Step, the Monte Carlo Latin Hypercube Sampling Strategy simulation (MC-LHS) is adapted to generate the uncertain parameters sample points. Considering the numerical simulations, the 2nd Step employs simplified performance functions and the generated random outcomes from the 1st Step. The proposed reliability approach is verified against direct Monte Carlo Simulation (MCS) and First-Order Reliability Method (FORM). The performance functions are columns’ axial force and bending moments, rotation capacity at the connections, and Inter-Story Drift Ratio (ISDR). Throughout the development of the reliability assessment, the probabilistic models are parametrized on geometrical properties, material properties, vertical loads, model errors, and charge weights. The developed reliability framework is applied to a prototype 4-story smart MRF. The structural safety level is obtained in terms of the Reliability Index (β). The results show that the reliability framework provides an accurate and efficient structural collapse prediction of the MRFs equipped with NiTi SMA-based connections. Finally, sensitivity analysis is performed to indicate the sensitivity of building collapse to blast wave characteristics, material strength, vertical gravity loads, and column profile dimensions. The sensitivity analysis results also confirm the efficiency of the proposed reliability framework in observing the highly sensitive parameters, which is explosive charge weight.

Shake-table testing and numerical simulation to select the FRCM retrofit solution for flexure/shear deficient RC frames

This paper presents shake-table and numerical investigations to select a retrofit strategy for reinforced concrete (RC) frame structures using fiber-reinforced cementitious matrix (FRCM) composites. Two FRCM alternatives are investigated, namely polyparaphenylene benzobisoxazole (PBO) and carbon FRCM composites, denoted as ‘P-FRCM’ and ‘C-FRCM’, respectively. The study focuses on implementing the selected retrofit material with spike anchorage systems to delay the debonding failure and addresses different failure modes of RC framing systems, including shear or flexure failure. The first phase of this study involves pre shake-table test (STT) simulation to investigate the effectiveness of the selected retrofit technique in delaying local and global damage states and failure modes. STT campaigns are undertaken in the second phase to assess the seismic performance of framing systems retrofitted with different FRCM materials and verify their fiber-based modeling approach. The verified numerical modeling approach of the retrofit techniques is utilized in the third phase to upgrade a benchmark RC moment-resisting frame (MRF) building. A parametric study involving inelastic pushover analyses (IPAs) and multi-record incremental dynamic analyses (IDAs) is finally conducted to assess the vulnerability of the retrofitted building with different FRCM alternatives. It is concluded that the adopted two retrofit techniques significantly reduced the collapse damage state at the design and maximum considered earthquake intensities by up to 59% and 46%, respectively. Although the P-FRCM composite has 38% higher tensile strength and 76% higher ultimate tensile strain than C-FRCM, it slightly improves the overall seismic performance by up to 9% based on the adopted seismic performance index. Owing to the higher cost of P-FRCM compared with its counterpart, a performance-to-cost index confirmed that the C-FRCM composite is the preferred retrofit technique for MRF structures.

Structural behaviour of RC-ECC beam-column connections under quasi-static loading

This research investigates the quasi-static cyclic behaviour of a special moment-resisting frame (SMRF) structure with the application of engineered cementitious composites (ECC) in the beam-column joint. For this purpose, three full-scale beam-column connections were cast and tested under quasi-static loading conditions. The control specimen was cast with the conventional concrete having 21 MPa compressive strength and detailed as per special moment resisting frame (SMRF) requirement. On the contrary, transverse reinforcement was removed from the remaining two (02) specimens with ECC replacing concrete in the joint region and the interface portion of the beam-column connection. Strain gauges and LVDTs were installed at appropriate locations to record the connection's response. After the careful acquisition of data, hysteresis loops, load-displacement envelop and energy dissipation curves were obtained. The test results demonstrated that models with ECC in the joint outperformed the control specimen in ductility, load-carrying capacity and energy dissipation. As compared to the control specimen, the use of ECC in beam-column connection increased the peak displacements by 28.44 %, peak load carrying capacity by 27.13 % and energy dissipation by 58.06 %. Due to high shear strength and ductility, the use of ECC in the joint region was found to address the shear stress requirements without using any transverse reinforcement.

Comparison of seismic fragility of RC moment-resisting frame structures designed according to Chinese and Indian code

Seismic fragility analysis is a method used to evaluate the vulnerability experienced by structures when subjected to earthquakes. In this study, the seismic performance of 18 reinforced concrete moment-resisting frame structures designed according to Chinese code and Indian code is analyzed. A parametric study is conducted by varying the height of the building and the type of soil on which the building is constructed. Nonlinear time history analyses are conducted to develop fragility curves for four different damage levels: fully operational, operational, repairable, and collapse prevention. Linear regression analysis is conducted to correlate the engineering demand parameter (maximum inter-story drift) and the intensity of an earthquake (peak ground acceleration). The results show that the structures designed according to the Indian code experience higher story drift than those designed according to Chinese code, making them more vulnerable to the same earthquake intensity.

Self-Centering Rotational Joints for Seismic Resilient Steel Moment Resisting Frame

A novel self-centering rotational joint (SCRJ) was proposed to replace the plastic hinge at the beam end to achieve a seismic resilient frame without diminishing the structural usability. The quasi-static cyclic tests of the SCRJs with different sets of friction components and disc springs were conducted, with the results showing that the precompressive force, stiffness of the compressive force, and slope angle of the right helicoid surfaces can significantly affect the hysteresis behavior. The hysteresis curve of the SCRJ demonstrates a flag shape with four characteristic states: activation state, ultimate state, reversal activation state, and deactivation state. The displacement-based design approach was adopted for the resilient steel moment resisting frame structure with the SCRJs based on which a six-story resilient frame structure was designed with the SCRJs at the beam ends. The nonlinear dynamic analysis shows that the interstory drift ratio and residual interstory drift ratio of the resilient frame structure can meet the design objectives, in which the SCRJs reach the plastic state (caused by geometric nonlinearity) more easily than conventional plastic hinges (caused by material plasticity), resulting in larger deformations, and can effectively dissipate seismic energy and protect the main frame from yielding under the rarely occurring earthquake (ROE) level.