Pseudo-dynamic Tests Research Articles

Pseudodynamic Tests and Numerical Modelling for Damage Analysis of Infilled RC Frames

ABSTRACT Full-scale experimental tests are still needed to enhance knowledge on the seismic response of existing reinforced concrete buildings and to calibrate numerical models aimed at predicting damage. This study deals with pseudo-dynamic (PSD) tests and numerical modeling of full-scale multi-story infilled RC frames with different infill-to-frame connections. Nonlinear numerical models are calibrated using the experimental results at frame level and validated against the results of time-histories in terms of displacement demand, hysteretic response, and attained damage. This model is extended at building level and used to predicted damage to infills. The comparison with damage observed during post-earthquake inspections is reported and discussed.

Effect of time step interval and time integration schemes in Pseudo-Dynamic analysis

Pseudo Dynamic Analysis technique is an alternative method for exploring structural performance by combining analytical and experimental investigation. Compared to shake table tests, it is a more economical method, and its reliability has been proven over many years of the studies. The damage occurrence and process can be monitored on the test sample due to experiments performed at low speeds. In this study, the behaviour of a single degree of freedom, cantilever column system, under the effect of the pulse load and earthquake record was investigated both numerically and experimentally using Pseudo Dynamic Analysis method. The effects of two different time integration schemes and various time step interval values on analyses were examined in the investigations and the results were compared. Numerical analyses were performed by α-operator splitting method and central differences method, and experimental studies were performed by α-operator splitting method. In experimental investigations, approximate results were obtained with numerical studies for certain values of the time step. At small time interval values, experimental results deteriorated. It is purposed to determine the optimum time step interval value that can be utilised in the Pseudo Dynamic Test method.

Seismic behaviour of steel Moment Resisting Frames with traditional and innovative connections

In the last decades, increasing efforts have been devoted to developing new types of beam-to-column connections able to accommodate the seismic local ductility demand and dissipate the seismic input energy. Among the proposed strategies, the so-called RBS (Reduced Beam Section) has been widely exploited in the construction market. Nevertheless, new proposals based on the partial-strength philosophy gained approval. Their main advantage is that, in the case of rare seismic events, similarly to RBSs, the connections exhibit wide and stable hysteretic cycles, yet concentrating damage in elements that undergo only minor yielding or are easy to replace. The FREE from DAMage (FREEDAM) and the double split (or X-shaped or hourglass) T-stub connections are promising solutions within this framework. The first strategy includes friction dampers in beam-to-column joints to dissipate the seismic input energy and fix the maximum bending moments transferred to the columns. The second solution differs from the traditional one because the flange of the T-element is appropriately cut according to an hourglass shape. This form replicates the bending moment in the plate part between the stem and the bolts, ensuring a uniform yielding of this part.Even though many research works have already been developed on such innovative connection typologies, experimental results on large-scale structures are still quite limited. Aiming to fill this knowledge gap, an experimental program is currently ongoing at the STRuctural ENGineering Test Hall Laboratory (STRENGTH) of the University of Salerno concerning the pseudo-dynamic testing of a large-scale two-storey steel building equipped with the connection typologies mentioned above. The mock-up has experienced the same sequence of five accelerograms in all the campaigns by the pseudo-dynamic test method. This paper discusses the comparison among the main results obtained so far in the experimental campaigns.

Seismic performance of concrete-filled steel tubular composite columns with ultra high performance concrete plates

Two 1:8 scale specimens were designed and created to examine the seismic performance of concrete-filled steel tubular (CFST) composite columns with ultra high performance concrete (UHPC) plates. Ground motion characteristics, axial pressure ratio, plate material, and mainshock-aftershock sequences were used as parameters in the pseudo-dynamic test study. The results show that the ground motion characteristics have a significant effect on the seismic response of the specimen; The initial stiffness of the specimens is mostly unaffected by the axial pressure ratio. Furthermore, the larger the axial pressure ratio, the earlier the specimen enters yielding and the more severe the final failure phenomenon; After UHPC was used in place of the plate material, the specimen's initial stiffness rose by about 13.7%, the stiffness degradation of the specimen was somewhat delayed, and the hysteretic energy dissipation increased by about 41.2%.; The specimen undergoes elastic, elastoplastic, and plastic failure stages under the aftershocks of increasing intensity. Under the mainshock-aftershock sequences of the same intensity, the seismic response of the specimens under the aftershock was not much different compared to the mainshock, and the hysteretic energy dissipation was about 67.7% and 74.5% of the mainshock respectively. These structures can withstand multiple earthquakes and have demonstrated good seismic performance.

Lattice modelling of substandard RC beam-column joints considering localization issues

The strain adjustment for quasi-brittle materials to minimize the mesh size effect and localization issues are investigated by the nonlinear lattice modelling approach for substandard reinforced concrete (RC) beam-column joints (BCJs). The lattice model is generated by implementing the truss analogy for the concrete and reinforcement steel members in RC BCJs. The relevant uniaxial material properties in OpenSees are assigned to the truss members. The reinforcement bond-slip relationship is modelled by zero-length springs attached to steel and concrete elements. The modelling approach is validated by comparing the simulated responses to the experimental behaviour of inadequately detailed RC test specimens. A 3-story 3-bay frame tested with a pseudo-dynamic testing procedure and two substandard RC BCJs tested under quasi-static cyclic loading, one of which contains a slab and an out-of-plane beam, are simulated. To avoid the mesh size effect and localization issues, the strain-based softening function in the uniaxial material property of concrete is adjusted by adopting the crack band approach. Analysis results of the rigid joint model assumption, which does not account for the joint deformation, are also compared with the outcomes of the lattice model. By minimizing the mesh size effect, more realistic results are obtained using the lattice modelling technique with high computational efficiency and less analysis efforts. The model accuracy in reproducing the experimental behaviour and response quantities of prime interest is at a reasonable level for the investigated test specimens.

Evaluation of a coach door under a frontal impact

PurposeThe vehicle´s body front pillar should absorb most of the striker kinetic energy, while only a fraction of that is absorbed by the door structure. This study aims to discuss the aforementioned issue. In this test the striker is a virtual entity. Six uniaxial strain gauges are installed throughout the door. Additionally, contactless 3D digital image correlation (DIC) allows to assess the major door panel’s continuous deformation and strain fields.Design/methodology/approachA coach is a large and heavy long-distance passenger transport vehicle. Their structural certification, classifies coaches as M3 Class III vehicles. New coach structures’ designs need analyses of each sub-system for critical pre-validation of the entire structure, aiming driver and passenger carrier safety. Also, a thorough examination due to increased travel speed is needed.FindingsExperimental pseudo-dynamic (PSD) results were compared and validated using finite element method (FEM) with two pieces of distinct FEM software (Abaqus® and PamCrash®). The time dependent solution was carried out by explicit techniques. Results by FEM and PSD test showed good agreement, evidencing the reliability of the tools selected. Results by PamCrash® were closer to the experimental data.Practical implicationsR-29 is truck-only regulation, however can be adapted to coaches in case of a frontal collision. The present work focuses on the impact behavior of the passenger front door subsystem.Originality/valueAs a first validation the entire structure, the behavior of a vehicle door, under in-plane impacts was studied. The corresponding deformation energy absorbed by the frontal passenger coach door under virtual impacts of a swinging striker was assessed using a PSD approach.

Pseudo-dynamic test and numerical analyses of staggered truss framing systems

To facilitate the popularization and application of high-rise staggered truss framing systems in high intensity area, the seismic performance of the staggered truss framing system was studied. A series of pseudo-dynamic tests were carried out on a 14-story staggered truss framing system model with a scale of 1/8. The time-history curves of displacement, acceleration and base shear under Taft earthquake record with different peak ground accelerations were obtained. Based on the test results, the stiffness degradation, equivalent viscous damping coefficient of the test model were analyzed. The proportion of plastic energy consumption of each component to the whole plastic energy consumption of the structure was obtained. Three different finite element models were established to study the effect of the Vierendeel panel length on the seismic performance. The test results show that the staggered truss framing system has a large lateral stiffness in the direction of the truss, but its seismic energy dissipation capacity is insufficient. Through the pseudo dynamic test method, it is found that the column base is the weak part of the staggered truss framing system. The research results can be used to guide the design of staggered truss framing systems.

Pseudo-Dynamic Test on Composite Frame with Steel-Reinforced Recycled Concrete Columns and Steel Beams

Pseudo-dynamic tests were conducted on a 2/5-scaled, three-story, two-span frame with steel-reinforced recycled concrete (SRRC) columns and steel beams. The El-Centro earthquake waves, Taft earthquake waves, and Lanzhou artificial earthquake waves were considered as the main loads to study the seismic behavior. The failure modes, displacement and acceleration time history curves, hysteretic characteristics, energy dissipation, stiffness degradation, and inter-story drift capacity of the composite frame were analyzed. Results showed that the composite frame did not show plastic deformation during the whole test process, and the steel beams and columns basically did not yield. Under the action of three seismic waves, the displacement response, acceleration response, and restoring force response of the composite frame were increased with seismic intensity, while the hysteretic curves and energy dissipation were different as the seismic wave changed. The seismic response of the composite frame was greatly affected by the spectral characteristics of the loading ground motion and the hysteretic energy mainly consisted of recoverable elastic deformation energy. Under the action of Taft wave with the input peak acceleration of 400 gal (rare earthquake), the stiffness degradation of composite frame was the largest, which reduced to 47% of the initial stiffness. This indicated that the composite frame had good energy dissipation performance in the elastic and elastic-plastic stages, and still possessed good rigidity after a rare earthquake, fully achieving the design purpose of “no collapse in major earthquake”.

Pseudo-dynamic tests on full-scale two storeys RC frames with different infill-to-structure connections

Field surveys showed that the fabrication of infill, with particular emphasis on the connection with the surrounding reinforced concrete (RC) frame, may have a significant influence on the global response, earthquake damage and on the actions transmitted to the surrounding RC members.This study reports and discusses the outcomes of an experimental program on three two-storeys full-scale infilled RC frames varying the concrete strength and infill-to-structure connection. The specimens were subjected to pseudo-dynamic tests at increasing intensity to characterize the frame response and the related damage states. The results showed that the strength and stiffness of the frame increase by increasing the infill-to-structures connection. The enhanced connection allows to have a better loading transfer from the structure to the infill with a strength increase ranging between 10% and 30%. This resulted in a reduction of the displacement demand and in an increase of the shear force transmitted to the top of the column. The results are compared with the damage observed during post-earthquake field survey at building level and with available fragility functions showing a good matching. A non-linear FEM model is proposed to capture the lateral response of the tested frames and the results are compared and discussed. The comparison outlines the reliability of a three-strut model to accurately reproduce the infill response and the shear actions transmitted at the top of the columns.

Substructure hybrid test examining the seismic response of point-supported glass façades attached to large-span spatial steel structures

Point-supported glass façade (PSGF) is one of the most widely used types of non-structural components. Its earthquake damage may not only cause economic loss, but also interruption of building use and even casualties. This paper aims at investigating the seismic response of the large-span spatial structure and PSGF coupling system through the substructure hybrid test. The substructure pseudo-dynamic (PSD) test method is used, that is, the loading rate of the test is slow as that of the quasi-static tests. The finding is that when the glass panel begins to fail, the cracks occur and instantly spread to the whole glass panel along the diagonal direction due to the stress concentration at a bolt hole of double-layer laminated glass, accompanied by looseness of several point-fixed fitting screws. The drift angle of one glass panel is about 50.0%–81.9% of that of glass façade δ in the critical and failure state, indicating that the supporting system can reduce the in-plane deformation of the glass panel. And the glass façade can reduce the acceleration responses of the mid-span upper chord nodes of the large-span spatial structure by 4.74%–13.98%. Finally, the seismic performance evaluation indexes of PSGF are determined based on the drift angle δ and percentage of damaged glass panels for the slight, moderate, and extensive limit states. It will provide an example and reference for the seismic performance evaluation of the PSGF.

Progressive collapse analysis of RC frame building based on Pseudo-Dynamic (PsD) testing with sub-structuring

Accidental loading coming from either natural or anthropic hazards can have serious consequences on civil engineering structures capacity and can lead to progressive collapse (PC). In the case of frame buildings, PC is a subject of interest to assess the residual risk of exposure to death for people inside. PC analysis on large structures is rather performed from a numerical point of view. Experimental tests are often expensive and complicate to setup (dynamic response, removal of the load-bearing element, size of the experiment, etc.). In this paper, the use of Pseudo-Dynamic (PsD) testing combined with sub-structuring technique is proposed. It allows to account for the dynamic response of the entire structure by only testing (quasi-statically) the critical part of the building. In order to demonstrate the applicability of the method to PC, a classic central column removal scenario is considered and applied on a Reinforced Concrete (RC) structure. The latter is a two-bay and three story frame building. The bending response of the RC beam directly connected to the removed load-bearing member is investigated. Only this part (the RC beam) is experimentally tested while the rest of the structure is simulated by finite element analysis within a dynamic framework. The quasi-static response of the beam is measured and interacts with the integration scheme (α Operator Splitting type) to calculate, inter alias, the inertial forces contributions and the displacement fields within both numerical and experimental domains. To validate the approach, a finite element model based on multifiber beam theory is used. The results comparison underlines a very good agreement between both PsD tests and numerical simulations in all configurations considered, in particular the ability of the PsD approach to account for inertial effects within the structural response. It demonstrates the interest to use such a method within the context of PC analysis. More specifically, the method could prove particularly effective to assess Dynamic Amplification Factors (DAF), used for structural design by accounting for PC potential effect (at least within American guidelines).

Multifiber finite element model based on enhanced concrete constitutive law to account for the effects of early age damage on the seismic response of RC structures

RC structures get damaged over time due to several phenomenons such as shrinkage, thermal deformations, creep and corrosion. This damage starts at early age and continues during the lifetime of the structures. In order to account for the effects of early age damage on the seismic response of RC structures, a research project combining both an experimental and numerical part was conducted. In the experimental part, two types of portal frames that evolved either in endogenous conditions (by covering them using a plastic sheet to limit drying shrinkage) or in non-endogenous conditions (no imposed covering, thus similar conditions as in site constructions) during early age, were constructed and tested at the end of 28 days using static cyclic and pseudo-dynamic tests. Experimental tests performed and monitoring techniques used (ambient vibration, digital image correlation, optical fiber) showed that early age drying shrinkage can cause an increase of the seismic vulnerability of RC structures (50% decrease of the fundamental frequency, 33% lateral drift increase). This article presents the multifiber finite element model based on enhanced constitutive law which allows describing the early age damage due to shrinkage, creep, thermal and mechanical strains and to simulate the static and dynamic response of the portal frames. The resolution of a THC (Thermo-Hygro-Chemical) problem allows calculating shrinkage and temperature time evolutions. In the model, creep is calculated using three viscoelastic Kelvin Voigt models in series with the μ damage law for concrete (through the resolution of an internal equilibrium at the fiber level) whereas steel is accounted for using a Menegotto model. Results obtained using the numerical model were compared to experimental ones in order to validate the proposed model.

Seismic Strengthening of R/C Buildings Retrofitted by New Window-Type System Using Non-Buckling Slit Dampers Examined via Pseudo-Dynamic Testing and Nonlinear Dynamic Analysis

In the present study, a window-type seismic control system (WSCS) using non-buckling slit dampers (NBSDs) was proposed and developed to address the disadvantages of conventional seismic control systems so that it can be effectively applied to existing reinforced concrete (RC) buildings. Materials testing was also conducted to examine the material performance and energy dissipation capacity of NBSD. A full-scale two-story test frame modeled from existing RC buildings with non-seismic details was subjected to pseudo-dynamic testing. As a result, the effect of NBSD-WSCS, when applied to existing RC frames, was examined and verified, especially as to its seismic retrofitting performance. In addition, based on material testing and pseudo-dynamic test results, a restoring force characteristics model was proposed to implement the nonlinear dynamic analysis of a test building retrofitted with NBSD-WSCS. Based on the proposed restoring force characteristics, nonlinear dynamic analysis was conducted, and the results were compared with those obtained by the pseudo-dynamic tests. Finally, in an attempt to commercialize this NBSD-based WSCS, nonlinear dynamic analysis was conducted on the entire RC building with non-seismic details retrofitted with NBSD-WSCS. The results showed that the RC frame (building) with no reinforcement applied underwent shear failure at seismic intensity of 200 cm/s2, a typical threshold applied in seismic design in Korea. In contrast, in the frame (building) retrofitted with NBSD-WSCS, only minor earthquake damage was expected, and even when the seismic intensity was set to 300 cm/s2, the maximum intensity that had been observed in Korea, only small or moderate seismic damage was expected. These results confirmed the effectiveness of the seismic retrofitting method using NBSD-WSCS developed in the present study.

Ethernet-Based Servo-Hydraulic Real-Time Controller and DAQ at ELSA for Large Scale Experiments

ABSTRACT This paper presents an overview of the developments performed at the European Laboratory for Structural Assessment (ELSA) of the Joint Research Centre of European Commission concerning the new generation of servo-hydraulic real-time digital controller/acquisition system adopted in large scale experiments. The hardware architecture is based on EtherCAT® modules that guarantee a versatile and modular system easily adaptable to changing requirements (a typical situation experienced at ELSA with custom adapted non-standardized large scale structural experiments). Other fundamental features of this system are that all the analog signals are digitalized in the proximity of the transducers reducing noise-to-signal ratio (a great advantage for Pseudo-dynamic tests but in general for all experimentation), and all the different slave controllers communicate at each time sampling through a deterministic robust digital bus. In addition to the increasing computer performances, the developed simplified software architecture does offer a substantial improvement of control quality in terms of speed, safety, and accuracy compared with conventional/commercial systems.

Experimental response of a large-scale two-storey steel building equipped with low-yielding friction joints

The recent earthquakes have underlined the need for more advanced design philosophies able to avoid or reduce direct and indirect costs related to the occurrence of destructive seismic events. According to the traditional seismic design approach, under rare and very rare seismic events, the onset of damage to structural components is usually accepted. However, to address social expectations and the need for resilient buildings, recently, novel low-damage design philosophies have been proposed. These are based on the introduction of friction devices able to dissipate large amounts of energy with negligible damage. The cost of repair of these devices is typically only related to the re-tightening of bolts and, eventually, the substitution of friction shims. Noteworthy examples of this technology are the Sliding Hinge Joints (SHJs), developed at the University of Auckland, and the FREEDAM joints, developed at the University of Salerno within the framework of a homonym research project.In the last two decades, significant efforts have been devoted to understanding the seismic behaviour of such connections. The novelty of this work consists in investigating, for the first time, the seismic response of a large-scale building mock-up equipped with FREEDAM joints. The mock-up has been tested with a sequence of five accelerograms using the pseudo-dynamic testing method. The results have confirmed that FREEDAM connections provide large energy dissipation and rotation supply with almost no damage. The experimental results have been used to verify the accuracy of a numerical model developed with the software OpenSees, showing the capabilities of current simplified phenomenological modelling approaches in capturing the actual structural response.

Seismic tests and nonlinear model of beam-CFDST column joints with blind fasteners

In recent years, substantial research efforts have turned towards concrete filled double skin steel tubular (CFDST) column due to its superior mechanical performance. However, an effective and convenient connection method between a CFDST column and a beam still needs to be investigated in depth. This paper tried to adopt the blind bolting technology in a CFDST column to beam connection. A series of joint specimens were prefabricated and designed with different end plate types, column hollow ratios and beam types to carry out pseudo-dynamic tests. Excellent seismic performance was detected for all test specimens. It was observed that increasing the column hollow ratio could moderately increase the ultimate strength and the specimen with extended end plate had higher ultimate strength stiffness compared with that with flush end plate. To accurately capture the dynamic response for this type of joint, an analytical model was developed considering the shear performance of panel zone and moment-rotation behavior of connection. Shear strength of CFDST column panel zone was modified from that of CFST column panel zone based on the yield line method for including the contribution of confined compression strut. It indicated that two potential yield mechanism might appear depending on the column hollow ration (χ). The analytical model could well predict the test results. The research and analytical results provided an effective connection method to assemble a CFDST column to a beam and supply a feasible analytical model to predict the joint performance.

Effects of cyclic strain hardening on performance of eccentrically braced frames

Performance based seismic design (PBSD) procedures have been developed in recent years. Studies conducted in the past revealed that strain hardening ratio (SHR) used in numerical modeling can be influential on the performance of steel structural systems. In this paper, the effects of SHR on the performance assessment of eccentrically braced frame (EBF) buildings were studied by using FEMA P-58 methodology. The numerical model was validated using the pseudo-dynamic test results of the DUAREM structure. Seismic performance of six archetype EBFs with different number of stories and link length to bay width (e/L) ratios were evaluated under design basis earthquake (DBE), maximum considered earthquake (MCE), and collapse level earthquake (CLE). Irreparable residual drift, repair cost and unsafe placards were calculated for SHR ranging between 0 and 0.01. The results showed that the residual interstory drift ratio is more influenced by the SHR when compared with the interstory drift ratio, link rotation angle and story acceleration. The replacement decision was found to depend on the SHR, the number of stories, the e/L ratio, and the seismic hazard. Under MCE and CLE level events, almost all of the archetypes with SHR ≤ 0.003 required replacement while replacement can be avoided for some of the archetypes with SHR > 0.003. Under DBE level events, 3-story archetypes and 6-story archetypes with SHR ≥ 0.002 did not require replacement. Nine-story archetype with e/L = 0.08 required replacement for SHR = 0 only, while archetypes with e/L = 0.12 required replacement for SHR ≤ 0.003. The study demonstrated the strong influence and sensitivity of the repair cost to the SHR.

Substructure Modeling and Loading-Control Techniques for the Test of a Full-Scale Spatial RC Frame with Buckling-Restrained Braces Subjected to Bidirectional Loading

To investigate the performance of reinforced-concrete frames with buckling restrained braces (RCF-BRB) subjected to bidirectional earthquakes, a full-scale two-story RCF-BRB was tested using substructured pseudodynamic (PsD), quasistatic, and pushover techniques. This paper focuses on the structural modeling for the substructured PsD tests, and the control and measurement issues of the bidirectional loading system. To make a credible reproduction of the structural response using substructured PsD technique, an overlap modeling technique together with tuning the mass of the lamped-mass model and stiffness of the numerical substructure was employed to reduce errors caused by the incomplete boundary condition. The outer-loop control method based on Newton’s iteration method was introduced for the loading system, with the data from external displacement sensors as the feedback to avoid errors caused by possible gaps in the connection parts of the loading system. The redundancy issue, caused by the actuators outnumbering the degrees of freedom of the floor to be controlled, is addressed with a force-displacement mixed control technique. The three of four actuators were controlled in displacement mode, whereas the redundant one was in force mode. The force command to the redundant actuator was determined with the optimization criteria to minimize the loads relative to the capacities of the actuators. The working range of the displacement sensors is investigated using numerical and geometric approaches. Failure examples from numerical simulation and experiment were shown to emphasize the importance of proper arrangement of displacement sensors. A rearrangement of the displacement sensors was proposed for the pushover test to enlarge the working range. Time-history results of the prototype structure using the calibrated finite-element model show that the PsD substructure test results could represent seismic responses of the prototype structure. The measured mass-center displacements accurately tracked the target displacements throughout the test, indicating the effectiveness of the loading control and measuring system.

Study of effect of shear wall in the seismic response of the existing buildings

In Iraq, it has been observed that an increase in seismic activity, and that most existing buildings are not seismically designed and that can suffer serious damage or collapse, thus causing loss of life. In this paper, a numerical simulation of the experimental laboratory sample on the subject of non-seismically designed buildings and methods of strengthening them was performed using a seismic strengthening technique using an infill RC wall in order to maintain the risk of earthquakes. This study was carried out through the work of verifying the numerical and practical model by matching the results of laboratory work with the results of numerical analysis using the analysis finite element analysis method (FEAM) by Abaqus CAE 2019 software and then using the model to study the effect of openings in the infill RC walls and the extent of its impact on the response of the building. The practical model is a full four-story building tested laboratory in Elsa, Italy using pseudo dynamic test (PSD). The experimental model is a sample of not seismically design buildings (gravity design only) and ways to improve them by adding new RC walls with different contact details to the existing building. The goal of the experimental test was to study the effectiveness of adding RC infill walls with two types (North and South) infill RC walls, including designing it and the contribution of two types of dowels that connect the new infill walls to the existing RC building. In other words, it’s a way of strengthening by converting selected bays into RC walls with two types of reinforcement and connection between new infill RC walls and existing builders called (north and south) frames. The results of analytical modeling show that the percentage of differences in X- Direction of top story displacement between Abaqus software and Experimental tested at ELSA results are 2.47% in positive and 3.12% for negative X direction, which refer to a very good similarity and accurate building simulation.

Assessment of existing steel frames: Numerical study, pseudo-dynamic testing and influence of masonry infills

Most of existing steel multi-storey frames in Europe have been designed before the introduction of modern seismic design provisions, hence they often exhibit low performance under earthquake loads due to their low lateral resistance and energy dissipation capacity. In addition, such structures often include rigid and brittle masonry infill walls that highly influence their lateral response and distribution of damage pattern. However, current procedures for the assessment of existing steel buildings in Europe, included in the Eurocode 8 – Part 3 (EC8–3), do not provide adequate guidance for the assessment of ‘weak’ steel frame with masonry infill walls. Moreover, most of available modelling approaches of masonry infills formerly developed for reinforced concrete (RC) structures do not properly represent the behaviour of infill walls in steel frames. An improved numerical has to be provided to satisfactorily mimic infill walls' behaviour in steel moment frames. To this end, an experimental and theoretical study was carried out within the framework of HITFRAMES (i.e., HybrId Testing of an Existing Steel Frame with Infills under Multiple EarthquakeS) SERA project. This paper firstly presents the limitations of current EC8–3 by conducting a code-based assessment on a case study steel moment frame using pushover analysis. Three different single strut models, widely used for simulating the presence of masonry infills in RC structures, are considered for the numerical analyses. The paper also presents the results of pseudo-dynamic (PsD) tests performed on a large-scale 3D steel frame with masonry infills. The capability of the different masonry infill models is successively evaluated by comparisons between numerical and experimental results. On the basis of the obtained results, recommendations on how to potentially improve the single strut model for masonry infills surrounded by steel frames are also provided.