Beam Frame Research Articles

Dynamic Interaction Analysis of a Coupled System of Permanent Maglev Train and Flexible Track Beam

Vehicle–track beam coupling resonance greatly influences the vibration response of the suspended permanent (SPML) system. Therefore, the study established the coupled dynamic model of the SPML train and the track beam using. The model is used to analyze the dynamic response of SPML trains when passing through the long-span flexible track beam at resonance speed. The accuracy of the model was verified by field tests, which simulated and compared the dynamic responses of maglev train and track beam systems at different running speeds. Furthermore, the coupled vibration response of the train and track beam at resonant speed are investigated to gain insight into the mechanism and vibrational properties of the SPML system in a resonant background. It shows that the dominant frequency of the train, suspension frame, and track beam is 6.74[Formula: see text]Hz. They result in resonance in the SPML system at 30[Formula: see text]km/h. Further analysis shows that adjusting the vertical distance between the mass center of the vehicle and the track beam can effectively alleviate the resonance between the vehicle and the track. Additionally, deformation at the ends of the long-span track beams affects the levitation force and gap of the suspension frame, offering valuable guidance for SPML system design.

Three-dimensional stability of a fill slope reinforced by a frame beam anchor plate

The frame beam anchor plate is a new supporting structure reinforcing fill slopes. At present, only a few studies have evaluated its static stability based on the two-dimensional plane assumption. In this paper, the limit analysis method is combined with the three-dimensional spiral failure mechanism to evaluate the factor of safety (Fs) of a slope supported by a frame beam anchor plate. The pseudo-static approach is used to express the seismic effects. When calculating the internal energy dissipations, both the pull-out failure of anchor plates and tensile failure of tie rods are considered. The accuracy of the approach is verified by comparison with calculation results from the finite element method. Parameter analysis summarizes the influence law of each supporting structure design parameter on the Fs. Therefore, this study develops a theoretical basis for evaluating slope stability reinforced by frame beam anchor plates, which can better guide the design of slopes reinforced by this supporting structure.

Analysis of reinforcement effect of different anchoring forces on slope stabilised by prefabricated anchorage cable frame beams

Prefabricated anchorage cable frame beams represent a new approach to slope reinforcement, displaying distinct deformation and stress patterns under varying anchoring forces compared to traditional cast-in-place frame beams. This renders the traditional theories and engineering practices of cast-in-place beams inapplicable. Field tests and sophisticated finite-difference simulation models were established to examine the mechanical performance of prefabricated beams under different anchoring forces. Initially, field test results validated the simulation models against measured and theoretical data. Subsequently, the impact of different anchoring forces on slope deformation, structural deformation, and stress in frame beams were explored. The beam pressure at the anchoring point of prefabricated beams was 24 % lower than that of cast-in-place beams, exhibiting a linear relationship with increasing anchoring forces and heightened initial sensitivity. Prefabricated beams showed a 20–30 % reduction in anchoring force loss over traditional beams when the anchoring force is not greater than 40 t. Notably, tensile stress emerges in prestressed prefabricated beams when anchoring forces exceed 50 t. The slope deformation with the increasing of anchoring force can be described by a power function. A new deflection deformation index for frame beams was proposed, showing a 70 % reduction compared to cast-in-place beams. During sliding face degradation, deformation differences between adjacent prefabricated beams weaken the reinforcement effect compared to continuous cast-in-place beams. However, applying sufficient anchoring forces significantly mitigates this effect. A well-calibrated anchoring force ensures superior performance of prefabricated anchorage cable frame beams, with enhanced crack resistance, reduced anchoring force loss, minimal deflection deformation. Moreover, the prefabricated beam structure is easy for local replacement and maintenance. This study can make a reference for the application and design of prefabricated structures for slope stabilisation.

Non-contact measurement of structural dynamic displacement based on improved edge detection and video interpolation

In structural health monitoring (SHM), smartphones are increasingly used for non-contact dynamic displacement measurement using computer vision. To overcome limitations in capturing high-frame-rate data, a non-contact measurement method of structural dynamic displacement based on an improved edge detection algorithm and video frame interpolation is proposed. Initially, a smartphone is employed to capture the structure’s vibration video and then generates intermediary frames between adjacent frames that match the structure’s motion state by using a video frame interpolation algorithm to obtain a video with a high frame rate. Subsequently, the improved edge detection algorithm is applied to measure the displacement within the interpolated video. In order to address the problem that traditional edge detection may have false edges leading to the degradation of measurement accuracy, a feature point tracking technique is proposed based on the traditional edge detection technique, which effectively excludes the interference of false edges in ROI and improves the accuracy of displacement monitoring. Experimental validation on a cantilever beam and steel frame bridge demonstrates the method’s viability and precision, highlighting its effectiveness in improving displacement measurement accuracy compared to traditional methods.

Experimental and numerical study on flexural performance of ultra-high performance concrete frame beams reinforced with steel-FRP composite bars

This paper presents the bending tests of four ultra-high performance concrete (UHPC) frame beams and one normal strength concrete (NSC) frame beam, all reinforced with steel-FRP composite bars (SFCBs). A comprehensive analysis was carried out, encompassing evaluation of the failure mode, crack propagation, bearing capacity, deformation, strain response, and plastic rotational capacity of the frame beams. Investigating the effects of concrete type, reinforcement type, and beam-end reinforcement ratio on the flexural performance of the frame beams was a key aspect of this study. A three-dimensional finite element (FE) model of the frame beam was established and rigorously verified. The developed model enabled a detailed parametric analysis involving the steel ratio, the yield strength of the inner core steel bar, the elastic modulus of the FRP, and the ultimate tensile strength of the SFCB. The results indicated a consistent failure mode of all frame beams: crushing of concrete at the beam-end, initiating a sequence of plastic hinge occurrence starting at the beam-end and then progressing to mid-span. The substitution of normal strength concrete with UHPC significantly enhanced various aspects of the frame beams, including the flexural capacity, deformation, ductility, ultimate energy dissipation, and plastic rotational capacity, while inhibiting the generation and expansion of cracks. Notably, the plastic rotation angle of SFCB-UHPC frame beams was 4.9 times greater than those of steel-UHPC frame beams, emphasizing the effectiveness of SFCB in enhancing the beam-end plastic rotational capacity. A decrease in the beam-end reinforcement ratio significantly reduced the flexural capacity, ultimate energy dissipation, and beam-end plastic rotational capacity, while improving ductility. Additionally, the study established a formula for calculating the equivalent plastic hinge length, utilizing the relative compressive zone height and effective section height of the beam-end controlling section as variables, which demonstrated good alignment between predicted and experimental results.

Three-Dimensional Stability of Unsaturated Soil Slopes Strengthened through Frame Beam Anchor Plates under Steady Seepage Conditions

Three-Dimensional Stability of Unsaturated Soil Slopes Strengthened through Frame Beam Anchor Plates under Steady Seepage Conditions

Axial compressive behavior of steel-hollow core partially encased composite spliced columns

Steel-hollow core partially encased composite spliced frame beam (SHSFB) amalgamates the advantages of steel and composite structures, offering excellent deformation capacity, seismic performance, material savings, and reduced weight. These advantages are also essential for frame columns. Therefore, axial compression tests were conducted on four steel-hollow core partially encased composite spliced columns (SHSCs) and one steel comparison specimen to investigate their failure modes and compressive performance. The test results revealed that the SHSC does not fully utilize the compressive performance of the composite part under compression. Based on these experimental results, improvements were made to the configuration of SHSC, and a new type of SHSC (NSHSC) was further introduced. Finite element parameter analysis was conducted on the hollow-core partially encased composite (HPEC) short columns and NSHSCs, respectively, to investigate the confined effect on concrete in the HPEC section and the influence of different parameters on the compressive performance of NSHSC. The simulated results show that the effectively confined area of concrete in the HPEC section increases with thicker H-shaped steel flanges and narrower stirrup spacing. The compressive performance and failure modes of NSHSC are determined by the lower strength of either the steel part or the composite part. Finally, by integrating concrete confined area division and the compressive stability of variable stiffness column, the calculation method for the axial compressive bearing capacity of NSHSC was proposed. The calculated values exhibit good agreement with the simulation results.

Elastic-plastic analysis of a novel prefabricated SRC column-steel beam composite frame structure

The objective of this study is to examine the mechanical behavior of a novel PSRCS (Prefabricated SRC Column-Steel Beam) frame structure under static and dynamic loads. To this end, a PSRCS frame structure with PSRCS joints has been constructed using the OpenSees software, and an elastoplastic analysis has been conducted. The principal findings of the study are as follows: Firstly, a comparison of the test results for the PSRCS joints with the FE (finite element) simulation results demonstrated that the FE model based on OpenSees is an effective means of simulating the load-bearing and deformation performance of the PSRCS joints. Subsequently, a PSRCS frame structure was constructed using OpenSees, and static and dynamic elastoplastic analyses were performed. Compared to the more conventional SRC column-steel beam frame structures, the PSRCS frame structure displays superior deformation capacity when subjected to static pushover action. The PSRCS frame structure exhibits a 'beam hinge' failure mode due to the plastic deformation of the flange connection plates, whereas the failure location of the conventional frame tends to be at the column ends, resulting in a 'column hinge' failure mode. In the context of dynamic analysis, an increase in the number of stories results in an augmented hysteresis of the vertex displacement-time history curve at the upper level of the PSRCS framework. The fundamental natural period T1 of the PSRCS frame is approximately 27.6 % to 34.0 % larger than that of the common frame, contributing to the maintenance of structural stability. In conclusion, a series of design objectives and methodologies based on performance were put forth for the PSRCS frame structure.

Seismic performance of the ST-RC columns to RC beams exterior joint with assembled connection details

An innovative composite column type, the steel tube-reinforced concrete column (ST-RC), consists of a core of concrete-filled steel tube (CFST) and reinforced concrete (RC) encasement. This study aims to validate the reliability of two convenient and rapid assembly methods between RC beams and ST-RC columns. Four full-scale beam-column joint specimens were tested, comprising two prefabricated assembly joints of ST-RC column-RC beam frames, one integrally cast joint of ST-RC column-RC beam frames, and one traditional integrally cast joint of RC column-RC beam frames for comparison. The experiments were conducted based on the principles of a self-balanced system, and quasi-static tests under constant axial compression on the ST-RC columns were performed. Hysteresis curves, skeleton curves, failure modes, strength degradation, energy dissipation capacity, stiffness degradation, deformation capacity and the influence of connection method and joint form on mechanical performance were analyzed and obtained based on the test results. The results indicate that, compared to integral casting, the assembly surrounding method with steel sleeves reduces specimen energy dissipation by 19.8 % and damping ratio by 21 % at 4 % drift, with minimal impact on other mechanical properties. In contrast, reinforcement surrounded and connected by steel plates reduces initial stiffness and peak load-carrying capacity by 1.0 %, along with decreasing negative ductility. It also lowers total energy dissipation by 37.4 % and damping ratio by 45.4 % due to compressive effects from bottom steel plate connections. Despite these effects, its impact on negative ductility and load-carrying capacity remains minimal. Additionally, experimental observations and rebar strain data indicate higher stress on rebars at the base of steel plate connection beams, suggesting a need to strengthen transverse rebars at the beam’s base. The study confirms the feasibility of two convenient and rapid assembly methods for the joints of ST-RC column. Both methods meet current Chinese standards for MCE, with failure modes characterized by “strong columns and weak beams” in both cases.

Deflection Behavior of Reinforced Concrete Beam Frame System with 3/4 Spacing Effective Height of The Beam

Deflection Behavior of Reinforced Concrete Beam Frame System with 3/4 Spacing Effective Height of The Beam

Shear resistance design of prefabricated corrugated steel plate shear walls with reinforced boundary elements

This paper investigates the buckling behavior and shear-bearing capacity of prefabricated corrugated steel plate shear walls (PCSPSWs) with reinforced vertical boundary elements (VBEs). The PCSPSWs are solely connected to the frame beams, and therefore, they can be positioned flexibly within the frame. However, there is currently no available shear-bearing capacity design method for such PCSPSWs. Firstly, this paper conducts a numerical investigation into the elastic buckling behaviors of PCSPSWs using finite element analysis (FEA). The prediction formulas for elastic buckling loads are fitted considering the influence of VBEs’ stiffness on the corrugated steel plates (CSPs). Then, the elastic-plastic buckling performance of PCSPSWs is analyzed numerically. The stability factor (φ) is proposed to predict the shear-bearing capacity of PCSPSWs by introducing the normalized slenderness ratio (λn). Subsequently, this paper explores the effects of PCSPSWs’ position within the frame and the influence of linear stiffness ratios between the frame beams and columns on the shear-bearing capacity of PCSPSWs through numerical analysis. Finally, the lower stiffness values of VBEs are discussed to provide some guidance for structural designers.

Experimental and parametric study on friction-type high-strength bolted connections between steel frames and cross-laminated timber infill walls

Timber-steel hybrid structural systems provide a prospective solution for utilizing timber in multi-storey and high-rise buildings. The system of steel frame with infilled cross-laminated timber (CLT) shear walls is an effective hybrid timber-steel one. In the design of this kind of hybrid system, the connections between CLT walls and steel frame beams are key issues, because they have great impacts on the distribution of lateral forces in structures. In this paper, a friction-type high-strength bolted connection (FHBC) between CLT walls and steel frame beams is proposed. To investigate the performance of the proposed FHBC, experiments were conducted on the FHBCs fabricated with three- and five-ply CLT. The mechanical behaviors of the connections were evaluated. The pretension loss in the tested FHBCs with three-layer CLT is less than 15 % within a displacement of 10 mm. Besides, enhancement of axial force in the high-strength bolt was observed in the five-layer connections during the loading procedure. Theoretical analysis was performed to provide recommendations on the initial pretension force of FHBCs. Furthermore, a solid element-based numerical model was developed and validated by the experimental results. The parametric analysis was conducted to investigate the effect of friction coefficient and initial pretension force on the mechanical behaviors of FHBC. The numerical simulation results show that the greater the initial pretension force is, the bigger the slip activation force and ultimate load-carrying capacity of the FHBC are. When the friction coefficient between CLT wall and steel beam is greater than 0.4, the ultimate load-carrying capacity does not increase much. The experimental and numerical results demonstrate that such connections can provide sufficient stiffness, strength, and ductility to transfer the shear force between the CLT shear walls and the steel frame beams.

Hybrid simulation of steel frames with Dissipative Replaceable Link Frame and high-strength steel coupling beams

The paper describes the results of an experimental campaign conducted on full-scale steel frames equipped with dissipative components within the European Research Fund for Coal and Steel (RFCS) pilot project DISSIPABLE. Dissipative Replaceable Link Frame (DRLF), whose characteristic is the large energy dissipation combined with ease of replacement, were installed on the frame and coupled through high-strength steel (HSS) beams characterised by an elastic response to increase the overall frame stiffness and to improve the re-centring capability after a major seismic event. The seismic performance of the steel frame was investigated by means of Hybrid Simulation (HS) at three different limit states, i.e., damage limitation (DL), significant damage (SD) and near collapse (NC). In particular, the first floor of the frame was physically built, whilst the response of the remaining five floors was numerically simulated. The results of the tests highlighted the large dissipation capabilities of the DRLF system. In addition, the high-strength steel coupling beams remained elastic even at the NC limit state and provided excellent behaviour in increasing stiffness and re-centring capabilities. Finally, the repairability of the DRLF components was demonstrated.

Seismic performance of frame with middle partially encased composite brace and steel-hollow core partially encased composite spliced frame beam

Steel-hollow core partially encased composite spliced frame beam (SHSFB) and middle partially encased composite brace (MPECB) demonstrate the potential to economize on steel consumption while exhibiting superior performance. To investigate the seismic performance of frames with SHSFBs and MPECBs, horizontal low-cyclic loading tests were conducted on four frame specimens, involving two two-story frames with no brace and two multi-story X-braced frames. Numerical simulations were performed using the “Open System for Earthquake Engineering Simulation” (OpenSees). The results indicate that the novel composite frames exhibit commendable seismic performance and energy dissipation capacity. The unbraced frame with SHSFBs has deformation capacity and mechanical properties comparable to bare steel frame. In contrast to the frame specimen equipped with bare steel braces featuring a 6 mm flange thickness, the specimen utilizing MPECBs with 4 mm flange thickness exhibits only a slight reduction of 3.60 % in maximum bearing capacity and 2.68 % in initial lateral stiffness. Significantly, each SHSFB and MPECB component reduces steel consumption by 16.71 % and 24.79 %, respectively, compared to bare steel components. Therefore, while ensuring adequate mechanical properties, frame structures equipped with SHSFBs and MPECBs will require less steel. Based on both experimental and simulation results, the formulas for predicting the ultimate bearing capacity and initial lateral stiffness of the novel composite frame were proposed, and the structural design for the multi-story X-braced frame was analyzed, offering valuable insights for practical engineering applications.

The reliability assessment of the seismic demands of beams in chevron-braced frames and the factors affecting them

According to AISC 341–16, beams in chevron-braced frames should be designed for unbalanced forces. Several factors including the yield strength of steel materials, earthquake magnitude, the number of stories, and the details of the member connections affect the force applied to the beam. In this regard, the present study assessed the reliability of the seismic demand of beams in chevron-braced frames by considering the mentioned effective factors. First, 4-, 8-, and 12-story buildings representing low-, medium-, and high-rise buildings, respectively, were designed based on AISC 341–16. The beam-to-column connections and gusset plates were designed and modeled according to the capacity of the members. Then, one frame was selected from each building for stochastic seismic time-history analysis. For the stochastic analysis, 550 earthquake records were first chosen according to the considered characteristics of the site. Then, 100 ground motions were randomly selected and each braced frame was subjected to them. The yield and ultimate strengths of the steel materials were randomly selected based on the probability density function in each analysis. The results showed that a significant amount of the forces was generated in the beam-to-column connections contrary to the design assumptions. The results in the three frames showed that the resistance of the braced beams was on average higher than the demand forces. Moreover, the force distribution did not show an identical trend in different stories and the effect of the number of stories should also be considered in estimating the unbalanced forces of the braced beams.

Fire performance of steel reinforced concrete column to reinforced concrete beam planar frames: Experiment

This paper investigates the fire performance of large-scale steel reinforced concrete (SRC) column to reinforced concrete (RC) beam planar frames by a series of fire resistance tests. The testing parameters included beam load ratio, column steel ratio and column dimension. The test results indicated that, in fire condition, the SRC column to RC beam frame exhibited two primary failure modes: beam shear failure and column compression failure. In the case of beam shear failure, the fire resistance of frame specimens increased as the beam load decreased. In the scenario of column compression failure, out-of-plane failure occurred due to the weak axis of the SRC column being located outside the frame plane. Concurrently, the RC beam displayed significant shear deformation at the ends and notable bending deformation in the middle. The test results indicated that the column cross-sectional size notably influenced the fire resistance of SRC column to RC beam frame, however, the influence of column steel ratio was minimal.

Seasonal frozen soil area frame beam anchor rod slope support structure frost heave mechanical characteristics simplified calculation model

Seasonal frozen soil area frame beam anchor rod slope support structure frost heave mechanical characteristics simplified calculation model

Geotechnologie stosowane w konstrukcjach antropomorficznych: Wykorzystanie georadaru do wykrywania problemów strukturalnych, przyczyn i skutków - studium przypadku w Coimbrze w Portugalii

One of the recurrent problems in civil construction concerns the wear and deterioration of structures due to their use over time. There should be a plan for monitoring the structures to assess and quantify anomalies, which will allow the minimization and rehabilitation measures to be carried out in advance. This study aimed to use geotechnologies, specifically the Ground Probing Radar (GPR), to identify and quantify the damage caused using a swimming pool inserted in a structure built on a residential property. The methodology comprised the use of georradar Sensors & Software PulseEKKO GPR for data acquisition. The data were processed in the software EKKO Project considering the following parameters: 1- Grain/Filter: Dewow + SEC2 Gain (Attenuation:10.00 Start Gain:4.00 Maximum Gain: 950). Seven acquisition profiles were performed: 3 on the East side, 2 on the South side, and 2 on the West side of the pool, with a spacing between 0.8 m. From the visualization of the processed radargrams, and the slices elaborated for each profile with a color palette corresponding to the obtained reflectance values, it was possible to identify the underlying structures of the pavement of the edge of the pool such as beams, beam frames, slope, interior space of the support structure and, most importantly, the degree of subsoil materials alteration, depth, and dispersion of water infiltrations. On the East side, the pool is inserted into the rock formation; it is possible to identify up to 1 m depth of the water infiltration and dispersion. To the West and South, the pool is supported by a built-up structure; underneath there is a hall and the engine room. In these places, the infiltration and dispersion of water were identified until approximately 0.7 m depth, as well as the existing structures and their condition. The 0.7 m corresponds to the thickness of the existing slab and beams. Based on these results, an intervention plan was prepared for the rehabilitation of the deterioration of the materials and the minimization of water percolation through the waterproofing of the pool's surrounding areas.

Seismic performance of conrete‐filled steel tube column‐reinforced concrete beam frame using 100% recycled coarse aggregate

AbstractThis paper presents an experimental study of recycled concrete‐filled steel tube (CFST) columns with reinforced concrete (RC) beam frames using recycled aggregate under cyclic loading. A 1/3‐scale model of a CFST column‐RC beam frame with 100% recycled coarse aggregate was tested, the failure process and mode were monitored, and the hysteresis and skeleton curves were obtained. The seismic performance indexes were analyzed based on the test data, including the seismic force, plastic hinge sequence, ductility coefficient, inter‐story drift, dissipation capacity, and stiffness degeneration. The general behavior of the CFST column‐RC beam frame is discussed and compared with that of a normal aggregate concrete‐RC frame structure. The test results demonstrate that CFST column‐RC beam frames with 100% recycled coarse aggregate exhibit remarkable seismic performance and can be applied and popularized for construction in aseismic regions.

Performance of RC frames strengthening by external post-tensioning tendons under vertical and lateral loads

In this study, the structural performance of reinforced concrete frames strengthened with external post-tension tendons was investigated. An experimental study was performed to investigate the failure modes and generate the data required to validate the numerical model. The experimental study includes a reinforced concrete (RC) frame control specimen without strengthening and three strengthened specimens under vertical loads. The specimens were strengthened using external post-tensioning with three different tendon layouts, including a straight tendon in the beam-positive moment zone, straight tendons in the beam-positive and column-negative moment zones, and U-shape tendons along the frame beam. The numerical model was built for the four specimens, validated using the experimental results, and used to analyze the lateral load performance. Results showed that the most effective strengthening technique for the vertical load was the beam U-shape tendons, and for the lateral load, it was the beam and column strengthening. It can be concluded from this case study that strengthening frames with external post-tensioning techniques can enhance the first crack load, yielding load, and ultimate load by 80–100 %, 180–250 %, and 35–70 %, respectively.