Frame Structure Research Articles

Shear Force of Interior Beam–Column Joints under Symmetrical Loading with Two Transverse Forces on the Beam †

The beam-to-column connection is a particularly vulnerable element in frame structures under seismic action and is often responsible for building damages. Experimental investigations carried out over the past six decades on shear strength in frame joints have not led to the establishment of a uniform procedure in the design codes of different countries. The reason lies probably in the varied nature of the investigated parameters and in the varied configurations of beam–column connections. A good knowledge of the forces passing through the frame joints in the beam–beam and column–column direction would allow both their adequate computation in new buildings and the verification of existing ones without requiring experimental studies. In the design codes of the leading countries in seismic engineering, the shear force is determined by the capacitive method, considering only the area of the longitudinal reinforcement of the beam passing through the column. This method shows us how much shear force the beam reinforcement can take, but not what the magnitude of the resulting forces actually is as a result of the acting loads. In addition, the method of the codes does not indicate the contribution of the concrete to the total magnitude of the shear force in the beam–column connection. In the proposed mathematical model for calculating the forces that leave the beam, the full dimensions of the cross-section of the beam were taken into account. The material properties and cross-sectional shape were also taken into account. A determining factor for the magnitude of forces entering the beam–column joint is the acting load on the beam. In this paper, the load of two transverse forces was considered. The forces are applied in different possible positions, while remaining symmetrically located on the beam. The calculations are based on Menabrea’s theorem to determine the hyperstatic unknowns. The results of the proposed method for the considered beam show that the magnitude of the shear force differs from that accepted in the literature and the norms by 2% to 27%, depending on the stage of development of the crack. In comparison, the Eurocode-recommended method shows differences in the order of 27% to 40% for the adopted beam under static loads.

Design and demonstration of a roll-out membrane antenna based on thin-walled deployable composite booms

The thin-walled deployable composite boom (DCB) features the advantages of high deployment-to-package envelope ratio and elastic self-development, which is an enduring topic of interest in the field of lightweight aerospace structures. The structural design and performance demonstration was proposed herein for a roll-out membrane antenna (ROMA) based on DCBs. Firstly, a simplified analytical algorithm was formulated for approximate fundamental frequencies of the ROMA frame structure, and the two types of first-order torsional modal shapes of the frame structure was investigated with respect to configurational design parameters. In sequentially, the bending, swing and the two distinct torsional fundamental frequencies of the ROMA frame were estimated comparatively. Furthermore, the effects of the equilibrated tension from the membrane array on the bending fundamental frequency of the ROMA structure was investigated by assuming a simplified mass distribution model for the thin-film structures. Finally, The simplified analytical algorithm was used for structural design of an AIS/VDE (automatic identification system/VHF data exchange system) ROMA and its performance was validated through numerical simulations and ground tests. The successful deployment and operation of the AIS/VDE ROMA on the Pujiang-2 satellite further demonstrated the practical aerospace application significance of thin-walled DCBs.

Research on column overdesign factor of reinforced concrete frame structures in the 2022 Ms 6.8 Luding earthquake

The strong column-weak beam failure mode of reinforced concrete (RC) frame structures is one of the most important targets of structural seismic design and is primarily realized by a reasonable column overdesign factor (COF). However, most RC frame structures in previous earthquakes were often subjected to strong beam-weak column failure modes. To address this issue, the RC frame with a strong column-weak beam failure mode and a typical strong beam-weak column RC frame in the 2022 Ms 6.8 Luding earthquake were intensively studied in this study. The differences between the two failure modes of the RC frame structure were comparatively analyzed at both the overall structure and member levels. A numerical simulation was conducted to obtain the structural response under actual ground motion. Finally, a probabilistic analysis method was adopted to process the COF data of the RC frame joints. The results indicate that the structural safety redundancy of the RC frame with the undesired failure mode cannot be fully utilized, whereas the RC frame with the strong column-weak beam failure mode allows more structural members to participate in the energy dissipation through a complex redistribution mechanism of internal forces. Damage to the infill wall further mitigates the degree of damage to the main structure and reduces the risk of soft-story failure. The COF of the actual RC frame structure shows a non-uniform distribution, and it is recommended that the COF be higher than 1.5 for the seismic design of the structure following the Chinese code.

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

Comparative analysis of seismic response and vulnerability of laminated bamboo frame structure under near-field and far-field earthquake actions

The study offers an evaluation of seismic response and vulnerability for a five-story laminated bamboo frame structure, assessing the effectiveness of seismic intensity measures across various damage thresholds and the modeling uncertainties involved. A structural finite element model was developed in OpenSees software, utilizing the Pinching4 model to accurately represent the non-linear characteristics of T-shaped steel connections in beam-column joints. Two collections of earthquake records, one consisting of pulse-like near-field and the other of far-field events, were utilized to examine the structure's nonlinear behavior. Additionally, vulnerability curves for various damage states were generated using the multiple stripe analysis technique, applied to both ground motion datasets. The applicability of 24 seismic intensity measures was also analyzed across various damage limit states. The modeling uncertainty under different seismic actions was further estimated using a first-order second-moment method. Ultimately, the annual collapse probability of the structure are elucidated. Research indicates that due to the influence of joint stiffness, the overall structure demonstrates dynamic characteristics that are predominantly of the first mode shape. The spectral acceleration associated with the fundamental period achieves a reduced logarithmic standard deviation in the vulnerability analysis across various limit states. Other IMs considering higher mode effects or softening period actions no longer predominate. In most cases, the modeling uncertainty under far-field seismic action is higher than that under near-field, especially at the severe damage limit states by using an efficient intensity measure. The laminated bamboo frame structure faces a much higher collapse risk in near-field than in far-field conditions.

RESEARCH OF THE METHODS OF STRENGTHENING REINFORCED CONCRETE COLUMNS DURING THE RECONSTRUCTION OF INDUSTRIAL BUILDINGS

Over the past two years, Ukraine has noted significant losses of the state's residential and non-residential stock as destroyed or partially damaged. Damaged or destroyed buildings must be restored, reconstructed and dismantled and new ones erected in their place.Industrial facilities suffered significant destruction. In addition, the condition of the structures of many old enterprises is extremely unsatisfactory.Currently, only in Kyiv, about 30% of the city's territory is industrial territory.Depending on the level of reconstruction of the object, it is possible to perform certain structural and enclosing elements. Any intervention in the structural elements of buildings must be preceded by an examination of both the building as a whole and these structures themselves.Repair, dismantling or strengthening of frame structures are among the typical types of work during the reconstruction of industrial facilities. The vast majority of old industrial buildings in our country have a reinforced concrete frame, especially the buildings that were erected in the 60s of the 20th century and in later periods. These are those buildings whose structural condition still allows for reconstruction or repair in order to continue their intended use. Buildings of an earlier stage, as a rule, are subject to reconstruction (if they are monuments of culture and architecture) or dismantling.The article investigates various methods of reinforcing reinforced concrete columns, which are key structural elements of industrial buildings, during their reconstruction. The technological and organic features of reinforcement are presented. The destabilizing factors that affect the efficiency of work are systematized. Modern technologies are studied, including changing the structural scheme, increasing the cross section, injecting into the body of the structure and external gluing of metal reinforcing structures.The effectiveness of each method is analyzed, which allows to assess their advantages and disadvantages, costs and duration of the reconstruction process. In particular, attention is focused on methods that increase the bearing capacity and durability of structures without significant interference with the overall structural scheme of the building.The results of the study allow us to identify optimal solutions for different types of industrial buildings, which helps engineers and designers ensure the sustainability and safety of reconstructed facilities.

A spectral element approach for response spectrum estimation of frame structures with uncertain parameters subjected to stationary stochastic excitations

Determination of the response spectra of structures under excitation is crucial for vibration control, reliability analysis, fatigue life prediction, and optimization design of structures. However, available methods can be time-consuming and even erroneous when dealing with structural uncertainty, making them difficult to apply to actual complex structures. This paper proposes a spectral element approach for response spectrum estimation of structures with uncertain parameters subjected to stationary stochastic excitations. First, the spectral element method and Karhunen-Loève expansion technology are utilized to represent the response spectra of structures with uncertain parameters to reduce computation cost. Then, a dimension-reduction technology of random variables is utilized to simplify the numerical computations while retaining accuracy. Based on the above, the method for the envelope response spectrum with practical applicability is proposed in this study. The method can accurately and efficiently estimate the response spectrum of structures with uncertain parameters. The proposed approach is validated by comparison with the Monte Carlo method using three numerical examples.

H∞ optimum design and nonlinear seismic performance assessment of tuned-mass-damper-inerter (TMDI) supported by an auxiliary structure

Tuned Mass Damper Inerter (TMDI) and its simplified form, Tuned Inerter Damper (TID), are highly effective in mitigating seismic responses in buildings, particularly when rigidly connected to the ground. However, practical constraints often limit the feasibility of this ideal setup. This study introduces a novel configuration: the AS-type TMDI, which connects the TMDI to an auxiliary structure (AS) adjacent to the main building to simulate a ground connection. To design the AS-type TMDI, this research builds upon insights from studies on TMDIs in adjacent buildings and develops an analogous 3-DOF model representing the TMDI-linked adjacent-building system. This model incorporates two buildings of different heights, allowing the TMDI to be connected at any floor level. Utilizing fixed-point theory, the study derives an analytical solution for the optimal design of TMDI systems within this novel configuration. Additionally, a method is introduced to determine the optimal stiffness and design procedure for the AS itself. The performance of the proposed AS-type TMDI is evaluated through comprehensive nonlinear seismic analysis of a benchmark nine-story steel frame structure, accounting for material and geometric nonlinearities. Results demonstrate that the AS-type TMDI performs comparably to a virtually grounded TMDI in effectively reducing the seismic responses. Furthermore, this innovative configuration outperforms both a conventional retrofitting technique, where the building is rigidly connected to the AS, and a system where a viscous damper alone connects the main building to the AS. This highlights the AS-type TMDI's potential to significantly improve the building’s seismic performance.

The cryptic complex rearrangements involving the DMD gene: etiologic clues about phenotypical differences revealed by optical genome mapping

BackgroundDeletion or duplication in the DMD gene is one of the most common causes of Duchenne and Becker muscular dystrophy (DMD/BMD). However, the pathogenicity of complex rearrangements involving DMD, especially segmental duplications with unknown breakpoints, is not well understood. This study aimed to evaluate the structure, pattern, and potential impact of rearrangements involving DMD duplication.MethodsTwo families with DMD segmental duplications exhibiting phenotypical differences were recruited. Optical genome mapping (OGM) was used to explore the cryptic pattern of the rearrangements. Breakpoints were validated using long-range polymerase chain reaction combined with next-generation sequencing and Sanger sequencing.ResultsA multi-copy duplication involving exons 64–79 of DMD was identified in Family A without obvious clinical symptoms. Family B exhibited typical DMD neuromuscular manifestations and presented a duplication involving exons 10–13 of DMD. The rearrangement in Family A involved complex in-cis tandem repeats shown by OGM but retained a complete copy (reading frame) of DMD inferred from breakpoint validation. A reversed insertion with a segmental repeat was identified in Family B by OGM, which was predicted to disrupt the normal structure and reading frame of DMD after confirming the breakpoints.ConclusionsValidating breakpoint and rearrangement pattern is crucial for the functional annotation and pathogenic classification of genomic structural variations. OGM provides valuable insights into etiological analysis of DMD/BMD and enhances our understanding for cryptic effects of complex rearrangements.

A novel optimal design method for tuned mass dampers with elastic motion‐limiting stoppers

AbstractTuned Mass Dampers (TMDs) are commonly used passive control devices in practical engineering applications. However, motion‐limiting stoppers are usually installed to control the excessive TMD displacement due to the building space limitation, resulting in piecewise nonlinearity and detuning of TMD. This paper studies the influence of elastic motion‐limiting stoppers on the optimal design of TMDs through a piecewise stiffness TMD (PSTMD) model. Performance of a PSTMD with classical design is first investigated and proven to be ineffective. To optimize the PSTMD parameters, the motion of PSTMD is decoupled from the controlled structure, and the frequency response equation of PSTMD is obtained analytically through the averaging method. Subsequently, the solution of the optimal design frequency for PSTMD is transformed into the solution of the jump frequency in the frequency response equation. With the optimal frequency of PSTMDs, the optimal damping and control performance of PSTMDs are discussed and analyzed compared with classical linear design, which fully showcases the effectiveness of the novel design method. Finally, the effectiveness of the novel design method is verified using a nine‐story benchmark frame structure, and the results demonstrate that the control performance of the optimal PSTMD can be improved by nearly under specific seismic excitation, compared to the PSTMD with classical linear method. In summary, the novel design method can effectively take into account the influence of piecewise nonlinearity caused by elastic motion‐limiting stoppers and improve the optimal control performance of TMD in a more realistic engineering environment.

Cognitive foundations of the formation of communicative competencies in the theory of dialogue

Abstract The study of cognitive mechanisms involved in the process of developing communicative competencies, particularly from the perspective of dialogue theory, is relevant and necessary to improve communicative activity and its effectiveness. The purpose of this research is to study the cognitive-communicative interaction in the process of dialogical communication and the cognitive conditionality of the development of communicative competencies. The methods of frame, cognitive and communicative analysis, and the analytical-synthetic method were used in the study. The main frame structures of dialogic speech were considered: using one frame and similar ways of verbalization, using one frame and different ways of verbal expression, and using two frames with different thematic or semantic content. The study examined cognitive-communicative interaction in dialogic communication and the cognitive basis for developing communicative competencies. Among the important conclusions is the discovery of three primary dialogical unity frame structures. It has been found that cognitive functions affect successful communication. The study demonstrated how cognitive-communicative interaction fosters the development of communicative competencies. It was also determined that dialogue structure relates to response shifts represented as interrelated frames. The study concludes that future research should focus on studying cognitions in communicative contexts and improving foreign language communication.

Deep Learning Method for Post-earthquake Damage Assessment of Frame Structures Based on Time–Frequency Analysis and CGAN

Deep Learning Method for Post-earthquake Damage Assessment of Frame Structures Based on Time–Frequency Analysis and CGAN

Layout Optimisation of Frame Structures with Multiple Constraints and Geometric Complexity Control

Layout Optimisation of Frame Structures with Multiple Constraints and Geometric Complexity Control

Improved PBPD method for dual steel system considering the global effect of space frames

Performance-based plastic design (PBPD) method has been proposed to design single bay planar frames for twenty years. For a dual steel system, such as an eccentrically braced frame (EBF) structure, there will be both EBF bays and moment resisting frame (MRF) bays. So, the global effect between different frame bays cannot be considered when designing the global structure using the traditional PBPD method. In this paper, a ten-story high-strength steel composite K-shaped eccentrically braced frame (HSS-K-EBF) structure was firstly used for performance design and analysis based on a single bay EBF. The results show that the global structural model obtained by direct performance design of the single bay model cannot achieve the desired performance objectives. To this end, an improved PBPD method for the dual steel system was proposed considering the global effects of space frames. The elastic and elastic–plastic shear distribution relations were calculated for different bays of the frames including EBFs and MRFs. The performance objectives of the global structure were designed and evaluated more accurately by considering the over-strength contribution of shear links and the plastic development rate index ξ of energy dissipation members. The improved PBPD method was used to design the ten-story global HSS-K-EBF structure. The results of nonlinear dynamic time history analysis show that the improved PBPD method can ensure that the plastic damage distribution of energy dissipation members of different bays is more uniform and the plastic damage degree is more consistent with expectations.

Experiment and analysis on seismic performance of a self-centering Y-eccentrically braced frames structure

Conventional eccentrically braced frames (EBFs) exhibit significant residual deformations following major earthquakes, necessitating costly repairs for the damaged structures. This study proposed a novel self-centering Y-eccentrically braced frames (SC-YEBFs) system to enhance the seismic resilience. A theoretical mechanical model which takes into account its components is formulated to predict the lateral load behavior of SC-YEBFs. The pseudo-static experiments were conducted on four specimens, and the resulting observations and analyses demonstrate that the shear links effectively function as ductile fuses, dissipating a significant portion of the input energy to safeguard the main frame from damage. Furthermore, the self-centering joint exhibits a hinge-like behavior with remarkable self-centering characteristics. The structural reparability of all specimens was found to be exceptional during major seismic events. By increasing the initial prestress and sectional area of steel strands, the self-centering performance can be further enhanced. The damaged shear links could be easily detached by loosening bolts, and the consideration of prestress loss is nonnegligible to ensure an exceptional self-centering performance. The proposed theoretical model predicted the mechanical properties of SC-YEBFs, including lateral stiffness, energy dissipation, and self-centering mechanism, through a comparison with experimental results. Moreover, the theoretical model was utilized to propose an equivalent simulation method for simulating self-centering joint and shear link using Connector function in ABAQUS software, while establishing a simplified frame finite element model for further analysis.

Mechanical performance of completely GFRP-tendon-reinforced concrete slabs considering compressive-tensile membrane action

Presently, increasingly more concrete structures strengthened with glass-fiber-reinforced polymer (GFRP) tendons have been employed in practical civil engineering owing to outstanding advantages, such as anti-corrosion, cost-effectiveness, and ease of production. These structures have demonstrated unique characteristics and mechanical response compared to steel-tendon-reinforced concrete structures in both service and ultimate load-bearing states. Therefore, in this study, to analyze completely GFRP-tendon-reinforced concrete slabs under localized wheel pressure, loading tests were conducted on two full-scale fabricated frame structures while considering the influence of membrane action on the cover slab. The mechanical response of these structures was revealed using the obtained load-displacement curves, ultimate bearing capacity, and crack morphology. The membrane action mechanism of the slab under weak lateral constraints was studied through the finite element method. The method to determine the effective membrane region of the reinforced slab was discussed and the corresponding ultimate bearing capacity was proposed considering the compressive-tensile membrane action under different failure modes. This model provides a preliminary reference for the quantitative determination of the structural properties of GFRP-tendon-reinforced concrete slabs.

Algorithm-Driven Extraction of Point Cloud Data Representing Bottom Flanges of Beams in a Complex Steel Frame Structure for Deformation Measurement

Laser scanning has become a popular technology for monitoring structural deformation due to its ability to rapidly obtain 3D point clouds that provide detailed information about structures. In this study, the deformation of a complex steel frame structure is estimated by comparing the associated point clouds captured at two epochs. To measure its deformations, it is essential to extract the bottom flanges of the steel beams in the captured point clouds. However, manual extraction of numerous bottom flanges is laborious and the separation of beam bottom flanges and webs is especially challenging. This study presents an algorithm-driven approach for extracting all beams’ bottom flanges of a complex steel frame. RANdom SAmple Consensus (RANSAC), Euclidean clustering, and an originally defined point feature is sequentially used to extract the beam bottom flanges. The beam bottom flanges extracted by the proposed method are used to estimate the deformation of the steel frame structure before and after the removal of temporary supports to beams. Compared to manual extraction, the proposed method achieved an accuracy of 0.89 in extracting the beam bottom flanges while saving hours of time. The maximum observed deformation of the steel beams is 100 mm at a location where the temporal support was unloaded. The proposed method significantly improves the efficiency of the deformation measurement of steel frame structures using laser scanning.

Yield Behaviour of Welded I-Shaped Steel Cross-Sections

The limit behaviour of I-shaped welded steel cross-sections subjected to axial force, shear, and bending moment is a crucial matter to ascertain the reliability of framed structures constituted by non-standard beam elements. International standards provide an approximate solution to the problem, and other studies have proposed improved approximate formulations to ascertain the real features of the relevant cross-sections. The present paper is devoted to enhancing the problem of the limit behaviour of plane I-shaped welded steel cross-sections subjected to axial force N, shear T and bending moment M; therefore, new appropriate formulations are proposed in order to define suitable new domains, both in planes N,T, N,M, and M,T and in the space N,T,M. The material is assumed as elastic–perfectly plastic and the Von Mises limit condition is adopted as the resistance criterion. The elastic stresses are described by the Navier formula and the Jourawski formula. The limit stress condition related to the contemporaneous presence of the acting forces is defined as the one that, at each point of the cross-section, fulfils the Von Mises limit condition as equality. The formulation is rigorously devoted to factory-made welded I-shaped steel cross-sections. Some numerical examples are reported in the application stage and useful comparison are carried out, with the results being obtainable by the application of the classical known standard formulae, proving the reliability and effectiveness of the determined domains.

Kajian Struktur Rangka Batang Jembatan Wailola Besar Kabupaten Seram Bagian Timur

The Wailola Besar Bridge, which is located in Bula District, East Seram Regency, has a Warren truss type frame structure. However, unlike the truss used on other bridges, the truss on the Wailola Besar bridge has a larger size than the others. Because the span of the Wailola Besar bridge is 80 m, while the span of other bridges using the Warren truss type is a maximum of 60 m. The larger size than the other trusses makes the Wailola Besar bridge have a different truss from other trusses. The length of each horizontal bar is 6.65 m, while the maximum length for other bridges is 5 m. Then the purpose of this study is to determine whether the truss structure of the Wailola Besar bridge is capable of carrying the loads acting on the bridge, the method used is with the help of the SAP-2000 program to determine the truss forces then controlled with allowable voltage. In order to know whether the structure is able to withstand the forces acting. From the results of calculations with the help of SAP-2000 the rod forces acting on the largest truss structure are 11066.881 KN at constant loading and 12222.547 KN at temporary loading and the stress that occurs is 1742.82 Kg/〖cm〗^2. at constant loading and 1924.81 Kg/〖cm〗^2. The stress that occurs in the truss does not exceed the allowable stress.

A nonlinear structural pulse-like seismic response prediction method based on pulse-like identification and decomposition learning

Abstract Accurate prediction of structural responses under seismic action is important for the performance evaluation of structures. However, depending on the differences in the characteristics of ground motions, particularly whether they contain impulses, the seismic-response characteristics of structures may differ significantly. Hence, a new method, i.e., WD–AttDL, is proposed in this study to predict structural response under pulse-like ground motions. This method innovatively combines a wavelet decomposition-based velocity pulse-identification method with decomposition learning, where decomposed pulses and high-frequency features are used as inputs to the neural-network model, thus simplifying the identification of pulse features for the model. The decomposition learning module integrates different types of submodules, such as CNN feature-extraction, LSTM temporal-learning, and self-attention mechanism submodules. To reduce the nonlinear time-range analysis calculations required to generate training data, a screening method for impulsive ground motions based on time-series feature clustering is proposed. The accuracy and applicability of the proposed method are verified by numerically simulating three different cycles of reinforced-concrete frame structures and a three-dimensional masonry structure. Compared with existing structural seismic-response models, WD–AttDL synergistically integrates different modules and thus offers a higher prediction accuracy. In particular, it reduces the peak error of the predicted response, which is important for the evaluation of structural performance. Additionally, based on the response predicted by WD–AttDL, a vulnerability analysis of the structure under pulse-like seismic effects can be performed rapidly and accurately.