Member Forces Research Articles

Inductive graph‐based long short‐term memory network for the prediction of nonlinear floor responses and member forces of steel buildings subjected to orthogonal horizontal ground motions

Inductive graph‐based long short‐term memory network for the prediction of nonlinear floor responses and member forces of steel buildings subjected to orthogonal horizontal ground motions

Seismic performance of pentagonal type aluminum alloy suspen-dome structure with large opening

Prestressing technology is an effective way to enhance the mechanical properties of space structures. In view of this, a new pentagonal type aluminum alloy suspen-dome structure with large opening is proposed in this paper by introducing the lower cable support system into the aluminium alloy single-layer reticulated shell structure. The seismic performance of this new structure is investigated using time-procedure analysis. Firstly, the effects of rise-span ratio, thickness-span ratio, prestressing level, horizontal radius factor for lower chord nodes and roof loading on the free vibration characteristics of the structure with different supporting stiffness are investigated. The distributions of internal forces and displacements of members of overall structure considering lower support and roof structure only are analyzed. Subsequently, the dynamic response of the structure under seismic combinations of different dimensions and directions is investigated, and reasonable combinations that should be considered for simplified analyses are derived. Furthermore, seismic internal force coefficients are introduced to assess the degree of seismic effects on various types of members. On this basis, parametric analysis of the seismic performance of the structural performance is conducted and quantitative assessment of the sensitivity of the parameters is carried out. Additionally, the free vibration characteristics and dynamic performance of steel and aluminium suspen-dome are compared. The results show that considering the supporting structure weakens the structural stiffness while increasing the structural dynamic response; reasonable values of key parameters in the seismic design of the structure are obtained; and the rise-span ratio and thickness-span ratio are important influencing factors of the seismic performance of the structure. Besides, the internal forces of members in aluminium alloy suspen-dome are less affected by seismic effects than those in steel suspen-dome, and the new structure has good seismic performance.

Conservation and Divergence of PEPC Gene Family in Different Ploidy Bamboos.

Phosphoenolpyruvate carboxylase (PEPC), as a necessary enzyme for higher plants to participate in photosynthesis, plays a key role in photosynthetic carbon metabolism and the stress response. However, the molecular biology of the PEPC family of Bambusoideae has been poorly studied, and the function of its members in the growth and development of Bambusoideae is still unclear. Here, we identified a total of 62 PEPC family members in bamboo. All the PEPC genes in the bamboo subfamily were divided into twelve groups, each group typically containing significantly fewer PEPC members in Olyra latifolia than in Phyllostachys edulis, Dendrocalamus latiflorus and Dendrocalamus brandisii. The results of an intraspecific and interspecies collinearity analysis showed that fragment replication and whole genome replication were the main driving forces of bamboo PEPC members. Furthermore, the Ka/Ks values of collinear genes showed that bamboo PEPC experienced purification selection. In addition, the promoter region of PEPC genes contains cis-acting elements related to light response, plant hormone response and response to stress. An analysis of the expression levels of the PEPC family in different developmental stages and tissues of bamboo shoots has shown that PhePEPC7, PhePEPC9 and PhePEPC10 were highly expressed in the leaves of non-flowering plants and culms. Furthermore, PhePEPC6 was significantly upregulated in leaves after GA treatment. Further research has shown that PhePEPC6 was mainly localized in the cell membrane. This provides a solid bioinformatics foundation for further understanding the biological functions of the bamboo PEPC family.

Morphological analysis of a novel scissor-type deployable cable dome structure

A novel deployable scissor-type strut cable dome structure was proposed, which can improve the lateral stiffness of the traditional cable structure and achieve the characteristics of fast unfolding and closing during construction. However, the geometric stability and optimal initial prestressing theory of traditional cable dome structures cannot be applied to the new structure. Based on the equilibrium matrix theory, the geometric stability analysis was conducted and the number of self-stress modes, mechanism displacement modes, and feasible prestress modes was calculated. Then, the formula for the initial prestress distribution of the structure was derived based on the node equilibrium equation. Furthermore, the geometric stability and initial prestress distribution of the structure with different rise-to-span ratios, number of circumferential struts, and hoop cables were studied. Finally, the dynamic properties of the structure are explored by finite element simulation. The analysis results show that the structure has excellent structural stability. The rise-to-span ratios, the number of circumferential struts, and hoop cables are the important factors affecting the geometric stability and the initial prestress distribution. The rise-to-span ratios have no effect on the number of structural modes, while the number of circumferential struts and cables will cause significant changes in the number of self-stress modes. The internal force of the structural members decreases with the rise-to-span ratio and the number of circumferential struts increases, and the number of circumferential struts has the greatest influence on its internal force. The structural natural frequency exhibits a dense distribution, which indicates that the structure has good stiffness. In summary, the research has provided an idea for the application of the deployable scissor-type strut cable dome structure as a new structural system in the field of structural engineering.

Component tests and numerical simulations of 3D steel frame structures for progressive collapse

This paper presents a comprehensive study on three-dimensional steel frame structures subjected to progressive collapse, drawing insights from a full-scale steel frame substructure test. The investigation encompasses connection component tests and numerical simulations, focusing on extended end plate and double-angle cleat connections employed in the substructure test. The mechanical properties of the connection components were tested, forming a basis for defining component properties in subsequent connection models. Finite element (FE) models of the test substructure were developed, utilizing hybrid elements for the steel frame part, which include beam, connector, and spring elements based on the component method. To simulate reinforced concrete slabs, a combination of refined solid elements and simplified shell elements was employed. The former accurately captures detailed failure modes, while the latter efficiently simulates the collapse behavior of large-scale steel frame structures. Validation of the established models against test results encompassed load-displacement responses, internal forces in structural members, and failure modes. The validated FE models were then utilized to analyze and discuss the contributions of various structural components in resisting progressive collapse. Specific focus was placed on the development of load-resisting mechanisms in the floor slab and the influence of beam-column connection types on structural behavior. The paper explores the role of bracing systems in a building in resisting progressive collapse. Additionally, it evaluates the effectiveness of the restraint systems used in the test, shedding light on their ability to accurately reflect real restraint effects from the surrounding structure. The findings presented herein contribute valuable insights to the understanding of progressive collapse behavior in steel frame structures, with implications for robustness design of multi-story steel buildings.

Study on interior beam–column joint sub-assemblage under bi-directional loading using finite element analysis

Purpose The purpose of this paper is to study the shearing performance under bi-directional loading of an interior beam–column joint (BCJ) sub-assemblage using the finite element analysis (FEA) tool (midas fea), validated in this research. Design/methodology/approach The BCJ can be defined as an essential part of the column that transfers the forces at the ends of the members connected to it. The members of the rigid jointed plane frame resist external forces by developing twisting moment, bending moment, axial force and shear force in the frame members. On the type of joints, the response to the action of lateral loads depends on reinforced concrete (RC) framed structures. The joint is considered rigid if the angle between the members remains unchanged during the structural deformation. This work examined the shear deformation, load displacement and strength of a non-seismically detailed internal concentric RC joint using non-linear FEA. The bi-directional loading imposes the oblique compression zone on one joint corner. This joint core’s oblique compression strut mechanism differs significantly from that under unidirectional loading. The numerical results are compared with experimental results in this study, with the data published in the literature. Findings Numerical analysis results show that, in the comparative study of numerical and experimental values, the FEA tool predicts the behaviour of the RC BCJ well. The discrepancy between the experimental and numerical results amounts to 6 to 12% end displacement of the beam, 7% resultant joint shear force, 4.23% column bar strain and 0.70% hoop strain. Originality/value The current code of practice describes the joint sub-assemblage behaviour along the single axis individually. In the non-orthogonal system, the superposition of the two axes for joint space results in overlapping the stresses and, hence, the formation of the oblique strut. This may result in a reduction in the joint capacity under bi-directional loading. The behaviour must be explored in depth, and an attempt is made for further exploration.

Transmission length of multiwire tendon in existing post-tensioned concrete structures

The paper presents unique research on real-scale post-tensioned concrete crane girders dismantled from an existing hall structure. The study aimed to determine the transmission length for bonded prestressing tendons in an anchorage failure situation, a critical factor for proper assessment of the safety of many building structures, mainly those built between the 1950s and 1980s. The results of the tests indicated the feasibility of prestressing force transmission from a 12Ø5 mm Freyssinet-type tendon to the element via bond stress, with implications extendable to the other 18Ø5 mm tendon type prevalent at the time. The key factor affecting transmission efficiency is the quality of tendon duct grouting, with good quality cement injection resulting in transmission length as short as 800 mm. Furthermore, a computational model for the transmission length of prestressing force in post-tensioned concrete members has been developed similarly to the Model Code 2020 for pretensioned concrete. The level I of approximation enables quick transmission length estimation, whereas refined analysis is possible with the level II approach. The developed model and the research findings facilitate a comprehensive assessment of the post-tensioned concrete members in anchorage or tendon failure scenarios. As a result of the analyses carried out, optimal strategies for the further use of the structures can be proposed, fostering a step towards sustainable management.

On the identification of the elastic modulus and axial force of beam members with unknown boundary conditions using modal information

The axial force of beam members with unknown boundary conditions can be estimated by using vibration measurements, and this method necessitates the real elastic modulus of the members to produce accurate estimations. However, in engineering practice, the value of the elastic modulus of such members differs from the designed value owing to material degradation and structural damage. In addition, the elastic modulus of the beam structure may have a significant impact on the identification accuracy of axial force. Therefore, this study develops a methodology for simultaneously estimating axial force and elastic modulus within axial force members of structural systems, based on measurements of multiple natural frequencies and mode shapes. First, an improved vibration formula for the Timoshenko beam under axial load is obtained using the energy approach. Then, based on the proposed dynamic equation, the axial force and elastic modulus of the beam are discovered to have a linear relationship when the modal information of the structure is known. Further, using this linear relationship, a method to identify the axial force and elastic modulus of the beam member under unknown boundary constraints is proposed. Finally, the applicability and accuracy of the proposed method are validated by many numerical and experimental tests, and excellent estimates of the axial forces and elastic modulus are achieved.

Seismic response of braced excavation wall supporting deep sand layer using dynamic centrifuge tests

This paper presents the dynamic centrifuge model tests to investigate the seismic performance of a 24.8 m deep braced diaphragm wall supporting dry sand backfill soil at 40 g level acceleration. The model tests aim to determine the acceleration response of the backfill, seismic earth pressures acting on the wall, and the dynamic increment of the structure's inner force for sand backfills with different relative densities. Particularly, the horizontal seismic coefficient, earth pressure distribution, and dynamic thrust are analyzed in detail. Based on the experimental results, the dynamic thrust development is consistent for peak ground accelerations at bedrock less than 0.12 g and 0.10 g for relavitve densities of 78 % and 54 %, respectively. However, the dynamic thrust starts to increase when the bedrock acceleration exceeds this threshold. Moreover, the varying trend of dynamic thrusts under ground input motion employed during at the initial excitation differs from that of the succeeding input motions, likely due to the changes in relative density caused by backfill disturbance from sequential excitation. The increasing rate of increase on the dynamic thrusts among Northridge, Kobe, and artificial excitations was changed with the amplitude of the acceleration response. Lastly, the wall bending moment and strut axial force increase by up to 97.3 % and 12.9 % of the maximum value of member force on the at-rest condition due to earthquake loading.

Study on prestress distribution and structural performance of heptagonal six-five-strut alternated cable dome with inner hole

The cable dome structure is a highly efficient prestressed space structure with reasonable force, attractive shape, and large spanning capacity. It is increasingly widely used in stadiums, exhibition halls, terminals, and other large-scale public buildings and the roof structure of various transport hub projects. To solve the problem of weak overall structural stability of the traditional cable dome structure, a new type of prestressed space structure is proposed - heptagonal six-five-strut alternated cable dome with an inner hole. The composition of the structural system was given and a theoretical study of the distribution of structural prestress was carried out; based on the symmetry and periodicity conditions, the initial prestress distribution of the structure was accurately calculated using the node balance method, and the formulae for the geometric parameters of the structural cable-strut were derived; the numerical model was established by using the finite element software ANSYS 2022 R1, and the force characteristics of the structure under full-span uniform load, half span uniform live load, wind load, and temperature were studied. The effects of structural prestress, overall shape, and support stiffness, totaling three categories and six parameters, on the structural mechanical performance of the internal force of the member, node displacement, and support reaction force were analysed in detail and the sensitivity of the parameters is assessed quantitatively, accordingly, the values of the main design parameters such as thick-span ratio are given as suggestions. The analysis results show that the new structural system has a high load-carrying capacity and deformation resistance, and its proposal provides a new scheme and new ideas for the selection and design of the cable dome.

Self-centering multiple rocking core systems for mitigating higher mode effects

The structural member forces of mid-story and high-rise self-centering energy-absorbing dual rocking core (SEDRC) systems can be significantly aggravated by higher mode effects. This study aims to introduce the multiple rocking mechanisms into the SEDRC system and propose the self-centering multiple rocking core system (denoted as SMRC system) to reduce the structural member force demands resulting from the higher mode effects. The working principle of the SMRC system is discussed. The performance-based design (PBD) procedures for the SMRC system are presented. The comparative dynamic history analyses are conducted on a 9-story SMRC and two 9-story SEDRC systems. Incremental dynamic analyses (IDAs) are carried out to investigate the dynamic behaviors of the considered systems under increasing seismic intensities. The accuracy of the developed designed procedures is verified with the evidence that the developed SMRC system can achieve the design displacement under design earthquakes. The multiple rocking mechanism can efficiently mitigate structural member force demands caused by the effects of higher mode. The SMRC system can achieve better seismic performance with lower structural member force demands than the SEDRC systems when the earthquake intensity is not higher than the maximum considered earthquakes (MCE). Nevertheless, the SMRC system shows worse performance than the SEDRC systems in resisting structural collapse when the intensity is higher than MCE, which could be a research gap for further investigations.

Stability Analysis of “321” Prefabricated Highway Steel Truss Bridge

The “321” prefabricated highway steel truss bridge is widely used for highway rescue, disaster relief, and emergency traffic. This paper uses a 33 m double-row monolayer “321” prefabricated highway steel truss bridge to analyze its mechanical properties and component stability. The actual traffic flow capacity of a total weight of 53.32 tons is used in this study. The results show that the maximum internal force in the truss chord (including the stiffening chord) occurs in the middle span section when a centrally distributed load is applied. Meanwhile, the maximum internal force of truss diagonal members and truss vertical bars appears at the fulcrum section. Under the eccentrically distributed load, the maximum internal forces of truss chords (including stiffening chords) appear in the middle span section, which is closest to the vehicle load, while the maximum internal forces of truss diagonal members and truss vertical bars appear in the fulcrum section, which is closest to the vehicle load. While the maximum internal forces under the eccentrically distributed load are greater than the maximum internal forces under the centered-layout load, under the vehicle load, truss chords (including stiffening chords) are prone to buckling instability, and the buckling mode is mainly reverse out-of-plane buckling. The inclined members of the truss are prone to buckling instability, and the buckling mode is mainly the combination of out-of-plane bending and two-way out-of-plane bending. Truss vertical bars have good stability and are not easy to buckle. The main conclusions of this paper can provide references for the optimal design and operation safety of prefabricated highway steel truss bridges.

Yoke-Type Elasto-Magnetic Sensor-Based Tension Force Monitoring Method for Enhancement of Field Applicability.

Tension members are key members that maintain stability and improve the strength of structures such as cable-stayed bridges, PSC structures, and slopes. Their application has recently been expanded to new fields such as mooring lines in subsea structures and aerospace fields. However, the tensile strength of the tension members can be abnormal owing to various risk factors that may lead to the collapse of the entire structure. Therefore, continuous tension monitoring is necessary to ensure structural safety. In this study, an improved elasto-magnetic (E/M) sensor was used to monitor tension force using a nondestructive method. General E/M sensors have limitations that make it difficult to apply them to operating tension members owing to their solenoid structure, which requires field winding. To overcome this problem, the magnetization part of the E/M sensor was improved to a yoke-type sensor, which was used in this study. For the development of the sensors, the numerical design and magnetization performance verification of the sensor were performed through eddy current solution-type simulations using ANSYS Maxwell. Using the manufactured yoke-type E/M sensor, the induced voltage signals according to the tension force of the specimen increasing from 0 to 10 tons at 1-ton intervals were repeatedly measured using DAQ with wireless communication. The measured signals were indexed using peak-to-peak value of induced voltages and used to analyze the signal change patterns as the tension increased. Finally, the analyzed results were compared with those of a solenoid-type E/M sensor to confirm the same pattern. Therefore, it was confirmed that the tension force of a tension member can be estimated using the proposed yoke-type E/M sensor. This is expected to become an effective tension monitoring technology through performance optimization and usability verification studies for each target tension member in the future.

Parameterization of Maxwell - Cremona Diagram for Determining Forces in Elements of a Scissors Truss

An analysis of changing patterns of the values of member forces in a scissors truss, depending on the position of connections of its lower chords to the upper chords, is performed. Exploring effective truss structure designs in terms of balanced combination of maximum strength and minimum weight is a sustainable approach to a more rational use of building materials and the development of green construction. This determines the relevance of this area of research. The analysis of configurations of the truss under study was performed using the parameterized Maxwell - Cremona diagram. Such diagram is a visually informative tool in presenting the calculation results and it fully reflects the relationship between the member forces and the parameters of the structure. The research process was performed using the MS Excel spreadsheet editor. This eventually developed into a software tool for finding effective scissors truss designs, which has full potential for further improvement and development. Thus, the functionality of the tool can be easily expanded to designing scissors trusses made of various structural materials, as well as with various crosssectional shapes of its elements. The proposed approach to the calculation of such structures can serve as a basis for parameterization of trusses with other types of web.

Comparison of Seismic and Wind Actions on Medium to High-Rise Buildings in Muscat, Oman

This study is a comparison of wind and seismic loads on medium and high-rise buildings in Muscat, Oman. It uses the proposed Omani Seismic Code and Eurocode EN1991 for seismic and wind calculations, respectively. Muscat falls under Zone-1 in the Omani seismic code and experience basic wind speed of 30 m/sec. The research investigates buildings with varying aspect ratios (1:1 and 1:2), heights (11, 15, and 19 stories), and structural layouts (frame only, core shear wall, and corner shear wall), using ETABS for structural analysis. The findings reveal that seismic actions are generally more significant than wind actions for buildings in Muscat. In frame-only structures, wind-induced base shear ranges from 16%-33% for 1:1 aspect ratio and 21%-43% in the x-direction and 10%-20% in the y-direction for 1:2 aspect ratio, when compared to seismic actions. This difference decreases with increasing building height. Incorporating shear walls notably reduces the maximum lateral displacement across all scenarios, with core-located walls being most effective, leading to a 49% reduction in lateral displacement. Shear walls also substantially mitigate first-story column shear forces and bending moments. The study concludes that seismic actions are more critical than wind actions in Muscat for simple moment-resisting frame systems. Additionally, using shear walls in these buildings is highly beneficial for controlling lateral displacements and reducing member forces.

Analysis and Design of Superstructure of Bridge Built Through Engineering College Premises

Abstract: The earlier publication from the authors focused on “The bridge through the college” which highlights how contracts and agreements signed many decades ago have to still be respected and fulfilled. A public highway planned to originally be laid on top of a filled-out irrigation canal passing through the campus of a college that commenced in 1977 was later replaced with an elevated bridge that was completed in 2023 and is now open to the public. The first part of the two-stage manuscript elaborated on the conception of the bridge, the general layout, geometry, and construction of this reinforced concrete girder bridge. The challenges associated in the process of engineering and construction as well as the opportunities missed were discussed. The second part of this study details the analysis process of the girders, the static and dynamic bridge loads considered, the code specifications and guidelines followed. The results of the analyses present the strength and service level member forces the bridge girders and slab are subjected to, and the design governing load combination envelopes. The study presents the superstructure girder designs, slab designs and the design methodology followed overall.

Experimental study and numerical analysis on the failure mode of staggered truss framing system

To investigate the seismic performance of staggered truss framing system under different failure modes, two trusses were designed according to the capacity design method. Then, two models with a scale of 1/2.5 were made and subjected to quasi-static tests. The hysteresis curve, stiffness, energy dissipation, and ductility coefficient of the two models were analyzed. The test results show that the specimen designed for chord failure has better seismic performance than that designed for diagonal web failure. The ultimate drift ratios of the two specimens are both less than 1.5%, indicating that the deformation ability of the staggered truss is insufficient. By analyzing the relationship between the plastic hinge rotation and the drift ratio of the truss, it is suggested that the limit value of the drift ratio of the staggered truss framing system should not exceed 1.5%. The yield-bearing capacity calculated by considering the composite effect of the chord and floor slab is closer to the test results than that calculated without considering the composite effect, indicating that the composite effect of the chord and floor slab should be considered when designing the trusses. Through the numerical analysis, it is recommended to take a minimum amplification factor of 1.3 for the internal force of web members to realize the purpose of chord failure.

Implicações de um programa de 8 semanas de treinamento da força e da flexibilidade sobre os sintomas depressivos em indivíduos com idade entre 60 - 65 anos

The psychological aspects are areas of study with ample importance for the third age and as well as significant improvements in the biological dimensions are told, research point positive effect on the psychological dimensions. Studies suggest that the aged ones if show overwhelming for problems that involve the health. From the moment that the health is reached the concerns in what start it says respect the individuals to become incapable, changedding itself into not motivated individuals and without interests, and of this form reaching them in such a way in the psychological aspect how much in the physical aspect. Methods: One is about a transversal analytical study. The sample was formed by 23 women and 7 healthful sedentary men, who had been submitted to a program of training of force of inferior and superior members and flexibility (emphasis in the flexibility of the trunk). For the evaluation of the depression, a described questionnaire for FIATARONE was used (1996). This instrument consists of 30 related questions the satisfaction with the life and states of spirit of the individual. The total number of negative points was considered, that is, all those answers that are associates the depression feelings. The analysis used statistics to measure the level of significance between daily pay and after-test of the evaluation of the depression was the test of McNemar, that tests given made use in contingency table 2x2, in order to compare ratio of two pairs groups, where the concordant pairs and the opponents in relation are observed the two treatments. Results: The use of the test of McNemar for the comparison enters the collected data in the daily pay-test and after-test program of physical activity, evaluating the depression, demonstrated not to have significant difference in none of the thirty 0 variable that the applied test composes. The study it demonstrated not to collaborate with this psychological state, assuring to be unsatisfactory the point in such a way to present level insignificant for the men how much for the women. This result was observed in both the sorts. Conclusions: The study it demonstrated not to collaborate with this psychological state of depression, being assured to be unsatisfactory the point in such a way to present level of insignificant for the men how much for the women.

The Influence of the Variation in Arch Height of the Main Tayan Bridge on the Member Forces

The height of the bridge arch significantly impacts the strength and structural efficiency. Research on the height of the Tayan Bridge arch was conducted to determine the values and behaviour of member forces, structural weight, and deflection and to design the optimal arch height geometry. This research involved five variations of the arch height. The bridge structure was modelled using AutoCAD software. Relevant bridge loading data based on the SNI 1725-2016 standard was inputted into AutoCAD for structural design, and then the structure was modelled and analysed using SAP2000. The analysis results provided information on the bridge weight, deflection, and member forces. The analysis results were then compared with the bridge arch height, and this comparison was presented in the form of graphs. From the analysis results, it can be concluded that the bridge arch height has a positive linear relationship with the bridge weight. Tensile and compressive forces exhibit opposite behaviour. Increasing the arch height with constant value results in weight, deflection, and member force variations. Constantly expanding the arch height also does not lead to an increase in the stiffness of the bridge. Structurally, the optimal arch height is 42.134 meters.

Estimation of tension force in tension members using GRU algorithm based on yoke-type elasto-magnetic sensor data

Estimation of tension force in tension members using GRU algorithm based on yoke-type elasto-magnetic sensor data