Frame System Research Articles

Evaluating and strengthening low-rise reinforced concrete buildings constructed in Nepal

In Nepal, the reinforced concrete (RC) frame system is commonly used to construct low-rise buildings. In last three decades, a significant number of such buildings were proportioned and constructed in accordance with Nepal National Building Code NBC 205:1994 and NBC 205:2012—also known as the Mandatory Rule of Thumb (MRT). In the aftermath of 2015 Gorkha Earthquake (Mw 7.8) which resulted in large scale social and economic losses, the efforts to formulate improved seismic design provisions led to the development of NBC 105:2020. Considering that MRT-designed low-rise RC frame buildings still constitute a significant part of existing building stock, this study is aimed to conduct a comparative seismic performance evaluation of several case study structures under a comprehensive set of ground motions. Using the nonlinear analysis and seismic fragility assessment of four low-rise RC frame buildings (designed using all three code versions), it is shown that the structural performance and seismic losses can be significantly reduced by following NBC 105:2020 provisions. Several retrofitting solutions are also explored to improve the seismic performance of buildings designed using MRT. It is shown that the concrete or steel jacketing of RC columns can significantly increase the lateral strength and energy dissipation, and reduce the damage probability of such buildings. Lastly, based on the developed results, a machine learning approach is employed to correlate the peak ground acceleration with structural drifts for convenient practical applications.

Reinforced ECC-UHPC-SCC composite modular framed shear wall systems under lateral cyclic loading

The shear strength and deformability of high performance reinforced composite framed shear wall systems made of Engineered Cementitious Composite (ECC), Ultra-High-Performance Concrete (UHPC) and Self-Consolidating Concrete (SCC) subjected to lateral cyclic shear loading to failure were investigated. A total of seven framed shear wall specimens were constructed using combinations of ECC or SCC wall, SCC frame and ECC or UHPC frame joints. The performance of such novel modular forms of walling systems were compared based on experimental results in terms of cracking, failure mode, hysteretic shear load-deformation response, shear load capacity, ductility, bearing capacity degradation, stiffness degradation, dissipated energy, viscous damping capacity, induced wall shear stresses and strain development characteristics. ECC walling system exhibited better structural performance compared to their SCC counterparts showing up to 40% higher load capacity forming significantly higher number of closely spaced diagonal cracks with up to 72% lower crack shear stress, 14% to 21% higher ductility, up to 2 times higher energy dissipation capacity and lower rate of stiffness/bearing capacity degradation through both hysteretic and damping actions. The incorporation of ECC and ECC or UHPC joint in frame significantly improved shear strength capacity of infill wall and overall framed shear wall system. ECC incorporated framed shear walls even with frames made of SCC and UHPC joints also exhibited superior performance. This study confirmed the superior performance of ECC material for the construction of reinforced framed shear wall with boundary frame made of ECC/SCC/UHPC combinations for better seismic resistance.

Strength and behavior of axially and eccentrically loaded built-up closed sections using four cold-formed steel open sections

Innovation in cold-formed steel framing systems is needed for opening flexibility and application in mid-rise buildings. Hence, this study proposes a closed built-up section using four cold-formed steel (CFS) open sections with a high load bearing capacity that potentially enables the development of high-performance cold-formed steel framing systems for these. The closed section by combining four open CFS sections using fasteners can effectively enhance the load capacity of the sections under axial loading. With a specially designed intersections gusset plate this built-up section offers more potential configurations of beam-column moment connections for CFS structures. First, a heuristic optimization was performed to identify a high-performance section based on the local and distortional buckling strengths using the finite strip method. Second, a test program was developed to investigate the load bearing capacity and failure behaviors of the optimized built-up closed section under axial and eccentric loading. Third, their load bearing capacities were compared with several other closed sections such as the rectangular hollow tube (RHS) of equal cross-sectional area or equal moment of inertia to highlight the high material efficiency. This study paved the groundwork for exploring high-performance cold-formed steel framing systems with this unique closed built-up section.

DESIGN OF REINFORCED CONCRETE STRUCTURE WITH ORDINARY MOMENT FRAME IN LOW SEISMIC REGION (CASE STUDY: MIDRISE SHOPPING BUILDING IN SINGKAWANG CITY)

This paper focuses on the design of a reinforced concrete structure for an eight-story shopping building in Singkawang City, located in a low to moderate seismic area. The study integrates relevant design considerations in response to the region's seismic conditions. Through structural analysis, the building is categorized as seismic design category B due to moderate seismic risk, leading to the selection of an ordinary moment-resisting frame system compliant with SNI 1726:2019. Emphasis is placed on the importance of using such a system to enhance ductility and prevent brittleness during earthquakes.The research emphasizes the need to design structures capable of withstanding various loads, including dead, superimposed dead, live, wind, and earthquake loads, particularly in West Kalimantan, known for its historically low to moderate seismic activity. Recent earthquake records highlight the necessity of earthquake-resistant design for safety and durability. Structural analysis confirms the building's stability against seismic forces, with a modal participation ratio meeting SNI 1726:2019 requirements, indicating robust response under seismic loads.The study also assesses inter-story drift and P-Delta effects to ensure they meet allowable limits, which is crucial for preserving structural integrity and preventing post-earthquake instability. A detailed reinforcement design following SNI 2847:2019 enhances structural strength and durability, especially when under seismic loading. The foundation design uses tailored hollow spun piles to provide sufficient bearing capacity and stability. This approach demonstrates resilience against potential seismic events in low-to-moderate seismic regions, highlighting the importance of integrating seismic design principles and ductility considerations for effective earthquake hazard mitigation.

High Speed Fighter UAV with Electric Coil Gun

The paper focus on "High-Speed Fighter Drone Using Electromagnetic Coil Gun and Dropping Mechanism" project represents a significant milestone in the realm of unmanned aerial vehicles (UAVs). This project aimed to design, develop, and demonstrate a cutting-edge high-speed fighter drone equipped with an electromagnetic coil gun and an advanced payload deployment mechanism. The primary objectives were to enhance drone maneuverability, achieve precision targeting capabilities, and enable efficient payload deployment, thus expanding the potential applications of UAV technology. This project involved an intricate blend of engineering, innovation, and technology integration. The drone's design and construction incorporated a lightweight yet durable frame, high-speed motors, and advanced flight control systems, ensuring exceptional agility and stability during flight. The electromagnetic coil gun, a pivotal component, was meticulously designed for precision targeting, delivering impressive accuracy and firing control. Moreover, the payload deployment mechanism, a vital feature of the system, was developed to ensure the precise and reliable delivery of payloads, expanding the drone's versatility across various domains, including defense, surveillance, and emergency response Throughout the project's lifecycle, rigorous testing, calibration, and data analysis were conducted to validate the drone's performance, accuracy of the electromagnetic coil gun, and efficiency of the payload deployment mechanism. The project yielded promising results, demonstrating the drone's exceptional flight performance, electromagnetic coil gun's precision targeting, and payload deployment's reliability. This project report provides a comprehensive overview of the project's objectives, methodologies, results, and significance. It explores the intricate system design, integration processes, testing procedures, and detailed analyses of outcomes. Furthermore, it discusses the challenges faced during development and the potential impact of this high- speed fighter drone in various industries. In conclusion, the "High-Speed Fighter Drone Using Electromagnetic Coil Gun and Dropping Mechanism" project represents a significant leap forward in UAV technology. Its successful realization opens up new possibilities for drone applications, promising advancements in precision targeting, payload deployment, and the overall versatility of UAVs in both civilian and military contexts

Innovative Point Cloud Segmentation of 3D Light Steel Framing System through Synthetic BIM and Mixed Reality Data: Advancing Construction Monitoring

In recent years, mixed reality (MR) technology has gained popularity in construction management due to its real-time visualisation capability to facilitate on-site decision-making tasks. The semantic segmentation of building components provides an attractive solution towards digital construction monitoring, reducing workloads through automation techniques. Nevertheless, data shortages remain an issue in maximizing the performance potential of deep learning segmentation methods. The primary aim of this study is to address this issue through synthetic data generation using Building Information Modelling (BIM) models. This study presents a point-cloud-based deep learning segmentation approach to a 3D light steel framing (LSF) system through synthetic BIM models and as-built data captured using MR headsets. A standardisation workflow between BIM and MR models was introduced to enable seamless data exchange across both domains. A total of five different experiments were set up to identify the benefits of synthetic BIM data in supplementing actual as-built data for model training. The results showed that the average testing accuracy using solely as-built data stood at 82.88%. Meanwhile, the introduction of synthetic BIM data into the training dataset led to an improved testing accuracy of 86.15%. A hybrid dataset also enabled the model to segment both the BIM and as-built data captured using an MR headset at an average accuracy of 79.55%. These findings indicate that synthetic BIM data have the potential to supplement actual data, reducing the costs associated with data acquisition. In addition, this study demonstrates that deep learning has the potential to automate construction monitoring tasks, aiding in the digitization of the construction industry.

Evaluation of Emulative Level for Precast Moment Frame Systems with Dry Mechanical Splices by Using Nonlinear Dynamic Analysis

Evaluation of Emulative Level for Precast Moment Frame Systems with Dry Mechanical Splices by Using Nonlinear Dynamic Analysis

Experimental and numerical investigation of hysteretic earthquake behavior of masonry infilled RC frames with opening strengthened by adding rebar-reinforced stucco

Adding a reinforced stucco layer to the masonry infill walls is a preferred method for strengthening RC frame system structures with an easy-to-apply method that does not require a long time, is economical, and does not require detailed and extensive workmanship. However, no research has been discovered as a result of the extensive literature review that investigates the effects of masonry-infilled RC frames strengthened with a reinforced stucco layer on the seismic performance of openings that must be due to architectural requirements such as doors, windows, installations, and similar ventilation systems. As a result, an experimental study was planned to investigate the effects of the dimensions and location of the opening in the masonry infill walls on the performance of the strengthening method with the reinforced stucco layer. The applied strengthening method increased the ultimate load capacity, initial stiffness, and energy dissipation capacity values of reinforced concrete frames with masonry infill walls by 83%, 226%, and 62%, respectively, but resulted in a 38% decrease in displacement-ductility ratios. The study found that the openings in the masonry infill walls harm the performance of the strengthening technique by adding a rebar-reinforced stucco layer and decreasing the success level. When the opening size increased, and the opening was located at the corner of the masonry wall, the performance of the applied strengthening technique was negatively affected and decreased. Furthermore, nonlinear numerical analyses of the experiments conducted as part of the study were performed using ABAQUS finite element software. The numerical analysis results were compared to the experimental results. It has been determined whether numerical analysis models are compatible with experimental results.

Clustering and optimization of nodes, beams and panels for cost-effective fabrication of free-form surfaces

Free-form surfaces are increasingly used in contemporary architectural designs for their unique and elegant shapes. However, fabricating these doubly curved surfaces using panel and frame systems presents challenges due to the shape variability of nodes, beams and panels. In this study, we propose a mesh-based computational design framework that clusters and optimizes these components together, reducing the shape variety of elements for free-form surfaces. Our method employs a vertex-based similarity metric to partition panels into user-defined groups and clusters beams based on edge lengths. A box-constrained optimization is introduced to achieve congruent faces and matching beam lengths while considering various functional constraints. Additionally, connection holes on node surfaces are clustered and optimized to allow their use at multiple locations. The practicality of our approach is demonstrated through the design and construction of a full-scale pavilion, resulting in a significant reduction in the shape variety of building elements.

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.

Performance study of eccentrically braced steel frames with core tube flange connection

This paper proposes a kind of assembly brace connections adapted to the core tube flanged column connection joint of the frame-brace structure, starting from the eccentrically braced frame structure in the steel frame system and designing and completing a set of proposed static tests of the eccentrically braced frame with the core tube flanged column connection joint. By conducting in-depth analysis and research at three levels, namely the seismic performance of the eccentrically braced frame system, the performance characteristics of the core tube type flanged column connection joints, and the performance of assembled brace connections, the study has yielded insights into the force mechanism and failure modes of the core tube type flanged column connection joints within the eccentrically braced frame system; the eccentrically braced frame system has been validated to possess good seismic performance by analyzing hysteresis curves, typical section strains, and bolt forces. These analyses have shown that the system can meet the seismic requirements. Moreover, the assembled brace joints were destroyed later than the braces, indicating that the assembled brace connection joints could fulfill the requirement of “strong joints.”

Environmental life cycle costs of steel moment frames utilizing endurance time method

This study aims to compare the Ordinary Moment Frame (OMF), Intermediate Moment Frame (IMF), and Special Moment Frame (SMF) systems in terms of life cycle cost, taking into account the environmental effects associated with the buildings. Minimizing environmental impacts is essential for achieving sustainable design. The assessment of environmental effects includes both the initial impacts related to building construction and the costs resulting from environmental damage caused by earthquakes over the building's lifespan. These environmental effects are quantified and translated into economic costs. To calculate life cycle cost while considering environmental effects, the proposed framework utilizes the Endurance Time (ET) method as the structural response model. The ET method allows for efficient analysis, facilitating multiple assessments and the exploration of different options. To conduct a case study, the OMF, IMF, and SMF systems are compared in 4, 8, and 12-story structures. Findings reveal that in the 4-story structure, the SMF system incurs higher environmental and life cycle costs, in addition to the initial cost. Conversely, the OMF system results in a lower total cost in the 4-story structure. However, for the 8 and 12-story structures, despite the SMF system's higher initial cost, it exhibits lower life cycle and environmental costs, ultimately leading to a lower overall total cost compared to the other two systems.

Experimental investigation of long-span cold-rolled aluminium built-up section portal frames: Unbraced columns and flexural-torsional buckling

The paper presents an experimental program on a structural system, consisting of three long-span portal frames. The primary structural members, including columns and rafters, were constructed using cold-rolled aluminium back-to-back built-up channel sections. The system configuration featured two bays of single-span cold-rolled aluminium portal frames connected in parallel by a series of purlins spanning between the rafters to create a free-standing structure. A total of three full-scale tests (Frame Tests 1,2 & 3) were conducted with two loading scenarios. Frame Tests 1&2, which were identical to ensure accuracy, were subjected to vertical loads only, while Frame Test 3 underwent testing with combined horizontal and vertical loads. In all the tests, the columns were unbraced. The main objectives of this paper are, first, to describe the test setups and observe the structural behaviours of the portal frame systems. Consequently, the ultimate capacities were determined, and the predominant failure modes of the portal systems were identified as flexural-torsional buckling of the unbraced columns. The paper also provides information on the mechanical properties of the aluminium alloy 5052-H36 materials used to fabricate the structural members and frame components, obtained from compressive and tensile coupon tests. Further, the elastic buckling loads of the columns in the frame systems are reported in this paper, as determined from the measured load-deformation curves. While this paper primarily delves into the behaviour of the cold-rolled aluminium portal frames with a focus on flexural torsional buckling failures of unbraced columns, the authors have also conducted a separate study on the same system. In that separate study, the portal frames with the columns predominantly restrained against flexural-torsional buckling were investigated to enhance the ultimate capacities of the portal frame systems.

Numerical Covariance Evaluation for Linear Structures Subject to Non-Stationary Random Inputs

Random vibration analysis is a mathematical tool that offers great advantages in predicting the mechanical response of structural systems subjected to external dynamic loads whose nature is intrinsically stochastic, as in cases of sea waves, wind pressure, and vibrations due to road asperity. Using random vibration analysis is possible, when the input is properly modeled as a stochastic process, to derive pieces of information about the structural response with a high quality (if compared with other tools), especially in terms of reliability prevision. Moreover, the random vibration approach is quite complex in cases of non-linearity cases, as well as for non-stationary inputs, as in cases of seismic events. For non-stationary inputs, the assessment of second-order spectral moments requires resolving the Lyapunov matrix differential equation. In this research, a numerical procedure is proposed, providing an expression of response in the state-space that, to our best knowledge, has not yet been presented in the literature, by using a formal justification in accordance with earthquake input modeled as a modulated white noise with evolutive parameters. The computational efforts are reduced by considering the symmetry feature of the covariance matrix. The adopted approach is applied to analyze a multi-story building, aiming to determine the reliability related to the maximum inter-story displacement surpassing a specified acceptable threshold. The building is presumed to experience seismic input characterized by a non-stationary process in both amplitude and frequency, utilizing a general Kanai–Tajimi earthquake input stationary model. The adopted case study is modeled in the form of a multi-degree-of-freedom plane shear frame system.

COMPARISON BETWEEN SMF AND SPSW STEEL BUILDING FOR MIXED-USE RESIDENCE USING THE AHP METHOD

The objective of this work is to compare the Special Moment Frame (SMF) system and the Steel Plate Shear Wall (SPSW) system using the AHP multi-criteria comparison method with the two Seismic Load Resisting Systems (SFRS). From the linear static analysis, dynamic analysis, and nonlinear static analysis (Pushover), representative characteristics of each Seismic Force-Resisting System (SFRS) are determined. These characteristics include the structure's self-weight, target displacement, floor drifts, and seismic response modification factor (R). As a result, two buildings are obtained with different SFRS that comply with the design of their elements and checks according to the regulatory requirements. After determining the capacity curve of each Seismic Force-Resisting System (SFRS) and assessing the performance level of the buildings, the conclusion is drawn that the Special Plate Shear Wall (SPSW) system is more suitable and advantageous compared to the Special Moment Frame (SMF) system. This preference is due to the SPSW system's ability to provide ductility, which translates into higher energy dissipation capacity, and stiffness, which leads to reduced floor drifts in the building.

A new performance‐based seismic design method using endurance time analysis for linked column frame system and a comparison of structural systems and seismic analysis methods

SummaryThis paper presents a new performance‐based seismic design method for the design of repairable linked column frame (LCF) and linked column system (LCS). Currently, the biggest problem of these systems is the lack of a simple and practical design method that leads to the design of optimal models with sufficient seismic capacity. The interaction of the primary and secondary systems, changing the lateral load pattern during an earthquake, and the implementation of the target performance objectives have complicated the design of these systems. The evaluations carried out in this research show that the rotation of link beams must be controlled in the design. Therefore, the ultimate plastic rotation of links is determined to be 0.01 rad for the seismic intensity of design base earthquake and 0.015 rad for maximum considered earthquake. The results show that the models designed using the presented method are optimal, have sufficient seismic capacity, and achieve the target performance objectives. In addition, although previous researches have shown that these systems have a suitable seismic behavior, their seismic behavior have not been compared with other structural systems. Comparing can show the behavioral characteristics of a new structural system; hence, the elastic and plastic behavior of the LCF and LCS models have been compared with other common steel structural systems using all analysis methods. Moreover, in the presented method for the design of LCF and LCS systems, nonlinear time history analysis using the endurance time method (ETM) is used, and due to the newness of the endurance time method, its results are compared with the median results of nonlinear time history analysis at different seismic hazard levels and incremental dynamic analysis (IDA), in 45 samples. The results show that the endurance time analysis is a reasonable and efficient method, and in this comparison, the difference between the results of ETM and IDA methods is 6% on average.

Experimental Study of Novel Demountable Shear Connectors for Steel-concrete Composite Buildings

Sustainable composite structures in building construction are assembled using demountable structural elements that can be reused in the circular economy. The current research and development project, in cooperation with Budapest University of Technology and Economics and KÉSZ Group, bim.GROUP Ltd., Hungary, aims to design a novel demountable steel-concrete composite slab and frame system for buildings. The key component of this construction is the demountable shear connector. In the current research, novel bolted shear connectors with embedded bolts and threaded rods are developed and studied that can fit the applied technology of the industrial partner. One of the leading aspects of this connection is the consideration of bolt hole clearance, since it occurs initial slip and stiffness reduction of the composite beam. In the first phase of the research program, demountable and economical structural details were developed, which can reduce the stiffness reduction with the proper resistance and ductility features. To study the behavior of these shear connections, a push-out experimental program was designed and completed in March and April 2023. It is observed that novel shear connectors have a proper behavior with sufficient resistance and ductility, which is applicable according to the Eurocode 4 standard and fits the objectives of the research and development project. In the paper, the developed structural details and the push-out experimental program are presented with general results and statements besides a detailed evaluation of a specified specimen type.

Numerical Simulation of Soil–Structure Interaction of RC Frame

An Attempt has been made to study the effect of soil media on the response of RC frame structure. Therefore, the present work focuses on the implementation of a two dimensional finite element model of reinforced concrete frame and pile foundation system which explicitly incorporates the soil response. The superstructure members have been represented by means of three-node isoperimetric beam elements with three degrees of freedom per node. The soil mass is idealized by the eight-node isoperimetric quadrilateral element at the near field and five nodes isoperimetric infinite element to simulate the far-field behavior of the soil media. The applicability of this model was demonstrated by analyzing a multi-story building. The results have shown that the influence of the soil behavior on the overall response of the structure.

Experimental and numerical studies on friction energy-dissipating combination chord of staggered truss

Staggered truss framing systems have the problem of insufficient energy dissipation capacity in high intensity areas. To improve this situation, this paper proposes to replace the top chord of the staggered truss with a combination chord for frictional energy dissipation. Two groups and a total of four 1:2 scaled friction energy-dissipating combination top chord specimens were designed and fabricated, and hysteretic performance tests were carried out on them under low cycle reciprocating loads. It was investigated how high-strength bolt pre-tightening force and bolt layout affected the capacity of the combination chord to dissipate energy. The experimental results show that the hysteresis curve of the combination top chord for friction energy dissipation almost presents an ideal rectangle, and its energy-dissipating capacity is very strong. The combination top chord's capacity for friction energy dissipation increases with the increasing pre-tightening force of the high-strength bolt, but its stability for energy dissipation decreases. When the bolt layout is the staggered arrangement of single and double bolts, the initial energy dissipation and cumulative energy dissipation are weaker than that of the uniform arrangement of double bolts. Then, the friction energy-dissipating staggered truss with a sliding bottom chord was proposed to improve the load state of the diagonal web member in the staggered truss. The numerical simulation results show that the overall energy dissipation capacity and lateral bearing capacity of the staggered truss with the bottom chord sliding are 4.0% and 24.5% higher than those of the staggered truss with the top chord sliding.

Perencanaan dan Analisis Keefektifan Penempatan Dinding Geser terhadap Perilaku Struktur dengan Software ETABS

The rise of high-rise building development is due to land limitations and also the soaring population. The vulnerability of high-level building structures to lateral forces, one of which is the earthquake force, requires that high-level building structures be able to withstand the lateral forces that occur. There are several structural systems in resisting lateral forces, including moment-bearing frame systems and shear wall systems. The purpose of this research is to compare the structural analysis of three alternative plans with different shear wall placements. The structural analysis uses ETABS software that refers to SNI 1726: 2019. The results of the research from three alternative models, show that the smallest deviation value towards the X-axis and Y-axis, and the average deviation value is 19.787 mm in the X-direction and 17.220 mm in the Y-direction. The requirements for a dual system with a special moment-bearing frame are also met in alternative planning 2 with a contribution of forces acting on the portal of 36.7340% in the X-direction and 31.1996% in the Y-direction. The amount of mass participation that occurs is above 90% and in accordance with the requirements specified by SNI.