Design Of Frame Structures Research Articles

Investigation on the progressive collapse resistance of three-dimensional concrete frame structures reinforced by steel-FRP composite bar

Compared with conventional steel bars, steel-FRP (fiber reinforced polymer) composite bars (SFCBs) have distinctive post-yield stiffness, and the high efficiency of SFCBs in enhancing the progressive collapse resistance of concrete frames has been confirmed by recent quasi-static experimental studies on SFCB beam–column subassemblages. However, the realistic progressive collapse of structures is a dynamic process, and the three-dimensional (3D) effects are essentially important for determining the collapse response. In this study, numerical models are built to explore the progressive collapse behavior of 3D frame structures reinforced by SFCBs. The static and dynamic capacities of five SFCB frames and one reinforced concrete (RC) frame are compared under different column–removal cases. Results show that by virtue of the post-yield stiffness, the static load factors of SFCB frames are much larger than those of RC frames at the same deformation, proving that SFCB frames have better robustness against collapse failure than RC frames. After the dynamic removal of columns, all RC frames are subjected to progressive collapse failure, while SFCB frames can successfully complete the dynamic load redistributions and quickly reach a steady state. Further, the dynamic increase factor (DIF) of SFCB frames is proposed based on the ratio of maximum dynamic flexural responses to static flexural responses of beam joint sections under the same gravity loads (1.2 times dead load plus 0.5 times live load), and the conservative DIFs of 1.55 and 1.3 are recommended for a corner column–removal case and the other single column–removal cases, respectively. Finally, parametric analyses are conducted to reveal the effect of beam longitudinal reinforcement ratio, beam span-to-depth ratio, and dynamic duration for the column removal on the progressive collapse resistance of SFCB frames. The results lay a foundation for the progressive collapse design of 3D SFCB frame structures.

Seismic vulnerability analysis for shallow-buried underground frame structure considering 18 existing subway stations

The variability of structural engineering parameters is not accounted for in available literature on seismic vulnerability of underground frame structures. This study investigates the seismic vulnerability of 18 existing subway stations with different site condition, structural stiffness, reinforcement ratio and buried depth employing two-dimensional (2D) finite element analysis considering soil-structure interaction. The peaks of structure inter-story drift ratio under different earthquake intensity of different ground motion records are obtained from non-linear dynamic time-history analysis. Taking the inter-story drift ratio as the damage measure (DM) and the peak ground acceleration (PGA) as the ground motion intensity measure (IM), the seismic vulnerability curves of 18 subway stations are constructed. The comparison of seismic fragility curves of different subway stations demonstrates that site conditions are critical to the post-earthquake structure probability of failure. Furthermore, representative seismic fragility curves are established based on the data collected form the computed results of 18 subway stations, which can aid in evaluating the seismic performance of existing urban underground frame structures in China. The results of this study can provide reference for the performance-based seismic design of urban underground frame structures.

Performance-based seismic design of RC frame structure with energy dissipative cladding panel connection system using equivalent energy design procedure

Recently, a high-performance reinforced concrete (RC) frame structure with an energy dissipative cladding panel connection system (EDCPCS) was proposed. It creatively uses the relative deformation between the main structure and the cladding panel through U-shaped steel dampers (USDs) to dissipate plastic energy and control the damage to the RC frame. To realize a performance-based seismic design of this novel structure, performance objectives of the entire structure, USDs, and the frame structure under four earthquake levels were recommended. Subsequently, an equivalent energy design procedure (EEDP) was developed to realize the four-level performance objectives, and a calculation method for the critical design parameters (i.e., energy modification factors) was recommended. To validate the reliability of EEDP, an eight-story structure was designed, and nonlinear time history analyses were conducted under four earthquake levels. The critical seismic responses of the overall structure, energy dissipation characteristics of the USDs, and damage characteristics of the main structure were evaluated. The results indicate that the expected performance was successfully achieved using this method, thus validating the feasibility and reliability of this method. This study provides a practical design method for RC frame structures with EDCPCS.

Comparison of the graph-theoretical force method and displacement method for optimal design of frame structures

In this paper, a graph-theoretical force method is utilized for the analysis of the frame structures to decrease the time required for optimization. The performance and speed of the graph-theoretical force method are compared to those of the displacement method in the optimal design of frame structures. The results indicate that the force method in the considered problems requires less computational time than the displacement method, while both methods have the same accuracy. Additionally, the standard particle swarm optimization algorithm (PSO) is improved to enhance its performance for the optimal design of the steel frames. Benchmark frame examples are studied, and the performance of the graph-theoretical force method and displacement method are compared. The results show that the improved version of the PSO is more robust than the PSO in the optimal design of the steel frames utilizing both methods of analysis.

A procedure for damage-based seismic design of moment frame structures

A new method for seismic design of structures with the aim of controlling earthquake damage to a prescribed level is presented in this paper. The method is specified for special moment frame buildings with vertical and horizontal regularity. The main idea is determining a design story drift in correlation to a selected damage index value. For this purpose, the Park-Ang damage index is correlated with the maximum story drift. Through performing several nonlinear dynamic analyses of selected moment frame steel structures and regression analysis, it is shown that such a correlation is possible for the studied building type by a simple linear relation. Beginning from a desired value of the damage index, the design story drift is calculated using the developed linear equation and the same buildings are designed using a displacement-base procedure. Results of the nonlinear dynamic analysis of the buildings show that the maximum story damage index under a suit of spectrum compatible ground motions is consistent with the selected initial damage index using the proposed procedure.

A novel method for efficient design of frame structures equipped with nonlinear viscous dampers by using computational results of cylindrical friction damper

ABSTRACT In this paper, a new method is presented for designing nonlinear viscous dampers to improve the seismic response of multi-storey frames with braces. In this regard, a 2/3-scale three-storey steel structure is used as a benchmark case. Considering the cylindrical friction damper equipment on the bracings, the optimum slip loads are calculated for cylindrical friction damper of all stories under selected earthquakes records. For three earthquakes in optimised slip loads, the force versus the difference between velocities of two ends of cylindrical friction dampers for all stories is combined and plotted according to the velocity range for all earthquakes. Finally, the velocity–force curve is fitted and used for finding the design parameter of nonlinear viscous dampers. Similarly, the aforementioned steps are applied for El-Centro with three scales (of 50, 100 and 200% El Centro). According to the analysis results, the viscous dampers which are designed by using this approach present better performance than that of cylindrical friction dampers and considerably reduce the structural response. The values of displacement, acceleration and base shear are reduced between 63–96%, 44–85% and 14–78%, respectively. Moreover, the results of viscous dampers designed using three and one earthquakes are very similar.

Optimum Sizing Design of Steel Frame Structures Using Evaporation Rate-Based Water Cycle Algorithm with Greedy Selection

Optimum Sizing Design of Steel Frame Structures Using Evaporation Rate-Based Water Cycle Algorithm with Greedy Selection

Seismic loss optimum design of steel structures using learning‐based charged system search

SummaryOne of the structural engineers' challenges on a regular basis is balancing the expense of initial construction with the cost of future structural loss. At first appearance, employing the optimization method seems to be a viable option. However, since both the structure's analysis and design, as well as the computation of the cost of future loss, are time‐consuming and expensive, combining these processes with the costly optimization progression is prohibitively expensive. The purpose of this study is to present a methodology for the risk‐based optimum design of steel frame structures, as well as to enhance a previously published metaheuristic algorithm for a better optimization approach. The methodology given here allows structural designers to account for seismic risks in the design optimization process without incurring expensive computing expenditures. This approach may be appealing for practical work since it minimizes time‐consuming charges and provides designers with a structural impression. Furthermore, as compared to the standard version, the new optimization algorithm improves performance while decreasing computing costs. Bayesian linear regression is used in conjunction with a parameter identification challenge to derive probabilistic models for estimating structural analysis demand responses. The minimum amount of total initial cost and seismic loss cost is regarded as the objective function of the design of three chosen mid‐ to high‐rise moment frames for the optimization purpose. The results demonstrated enhanced optimization performance as well as a decreased loss cost for employed structures.

Effects of near‐fault acceleration and non‐acceleration pulses on pounding between in‐plan irregular fixed‐base and base‐isolated buildings

Concave surface sliders (CSSs) are considered as an effective solution for retrofitting adjacent buildings irregular in plan that could undergo significant seismic pounding due to torsional displacements. This is because during the sliding phase there is coincidence between the projection of the gravity mass centre of the superstructure and the stiffness centre of the CSSs. However, unexpected torsional pounding, with amplification in a near-fault site, may be induced by variability of friction force and lateral stiffness of the CSSs, depending on the axial load and friction coefficient changes during an earthquake. In this work, structural pounding between fixed-base and base-isolated reinforced concrete (RC) L-shaped buildings, placed adjacent to form T- and C-shaped plans, is investigated. A simulated design of the original fixed-base framed structures is preliminarily carried out in accordance to a former Italian code, for a medium-risk seismic zone and a typical subsoil class. Then, seismic retrofitting with CSSs is carried out, to attain performance levels imposed by the current Italian code in a high-risk seismic zone and for moderately-soft subsoil. A computer code for the pounding analysis between fixed-base and base-isolated test structures is developed, in order to compare effects of nonlinear models of the CSSs that consider constant and variable axial load combined with friction coefficient at breakaway and stick–slip and as function of the sliding velocity, axial pressure and rising temperature at the sliding interface. Attention is focused on the pulse-type nature of near-fault earthquakes generally observed in the velocity time histories but largely overlooked in the acceleration ones. To this end, automated classification algorithms using wavelet analysis are adopted to compile three datasets of seismic input distinguishing between no-pulse and velocity-pulse, the latter further categorised into non-acceleration and acceleration pulses and rotated along the direction most likely to contain strong pulses.

Eco-marathon racing car casing and frame structure design

In addition to the Pneumobil competition, our team will also participate in the Shell Eco-marathon with an electric-powered prototype category car. Based on our results so far, we are in the midfield of European competitions. After several modifications to our current car, we will be building a new car again in 2022. The goal of building eco-marathon racing cars is to achieve the lowest possible energy consumption, and accordingly, great emphasis should be placed on reducing weight and drag coefficient.Our previous cars used a welded aluminum frame and fiberglass. One of the best ways of weight reduction would be a self-supporting, carbon-fiber composite frame structure; however, the team does not currently have the technology to produce this. The frame structure of the new car consists of carbon fiber composite tubes, the nodes are 3D printed, fiber-reinforced composite elements. The streamlined casing of the vehicle consists of vacuum formed PETG elements. By using this structure, the total weight can be radically reduced at minimal cost. In our publication, we describe the main steps in the design of the casing and frame structure, finite element analysis of air resistance and deformations, and the drive chain.

Verification of urban light rail transit (LRT) bogie frame structure design lifetime under variable fatigue loads

The bogie frame is the main structure of the train that supports the train's loads during its operation. These structures are subject to fatigue testing to ensure their design life is up to the required standards. The urban light rail transit (LRT) bogie frame used in the Greater Jakarta area is newly designed and manufactured by a commercial railway rolling stock manufacturer. The design lifetime of this newly designed bogie frame structure under various fatigue load conditions is verified experimentally by fatigue testing. Testing and evaluations were conducted following the EN 13749 standard and VDV recommendation. The fatigue test of the urban LRT bogie frame structure was carried out in the test hall of the BPPT Structural Strength Technology Center (B2TKS) using a combination of seven loadings. The bogie frame was subjected to two variable types of fatigue loads, namely driving in curves and passing points (switches), with 2,000,000 cycles, 4,000,000 cycles, and 6,000,000 cycles of fatigue loadings. The parameter measured on the bogie frame structure is the strain value during the test using a dynamic data logger. The stress values analyzed are the average stress and the stress amplitude and then plotted on the maximum and minimum stress curve. The bogie structure is inspected by the non-destructive test method in all areas of its welded joints. This inspection is carried out before and after the test to ensure whether there are cracks caused by fatigue loads. The results of the fatigue test on the bogie structure under the variable fatigue load conditions show that the maximum stress value of 91.71 MPa at 1,500,000 cycles, that occurs during the test, does not exceed the fatigue limit of the material, and there are no cracks in the structure after the test is carried out for up to 6,000,000 cycles.

Seismic Performance Evaluation Method of Underground Frame Structures Considering the Vertical Seismic Capacity of Structural Components

The seismic performance of large underground structures can be evaluated from two perspectives, namely the horizontal interlaminar deformation and the vertical loading-carrying capacity. The current seismic analysis methods focus on the horizontal seismic performance with the interlaminar drift ratio as the evaluation index. It is difficult to fully reflect the vertical failure characteristics of the overall structure. This paper aims to develop an evaluation method to comprehensively evaluate the seismic performance of underground frame structures. The quantitative evaluation indexes, i.e. the vertical loading-carrying risk factor of columns and the vertical deflection risk factor of slabs, were defined to evaluate the seismic performance of underground frame structures. Then, the seismic performance evaluation method was established and the evaluation processes were described. Seismic response analysis of an underground frame structure with different spans on the upper and lower stories was conducted, and the seismic performance of the structural components and overall structure was quantitatively evaluated by using the proposed evaluation method. The seismic response laws of columns and slabs were analyzed and the potential failure mode of the structure was clarified. Furthermore, the failure mechanism of the structure was explained in detail. Numerical results presented that the proposed evaluation method can effectively identify the seismic-induced weak components and failure modes of underground frame structures, and thus has guiding significance for the seismic design of the underground frame structures.

Discussion on the Application of Frame Structure Design in Architectural Structure Design

Discussion on the Application of Frame Structure Design in Architectural Structure Design

Effect of member grouping and pool size of discrete cross-sections on the optimal design of a large-scale 3D steel frame

This paper examines the effect of member grouping and selected pool size of discrete cross-sections on the optimal design of a large-scale steel frame structure. Member grouping is commonly applied to structural optimization problems to significantly reduce the solution space of candidate designs and improve the efficiency and robustness of the search to achieve near-optimum solutions. At the same time, discrete sets of cross-sectional steel shapes (profile lists) assigned to a particular member group are often limited to a subset of cross-sections to further limit the search space and ensure practicality in the final design. However, for large-scale structural systems (e.g., tall buildings), limiting the number of member groups coupled with the exclusion of lighter cross-sectional shapes may significantly impact the quality of the optimal solution (i.e., weight of the frame). This work presents a case study of a large-scale three-dimensional (3D) steel frame to evaluate the sensitivity of the optimal design to practical combinations of member groups and steel profile lists used in multi-story steel frames. A recently developed metaheuristic search algorithm was applied to the steel frame and independent optimization experiments were performed for 16 unique member grouping and profile list combinations (cases) to quantify their influence on the variability and quality of the optimal design. Results reveal a 33% difference in the optimal (final) weight between member group and profile list combinations producing the smallest and largest solution spaces. Yet, the lightest design (corresponding to the largest solution space) produced a greater number of unique steel shapes and required significantly higher computational cost.

A rotational friction damper-brace for seismic design of resilient framed structures

In the present study, a ductile bracing system is proposed which has a rotational friction damper joint with an eccentricity from the diagonal of the bay. Similar to other seismic energy dissipation devices, the developed system can be used for seismic design of new structures, where other structural elements remain elastic during earthquakes, as well as for seismic retrofit of existing structures. The structural behavior of this system is studied thoroughly using theoretical approaches and a seismic design procedure is provided. The formulations are verified by establishing an analysis model of the system and comparing the theoretical and analytical results. A ductility-based design procedure is provided for structures using this system and an illustrative three-dimensional structure is designed and analyzed in detail using various analysis methods. The results show that the proposed damper-brace system and the design process can be efficiently used in practice.

Theoretical analysis and optimization of frame protection to control shallow slope stability and soil erosion

The frame protection is widely used for highways or railways to prevent the subgrade slope from shallow instability. However, the frame structure's design is empirical, and the theoretical analysis of the soil-structure interaction is scarce at present. By analyzing the critical stability conditions of soil particles of the shallow slope under rainfall infiltration, the paper discusses the shielding effect of the frame structure against erosion, together with the stabilization impact and the bearing behavior of frame protection. Under the unfavorable seepage condition, the equation of anti-erosion safety factor and the shallow stability analysis method, as well as the strength examination method of the frame structure, are established. On this basis, an mathematical optimization model is established, which takes the geometric parameters as decision variables, and anti-erosion stability, shallow stability, and safety of frame structure as constraints, and the minimum masonry quantity and shortest construction axis under unit protection area as objective functions. Finally, a case study involving numerical investigation and validation is implemented based on the mathematical optimization model, and the recommended optimal geometric parameters of the frame structure are given, considering the requirement of structural safety and cost-efficiency. The theoretical method and optimization model proposed in this paper can guide the frame structure's design in practical engineering.

The Latest Technology of Polycrystalline Ferroelectric Composite Materials in the Design of the Shovel Frame Structure of the Vibratory Excavating Shovel of the Harvester

China is a large agricultural country. With the development of industrial production, mechanized harvesting has become an inevitable development trend of agricultural material harvesting. In this paper, based on the latest technology of polycrystalline ferroelectric composite materials in the design of the shovel frame of the harvester’s vibrating excavating shovel, the relevant theories of the polycrystalline ferroelectric composite material and the shovel frame of the harvester’s vibrating excavating shovel are based on the literature. After understanding, the shovel frame structure of the vibrating excavating shovel of the harvester was designed, and the latest technology of polycrystalline ferroelectric composite material was introduced in the design of the shovel frame of the vibrating excavating shovel of the harvester to make the vibration system have better performance. The designed shovel frame structure is tested, and the test results show that the horizontal output force received by the shovel designed in this paper increases with the increase of speed and is minimized at 0.26 m/s. The vertical output force decreases first and then increases with the increase of speed. It is the smallest when the running speed is 0.39 m/s. The horizontal working resistance is always greater than the vertical working resistance, and it can be seen that the design of the shovel frame structure can be realized in actual work.

Optimization of an RC frame structure based on a plastic analysis and direct search of a section database

For the optimum design of RC frame structures, a simplified but effective discrete optimization algorithm is introduced in this paper. To determine the member force to be based on the design procedure, a plastic analysis considering the sequential development of plastic hinges in beams and columns up to the point of collapse is conducted, with the subsequent optimum design then devised via a direct search method. The construction of a database for predetermined discrete RC sections and interconnections of all design variables in an RC section with a single design variable associated with the section identification number makes it possible to adopt the direct search method instead of a sophisticated mathematical approach that includes many complicated descriptive functions pertaining to RC beams and columns. The use of the plastic analysis also reduces the maximum member force through moment redistribution, and the direct search method makes it possible to find a true optimum section regardless of the assumed initial section. The efficiency and applicability of the introduced algorithm are verified through correlation studies for typical frame structures. In particular, given that all design criteria in design codes and practical limitations required when undertaking the actual design are already considered while determining RC sections in the section database, the obtained results can be directly applied to the creation of designs. In advance, the use of the obtained optimum design results as initial sections in the preliminary design stage will greatly reduce the number of design steps for the determination of RC sections.

Investigations on motorbike frame material and comparative analysis using generative design and topology optimization

The frame is one of the most important load-bearing structures of a motorbike. Since various components are mounted on the frame, hence rigorous analysis is required based on different design techniques. Among the different techniques for design, generative design and topology optimization are used in the present work. Generative design is a design exploration process that uses machine learning and cloud computing and generates a large number of designs starting from restricted design data. The generative design domain includes geometric feasibility, manufacturability, and cost analysis, which provides the opportunity to achieve design objectives for optimized models. Topology optimization is a mathematical methodology that re-arranges the material distribution within the design domain, for different loads, boundary conditions, and constraints on functional and optimized models. A comparative study based on the mechanical properties of two different designs of motorbike frames created using generative design and topology optimization is proposed. Both of these processes are aimed towards light-weighting the structural models to maximize the performance of the intended design. The practical use of the generative design and topology optimization methodology is demonstrated using a generic CAD-based design of a trellis frame structure and the generative workspace in Autodesk FUSION 360. Comparative analysis was carried out between the conventional Trellis frame, Generative Frame and Topology Optimized frame structures. Distribution of induced stresses within the frame, nodal displacement and equivalent strain are investigated in the present work. Structural mass is decreased by 26.63% in the case of topology optimization and 34.29 % for generative design.

Uncertainty analysis on progressive collapse of RC frame structures under dynamic column removal scenarios

The progressive collapse of structures often causes serious casualties and property loss. The intrinsic characteristic of progressive collapse is large-scale domino-like structural damage caused by accidental local failure induced by uncertainty factors. Therefore, it is vital to conduct uncertainty analyses on the progressive collapse of reinforced concrete (RC) frame structures under dynamic loads. In this study, to better quantify the progressive collapse resistance of RC frame structures, progressive collapse fragility analyses and sensitivity analyses were conducted at both the component and structural levels, taking into consideration the uncertainties in the structural design parameters, including structural loads, geometries, material properties, etc. At the component level, an energy-based simplified analysis method was proposed for the quick assessment of the progressive collapse vulnerability of RC beam-column substructures. At the structural level, a fragility curve cluster was adopted for evaluating the progressive collapse resistance of RC frame structures. A typical 3-story, 4 × 3 span RC frame structure designed according to Chinese codes was evaluated by the progressive collapse fragility curve cluster. It is found that the failure probability of the RC frame may increase by more than 30% after considering the uncertainty factors. Based on the fragility curve cluster, the robustness and reliability of both the RC frame and its components were quantified. And a safety index is proposed for judging whether a structure/component requires a progressive collapse redesign. Furthermore, the sensitivity analysis results indicate that the load effects, strength of the reinforcement steel, and the reinforcement area in a beam significantly affect the structural progressive collapse resistance. The research outcomes can provide references for quantifying the progressive collapse resistance and improving the progressive collapse design of RC frame structures.