Steel Diagrid Research Articles

AERODYNAMIC HIGH-RISE BUILDING IN STRUCTURAL REVIEW AND DESIGN INTEGRATION

Tall buildings that have aerodynamic characteristics are tall buildings that can respond to wind flow and lateral loads that occur on the upper structure of the building. Obstacles in understanding the structural systems in tall buildings often become obstacles for architecture students so design integration cannot be achieved, especially in tall buildings with aerodynamic shapes. Therefore, it is necessary to analyze how the structural patterns that form aerodynamic buildings can be realized using case studies in Indonesia and abroad. The method used in this research is a literature review and analysis with a review of aerodynamic building designs and structures in three building case studies in Indonesia and abroad. It is hoped that by understanding aerodynamic building structural systems, students will be able to combine creativity with their structural systems. Conversely, understanding the structural system can produce design creativity to create an integration of the design and structural system. From the literature review and analysis, it is found that aerodynamic tall buildings have a structural system obtained from twister-shape processing with a composite structural system and a core system. As well as the diagrid system which usually uses a steel diagrid structure system and a core structure system. The core system is still the main reference because its use is more efficient in terms of costs and work methods.

Evaluation of Steel Diagrid Structural System Under Near-Fault Earthquakes

ABSTRACTThe diagrid structural system has become popular in the construction of high-rise buildings in light of significant advantages over other structural systems. The present study explores the effects of the vertical near-fault earthquake component on the axial forces of diagonal elements in steel diagrid structures. Nonlinear time-history analysis was carried out using 11 near-fault earthquake records. A total of nine three-dimensional models of 12, 18, and 24 stories, each with diagonal angles of 45, 63.4, and 71.5 degrees, were designed and analyzed. Due to the three-dimensional modeling complexities of diagrid structures, a method was developed to transform three-dimensional models into two-dimensional ones. Finally, the scenarios with and without the vertical earthquake component were compared. It was found that the incorporation of the vertical earthquake component into the analysis of diagrid structures substantially influenced the axial forces of diagonal elements. This can affect the design load estimation of diagonal elements as the main components of a diagrid structure.

Optimum Geometry of Steel Diagrid Structural System to Resist Progressive Collapse

Optimum Geometry of Steel Diagrid Structural System to Resist Progressive Collapse

Numerical convergence and error analysis for the truncated iterative generalized stochastic perturbation-based finite element method

The main aim of this work is to present a numerical analysis of convergence and accuracy of the selected generalized perturbation-based schemes in linear and nonlinear problems of solid mechanics. An algorithm for determining the basic probabilistic characteristics has been developed using the iterative generalized stochastic higher-order perturbation method adjacent to symmetrically truncated Gaussian random variables. It has been confirmed that usage of a sufficiently high order of the Truncated Iterative Stochastic Perturbation Technique (TISPT) allows for achieving any desired accuracy in determining up to the fourth-order probabilistic characteristics of static structural response. The semi-analytical probabilistic approach is the reference solution in this study, which is based upon the same composite response functions determined with the use of the Least Squares Method created using specific series of FEM experiments. The entire methodology has been provided for the given extreme value of the coefficient of variation αmax of the input uncertainty source. On the other hand, a selection procedure of the stochastic perturbation method order to achieve 1% numerical accuracy in all up to the fourth-order probabilistic moments has been proposed. Computational experiments include simply supported elastic Euler–Bernoulli beam, a set of steel diagrid structures, nonlinear tension of steel round bar as well as homogenization procedure of some particulate composite.

Classification of the Structural Behavior of Tall Buildings with a Diagrid Structure: A Machine Learning-Based Approach

We study the relationship between the architectural form of tall buildings and their structural response to a conventional seismic load. A series of models are generated by varying the top and bottom plan geometries of the buildings, and a steel diagrid structure is mapped onto their skin. A supervised machine learning approach is then adopted to learn the features of the aforementioned relationship. Six different classifiers, namely k-nearest neighbour, support vector machine, decision tree, ensemble method, discriminant analysis, and naive Bayes, are adopted to this aim, targeting the structural response as the building drift, i.e., the lateral displacement at its top under the considered external excitation. By focusing on the classification of the structural response, it is shown that some classifiers, like, e.g., decision tree, k-nearest neighbour and the ensemble method, can learn well the structural behavior, and can therefore help design teams to select more efficient structural solutions.

Seismic fragility estimates of steel diagrid structure with performance-based tests for high-rise buildings

During seismic performance-based design for building structures, the accuracy of limit states criteria is directly related to its real damage state and retrofitting measures after the earthquake. As a new type of structures, diagrid structure has a special way of bearing force. Firstly, in order to accurately estimate the deformation capacity and energy dissipation mechanism under horizontal loads, four plane specimens of steel diagrid structure are designed and seismic performance-based tests under horizontal quasi-static cyclic load are carried out. Secondly, according to the yield strength and horizontal ultimate deformation capacity of diagrid structure, combined with pushover method, the limit state values of four performance levels of diagrid structure are determined. Finally, the seismic fragility of a diagrid structure for high-rise building is analyzed. The results suggest that the bottom tilted columns have obvious deformation visible to the naked eye before failure, and some failure warnings can be given in advance. It is difficult to realize the “beam hinge” mechanism in diagrid structure, and the cumulative damage of “column hinge” is its main failure mode. The bottom tilted column is the first place where plastic hinge occurs. In addition, the recommended value of inter-story drift ratio for judging the yield of steel diagrid structure is 1/128 by these experimental results, and the recommended value of inter-story drift ratio for collapse resistance is 1/85. Based on these experimental results, the probability of diagrid structure in each performance state can be estimated reasonably and effectively.

Structural Properties of Tall Diagrid Buildings Using a Neural Dynamic Model for Design Optimization

The development of structural systems is a constantly evolving process to guarantee safety and serviceability against natural hazards. As a result, diagrid structural systems became a current trend in tubular mid- and high-rise building structures for their significant lateral stiffness and aesthetic potential. Their unique geometric configuration allows the efficient distribution of internal forces that lead to optimal structural designs. However, existing design codes and provisions do not provide specific guidelines for their design under earthquake and wind loading. For this reason, this paper studies the properties of steel diagrid structures, including optimal diagrid angle, diagrid density, and fundamental period, as a function of geometric parameters. This study uses a large set of structural models with aspect ratios (H/B) from 1 to 4, diagrid angles (θ) between 45° and 90°, and diagrid densities (ρd) between 3 and 12. The structural design of each model is obtained using a soft-computing optimization algorithm, denominated hybrid counter propagation neural dynamic (CPND) model, that determines member sizes from a database of commercially available W-shapes following ASCE 7-16 standard and AISC-15 steel construction manual. This investigation confirms that the optimal diagrid angle increases with height, highlights the importance of diagrid density in structural design, and demonstrates the effect of the diagrid angle on the fundamental period. A new set of equations are proposed for: (1) the optimal diagrid angle as a function of height, and (2) the fundamental period of diagrid structures as a function of angle and height. The proposed equations allow the estimation of structural properties for the design of steel diagrid structures.

On Selecting Composite Functions Based on Polynomials for Responses Describing Extreme Magnitudes of Structures

The main aim of this work was to investigate a numerical error in determining limit state functions, which describe the extreme magnitudes of steel structures with respect to random variables. It was assisted here by the global version of the response function method (RFM). Various approximations of trial points generated on the basis of several hundred selected reference composite functions based on polynomials were analyzed. The final goal was to find some criterion—between approximation and input data—for the selection of the response function leading to relative a posteriori errors less than 1%. Unlike the classical problem of curve fitting, the accuracy of the final values of probabilistic moments was verified here as they can be used in further reliability calculations. The use of the criterion and the associated way of selecting the response function was demonstrated on the example of steel diagrid grillages. It resulted in quite high correctness in comparison with extended FEM tests.

Appropriate intensity measures for probabilistic seismic demand estimation of steel diagrid systems

Performance-based earthquake engineering (PBEE) predicts the performance of structures subjected to earthquake ground motions to improve seismic risk mitigation decisions. In PBEE, intensity measures (IMs) are employed as a link between earthquake hazard and seismic response. To the best of the authors' knowledge, investigation of the appropriate IMs for the probabilistic seismic demand evaluation of steel diagrid systems has not been presented in literature so far. In this study, the efficiency, practicality, proficiency, sufficiency, and scaling robustness of 38 candidate IMs for estimating the seismic response of low- to high-rise steel diagrid systems are investigated. Finite-element models of the structures are performed in OpenSees software and subjected to incremental dynamic analysis (IDA) using 22 far-field earthquake records. The whole response of the investigated diagrid systems is captured in terms of maximum inter-story drift ratio (MIDR). The appropriate IMs among the candidate IMs for steel diagrid systems are identified utilizing the concepts of efficiency, practicality, proficiency, sufficiency, and scaling robustness. The regression analysis results showed that peak ground velocity (PGV) and the ratio of PGV to peak ground acceleration (i.e., PGV/PGA) are the most appropriate IMs for seismic response prediction of steel diagrid systems under far-field ground motions. Furthermore, the collapse fragility curves, as well as drift hazard curves, were obtained based on various IMs. It was observed that the proposed IMs reduce the uncertainty in fragility curves. Also, it was concluded that seismic IM has a significant impact on the structural response hazard of steel diagrid systems.

Mechanical characteristics and deformation calculation of steel diagrid structures in high-rise buildings

In order to propose a simple and practical methodology for calculating the deformation of diagrid structure with polygon plane in arbitrary direction, the diagrid structure is considered to be mainly composed of “element” by geometric method. The vertical stiffness and lateral stiffness of diagrid structure with arbitrary polygon plane under vertical load and horizontal load are derived respectively. The corresponding laboratory test and numerical simulation analysis are carried out through the scale models of steel diagrid structures. The analysis results show that the calculated results of each deformation equation are in good agreement with the test results and numerical simulation results. In addition, the influence of the parameters on the stiffness of the structure is revealed theoretically. The results demonstrate that when the diagonal angle is about 55°, the variation of the diagonal angle has the greatest effect on the vertical stiffness of the diagrid structure. Moreover, the vertical stiffness of steel diagrid structure is smaller than that of traditional structure, and the vertical displacement is obviously larger. It is necessary to limit the inter-story drift ratio of vertical modules. Furthermore, current paper theoretically explains that the more edges of diagrid structure, the greater the horizontal shear stiffness of the structure.

Localized health monitoring for seismic resilience quantification and safety evaluation of smart structures

Natural hazards such as earthquakes, hurricanes, and floods cause billions of dollars of economic loss and claim thousands of lives every year. Researchers have proposed various tools and techniques to evaluate, manage, and mitigate seismic risk and improve resilience. Nonetheless, given the uncertainties involved, accurate system assessment requires real-time data on structural health and performance which can be attained through structural health monitoring (SHM) systems. This paper integrates component-based resilience quantification methods and SHM techniques to present a new probabilistic framework for seismic structural system evaluation and decision analysis. A trilateral framework is introduced which (1) uses the data obtained from a localized wireless sensor network to detect and locate damage, (2) develops component-based functionality curves to quantify the seismic resilience of the structure, and (3) makes post-quake rapid decisions based on a multi-criteria safety evaluation method. A nonlinear autoregressive exogenous (ARX) model is used to identify structural response and a statistical damage-sensitive coefficient is used to detect, locate, and measure damage in the system. Minor damages due to corrosion and major damages due to past extreme events are studied in the functionality analysis. Two groups of archetype building structures located in a high seismic region are studied, namely steel diagrid and special reinforced concrete structures. The results show that maximum absolute floor acceleration is the most accurate demand parameter for locating damage whereas maximum floor displacement and interstory drift ratio can effectively detect and measure damages.

Seismic analysis of tall concrete and steel diagrid structure using response spectrum and time history method in e-tabs

In the recent years due to lack of land the construction of high rise buildings widely increases and these buildings are affected by lateral loads due to wind or earthquake. To resist these horizontal loads lots of construction methods are available. Herein system peripheral columns of the building are eliminated.To resist the seismic forces we arrange the diagonal columns. In this study seismic performance of 20-story concrete and steel diagrid structures are assessed using response spectrum method. Only for concrete diagrid structure using time history method. The present work is made for studying the response and time period with acceleration of high rise building with concrete and steel diagrid structural system. To this aim response of two different diagrid structures of G+20 storey are carried out to obtain optimized position of diagrid. E-Tabs software mainly focus on seismic analysis of response spectrum and time history method. As per IS456:2000 and IS800:2007 all structural members of diagrid model are designed and IS1893:2002 and ASCE7-10 is considered for seismic analysis for concrete and steel diagrid structure. An evaluation of constraints storey shear, storey drift, storey displacement, Time period and Structural weight is done to determine the efficient and cost effective structure. The analysis of the building is carried out by using ETABS software.

A Preliminary Reduced Three Dimensional Model of Regular Diagrid Tall Buildings for Fast Seismic Analysis. (Dept. C)

This paper introduces a reduced 3D diagrid model to save both time and computer memory for modeling and seismic analysis. The analysis of different models of steel diagrid tall buildings with variable heights and inclinations of diagrid is performed applying a finite element program SAP2000. Three clusters of diagrid buildings with different aspect ratios (height-to-width) and reliable optimum inclination angles are examined. The cross sections for diagrid elements are designed using stiffness -based design method which is more reliable for diagrid buildings. The 3D finite element model as a real structure and the proposed reduced seismic model that reducing finite element model up to twenty percent by canceling a specified number of floors with restrictions in modeling are employed. Equivalent lateral Force, dynamic response spectrum, and linear time history analyses are considered. A comparison of obtained results in terms of lateral displacement at top of the building, first mode period of vibration and base shear are presented. The conclusions reveal that the proposed reduced 3D model is convince for preliminary modeling and analysis of regular diagrid buildings in existence of seismic loads.

Computational design and manufacturing of a half-scaled 3D-printed stainless steel diagrid column

The manufacturing of large scale structures with Additive Manufacturing (AM) represents one of the main challenges facing the construction industry today. The first recent large-scale realizations with the Wire-And-Arc Additive Manufacturing (WAAM) technology have shown the potential of WAAM in changing the way steel structures are currently designed and manufactured. However, despite these pioneering applications, the full comprehension of synergies and possibilities of WAAM in terms of architectural shapes, structural behavior and material response are far from being completely exploited.In this article, the overarching design process from concept to fabrication of a half-scaled diagrid column 3D printed with WAAM technology is illustrated. The research methodology is based on a computational workflow integrating various aspects such as material properties, manufacturing features and global architectural design. The final designed WAAM-produced diagrid column has been exposed at “The Big 5 - International Building and Construction” show, held in Dubai from November 25th till November 28th 2018.

Evaluation of the seismic performance factors for steel diagrid structural systems using FEMA P-695 and ATC-19 procedures

The diagrid structural systems are mainly used for their structural capabilities and architectural aesthetic possibilities which are provided by the unique geometric configurations of these systems. However, the seismic performance factors of these structural systems are not yet explicitly recommended in the existing building codes. In this study, the seismic performance factors (SPFs) of 6- to 24-story steel diagrid structures are determined considering the post-buckling behavior of diagonal members in compression. Also, the effect of change in span length and the diagonal angles on the SPFs of diagrid structures is studied. The ATC-19 coefficient method is used for calculating the SPFs while FEMA P-695 approach is adopted for evaluating the accuracy of the computed factors. Also, the seismic collapse capacity of these structures considering uncertainties in ground motion, modeling, design, and test data is evaluated based on the FEMA P-695 methodology. The OpenSees software is used for modeling and performing the numerical analyses. The obtained results indicate that by increasing the height of diagrid structures, the over-strength, the response modification factor and the median collapse intensity decrease while the ductility factor increases. It is also concluded that the adjusted collapse margin ratios of the diagrid archetypes are larger than the limits suggested by FEMA P-695.

Seismic reliability analysis and estimation of multilevel response modification factor for steel diagrid structural systems

Diagrid systems are emerging as one of the structurally efficient and architecturally aesthetic solutions for tall buildings. Despite the fact that such systems are increasingly used in modern construction, current literature lacks detailed information regarding their structural behaviour and seismic design parameters to ensure satisfactory performance under different earthquake intensity levels. This study aims to assess the seismic reliability of diagrid structural systems and develop more efficient performance-based design methodologies. Demand and supply response modification factors are calculated for 16, 24 and 32-storey buildings with diagrid structural systems using 65° diagrid angle and designed in compliance with current standards under a set of 12 spectrum compatible earthquakes. The results are then used to develop a novel multi-level response modification factor (R-Factor) for diagrid structural systems as a function of site seismicity and acceptable damage level. Subsequently, comprehensive seismic reliability analyses are conducted to assess the seismic performance of the selected structures under intensity levels corresponding to DBE and MCE hazard levels (earthquake scenarios with return periods of 475 and 2475 years, respectively). In general, results of this study demonstrate acceptable seismic performance and reliability of steel diagrid systems. It is shown that even using an R-Factor equal to 4 in the seismic design process could ensure that diagrid structures remain in a performance level higher than Life Safety (LS) for both DBE and MCE hazard levels. Multi-level response modification factors proposed in this study can be directly used in performance-based design of diagrid structures to satisfy different performance targets under any seismic hazard level.

Comparison of Static Pushover Analysis and IDA-Based Probabilistic Methods in Assessing the Seismic Performance Factors of Diagrid Structures

This study attempts to reliably quantify the seismic response parameters of the steel diagrid structural systems. In that regard, in addition to the conventional static pushover analysis (SPA), the dynamic pushover analysis (DPA) based on the incremental dynamic analysis (IDA) technique is also considered. FEMA P-695 recommends a methodology for establishing seismic performance factors (SPFs). The present study tries to propose a simpler framework for estimating and validating SPFs while applying the concepts of FEMA P-695 guideline. The results show that the R-factors obtained with the SPA procedure for steel diagrid systems are conservative and the IDA-based probabilistic method gives a more rational value for the R coefficient. Furthermore, the proposed simplified method has good agreement with FEMA P-695 in predicting the collapse capacity of diagrid models.

Evaluation of Seismic Performance of Double-layer Steel Diagrid Systems

A new type of structural systems, called diagrid, has been introduced in recent years, in which the diagonal members are often located in the exterior frames while the interior frames, including vertical columns, resist only the gravity loads. A novel double-layer diagrid system is proposed in this study and the equations related to its lateral stiffness are extracted. The combination of angles of internal and external diagonals is also investigated to obtain the desired stiffness. Eventually, considering a 12-story structural model, the seismic performance of the proposed system is investigated and compared with conventional diagrid systems through changing the angle of diagonals in interior and exterior frames. Results show that double-layer diagrid systems are more suitable than conventional diagrid systems in providing stiffness and strength criteria. Moreover, a proper combination of internal and external angles improves the ductility, as well as increasing the amount of energy dissipated by the structure.

Multi-criteria decision-making for seismic resilience and sustainability assessment of diagrid buildings

Resilience and sustainability are both key criteria in risk-informed decision analysis of structural systems. However, a comprehensive framework which incorporates both in a multi-criteria decision-making (MCDM) process is yet to be developed particularly for more recent structural systems such as diagrids. This paper introduces a coupled resilience- and sustainability-based decision-making framework for seismic design and rehabilitation of building structures. FEMA method for intensity-based and time-based loss, downtime, and casualty estimation are used to evaluate seismic asset, time, and life losses. Economic input-output life-cycle assessment method is adapted to evaluate the environmental loss due to earthquakes, as well. Aiming to study the trade-off between various economic, social, and environmental impacts of earthquakes, an MCDM framework is proposed based on analytic hierarchy process, multi-attribute utility theory, and technique for order preference by similarity to ideal solution (TOPSIS). The framework is used to study the resiliency and sustainability of archetype steel diagrid buildings in a high seismic region. Six scenarios with different objectives including minimum asset, time, life, or environmental loss and maximum resilience are studied. A survey is conducted to find the weight factors for each criterion for each scenario. Results show that in an MCDM framework, the benefits of sustainable design techniques can outweigh possible shortcomings due to structural configuration and performance.

Seismic performance evaluation of high-rise steel buildings dependent on wind exposures

The lateral load-resisting system of high-rise buildings in regions of low and moderate seismicity and strong wind such as the typhoon in the Korean peninsula considers the wind load as the governed lateral force so that the practical structural engineer tends to skip the evaluation against the seismic load. This study is to investigate wind-designed steel diagrid buildings located in these regions and check the possibility of the elastic design of them out. To this end, first, the diagrid high-rise buildings were designed to satisfy the wind serviceability criteria specified in KBC 2016. Then, the response spectrum analyses were performed under various slenderness ratio and wind exposures. The analyses demonstrated the good seismic performance of these wind-designed diagrid high-rise buildings because of the significant over-strength induced by the lateral load-resisting system of high-rise buildings. Also, the analysis results showed that the elastic seismic design process of some diagrid high-rise buildings may be accepted based on slenderness ratios in all wind exposures.