Conventional Structural Systems Research Articles

Topology optimization of multi-material active structures to reduce energy consumption and carbon footprint

A multi-material active structure is a mechanical system made of passive and active materials with the ability to alter its configuration, form, or properties in response to changes in the environment. Active structures have been investigated to design lightweight structures and structures with the ability to “smartly” alter their shapes and/or internal forces. Recently, the potential of active structures to reduce environmental impact, i.e., reduce energy consumption and greenhouse gas (GHG) emissions, has been investigated. It has been verified that, compared to passive structures, active structures can not only use less material but also consume less energy and cause less GHG emissions during their service life, and thus have a significant potential to be applied as environment-friendly mechanical structures. This study aims to develop a general topology optimization (TO) approach to design novel multi-material active structural systems to reduce environmental impact. The approach is based on the density-based TO scheme. Passive and active materials are considered in the TO process and are required to be optimally distributed according to the optimization objective and constraints. The energy consumption or GHG emissions caused by the structure during its service life are treated as the objective function to be minimized under multiple displacement requirements. Typical examples are carried out to verify the developed approach. Results show that the topology optimized active structures may not only achieve significant weight savings but also less energy consumption and GHG emissions compared to equivalent topology optimized passive structures, which indicates that the developed approach has the potential to be applied to design novel structural systems with lighter weight, larger span, and with less environmental impact compared to conventional passive structural systems.

Analytical Behavior of Conventional and Virtual Outrigger Structural Systems by Using Modal Pushover Analysis

Analytical Behavior of Conventional and Virtual Outrigger Structural Systems by Using Modal Pushover Analysis

Automated minimum-weight sizing design framework for tall self-standing modular buildings subjected to multiple performance constraints under static and dynamic wind loads

In recent decades, the shortage of affordable housing has become an endemic issue in many cities worldwide due to the ongoing urban population growth. Against this backdrop, volumetric steel modular building systems (MBSs) are becoming an increasingly compelling solution to the above challenge owing to their rapid construction speed and reduced upfront costs. Notwithstanding their success in low- to mid-rise projects, these assembled structures generally rely on a separate lateral load-resisting system (LLRS) for lateral stiffness and resistance to increased wind loads as the building altitude increases. However, additional LLRSs require on-site construction, thereby compromising the productivity boost offered by the MBSs. To this end, this paper proposes a novel optimisation-driven sizing design framework for tall self-standing modular buildings subjected to concurrent drift, floor acceleration, and member strength constraints under static and dynamic wind loads. A computationally efficient solution strategy is devised to facilitate a meaningful sizing solution by decomposing the constrained discrete sizing problem into a convex serviceability limit stage (SLS) and a non-convex ultimate limit stage (ULS), which can be then solved using preferred local and global optimisation methods, separately. The framework is implemented by integrating SAP2000 (for structural analysis) and MATLAB (for optimisation) through SAP2000′s open Application Programming Interface (API), and demonstrated using a 15-storey self-standing steel modular building exposed to three different levels of wind intensity. A comprehensive performance assessment is conducted on the optimally designed case-study building to investigate its elastic instability behaviour, geometric nonlinear effects on wind-induced response, and impacts of global sway imperfections on member utilisation ratios under wind effects. It is concluded that tall self-standing modular buildings can be achieved economically using ordinary corner-supported modules without ad hoc structural provisions, while consuming steel at similar rates to conventional building structural systems. Furthermore, the proposed sizing framework and solution strategy have proven to be useful design tools for reconciling the structural resilience and material efficiency in wind-sensitive self-standing modular buildings.

Development of Innovative Lateral Resistance Systems Featuring Earthquake-Protective Dampers

Several conventional structural systems require sufficient retrofitting design procedures, improvements, and reconstructions to withstand lateral loads and to decrease the occurrence of damage. High strength capacity and ductility for seismic lateral resisting systems improve the structural vulnerabilities and limit damage concentrations in areas subject to seismic conditions. Several types and shapes of structural systems with appropriate ductility and energy dissipation features are currently established as structural fuses to enhance the general performance of the structures and decrease seismic ramifications. To enhance the energy dissipation performance and concentration of the inelasticity, improving the ductile behavior and limiting the unpredictable accumulation of plastic strains is essential. The conventional eccentrically braced systems are examined and reestablished, and the effects of shear fuses used in high-rise buildings are investigated for prototype buildings by implementing the verified simulations. Next, seismic protective fuse systems with innovative dampers consisting of several butterfly-shaped shear links are established. Ultimately, the design guidelines are established based on the conventional eccentrically braced frames (EBFs), which are redesigned with the use of noble seismic protective fuses, and the hysteretic behavior is obtained and compared accordingly.

Analytical Evaluation of Most Effective Diagrid Angle Considering Severe Earthquake Time Histories

High rise structures and their structural mechanisms are evolving rapidly due to an exponential growth of urbanization. Few conventional structural systems have been efficient in withstanding heavy wind gusts as well as earthquakes. A newcomer in the list of sustainable high-rise structures is the Diagrid. A diagonal grid or Diagrid structure is a framework of diagonally intersecting inclined column sections. Due to higher resilience and robustness, the trend is rapidly shifting towards Diagrid. Diagrid structures are adopted as they take into account a number of factors like structural stability, aesthetic appearance and economic considerations. The triangulated formation of columns and ring beams transform all the external forces into direct axial forces. The effectiveness of the diagrid mechanism depends on the angle of the diagrid. In this project, analysis of symmetric diagrid building, with various diagrid angles has been carried out using software SAP2000. The analysis results for top storey displacement, base shear and modal frequency are considered for evaluating the optimal range of diagrid angle considering earthquake time histories.

Seismic design and assessment for midrise buildings equipped with damped‐outrigger system

SummaryThe damped‐outrigger system has been proposed to improve the performance of conventional outrigger systems in controlling the structural seismic response by increasing the damping and stiffness. The purpose of this study is to demonstrate the effectiveness of using damped‐outrigger systems in midrise buildings and provide engineers with a comparison between conventional structural systems such as moment resisting frame (MRF) and buckling‐restrained braced frame (BRBF) in proposing the most suitable structural system. In this study, the buckling‐restrained brace and viscous damper are adopted as the energy dissipation devices in the damped‐outrigger system. A total of 48 midrise numerical models with various building heights and structural systems are analyzed using nonlinear response history analysis and incremental dynamic analyses. The analysis results show that the midrise buildings equipped with a damped‐outrigger system with either viscous damper or buckling‐restrained brace (BRB) can reach similar and even better seismic performance when compared with the BRBF; it also reduces the structural responses by around 30% for the maximum roof drift and acceleration responses when compared with MRF. The analysis results could provide a reference for structural engineers when selecting suitable lateral force resisting systems for midrise buildings.

Low-Cost Housing Using Monolithic Dome and Cylindrical Structure

Abstract: Dome is an element similar to the hollow half of a sphere. It can also be defined as a thin shell generated by the revolution of a regular curve about one of its axes. The type of the curve and the direction of the axis of revolution determines the shape of the dome. Monolithic dome structures are cast in a one-piece form. The paper aims to do a comprehensive study of Monolithic Domes and the various advantages and key aspects of these structures and to determine whether they are more energy efficient, eco-friendly, cost effective and durable housing options compared to conventional structural systems. Keywords: Low Cost Housing, Monolithic Domes, Cylindrical Structures, Structural analysis, paper review

Seismic performance evaluation of glulam structures with either braced frames or knee-braced frames as the main lateral load resisting system

The glulam knee-braced frames and braced frames are both conventional structural systems that are generally adopted in engineering practice. However, it remains a question what are the advantages and challenges of the knee-braced frames compared with the braced frames and how to choose the appropriate lateral-resisting structures for the projects under a given design requirements. This paper provides numerical models of 3- story, 5- story, 6- story and 9- story glulam braced frames and glulam knee-braced frames with the same architectural plan view. Increment dynamic analysis (IDA) is performed to determine the limit state of MaxISDR (maximum inter-story drift ratio) for the glulam braced frames and the glulam knee-braced frames under different seismic hazard levels, i.e., IO (Immediate Occupancy), LS (Life Safety), CP (Collapse Prevention) and CD (Complete Destroy). Fifty earthquake records are adopted for the subsequent probabilistic seismic demand analysis based on the MaxISDR and ResISDR (residual inter-story drift ratio) damage indices. The fragility curves of these two types of structures are highlighted. The results show that, the limit state of MaxISDR for the glulam braced frames under the IO, LS, CP and CD hazard level are recommended to be 0.6%, 1.2%, 2.0% and 3.5% respectively. The limit state of MaxISDR for the glulam knee-braced frames under the IO, LS, CP and CD hazard levels are recommended to be 1.0%, 2.0%, 3.2% and 5.5% respectively. In addition, for the structural height that below 6 stories, the knee-braced frames have lower probability of MaxISDR exceedance than the braced frames under the earthquake with high PGA and lower probability of ResISDR exceedance than the braced frames. However, for the structural height of 9-stories, the recoverability of the knee-braced frames decreases rapidly. Adding some braces to the knee-braced frames can be a good solution to increase the lateral stiffness of the structures. The comparison results may provide technical reference for the structural design of glulam structures.

Montažne aluminijske hale

Prefabricated aluminium halls are usually temporary structures with multiple uses. Their biggest advantage is low weight resulting in lower transport costs and allowing for quick assembly. Today, there is a growing demand for aluminium halls to become permanent structures, and therefore, in meeting the requirements of EN 199x norm series, it is necessary to optimize the calculation aspect of conventional structural systems with reinforced bolted joints. An overview of the most common structural systems, typical aluminium profiles and joints with steel reinforcements, as well as a common approach for design and assembly, is presented in the paper.

Evaluating the ductility reduction factors of SDOF self-centering earthquake-resisting structural systems

In the past two decades, considerable research works have been directed toward the development of self-centering (SC) earthquake resisting structural systems that are able to make structures usable and repairable after strong ground motions. The focus of these research works is on eliminating the residual deformations and on preventing the earthquake damage in the primary structural components. In comparison with conventional structural systems, the hysteretic responses of SC structural systems are characterized by high levels of post gap-opening stiffness and with low levels of energy dissipation. This indicates that self-centering structural systems may have spectral response characteristics different from those of conventional systems. In this study, the ductility reduction factor (Rμ) which is required for the estimation of the strength demands is evaluated for SC single degree of freedom systems. The results obtained indicate that SC systems generally have Rμ levels lower than those of conventional systems. Modification factors that can be used to relate the Rμ levels of SC systems to those of conventional structural systems are introduced in this study and found capable of accurately predicting the Rμ levels of SC systems.

Equivalent viscous damping for linked column steel frame structures

Linked column steel frame system (LCF) is a new lateral-gravity resisting system aimed at reducing the time and costs of repairs after a seismic event. The performance objectives of this system are highly dependent on the deformations and the sequences at which fuses are formed in the structure. Therefore, in order to meet the performance objectives of this system, using a performance-based design method (e.g. the direct displacement-based design (DDBD) method), that directly controls the structural response would be useful. In the DDBD method, the equivalent viscous damping (EVD) is an important parameter which represents the energy dissipation of a structure due to its nonlinear (hysteretic) behavior. In the literature, there are some EVD expressions for conventional structural systems; however, no expression has been given for the LCF system, yet. The purpose of this study is to develop some reliable EVD expressions for the LCF systems by investigating the nonlinear behavior of 20 single-story frame samples of different configurations with variable link beam lengths. To this end, the EVD of the frames was calculated based on their hysteretic response loops under cyclic loading. Furthermore, the EVD values was calibrated using the inelastic time-history dynamic analysis of the frames under 10 spectrum-compatible earthquake records to propose some new EVD expressions for the LCF systems with short and long link beams. The results indicate that the EVD expressions available in the literature are very conservative for the LCF systems with short link beams.

Modelling and design analysis of light gauge steel systems against conventional structural systems

The paper tries to focus on the importance and necessity to adopt new advanced construction techniques to attain fast and sustainable development in construction industry. Concrete frame construction and hot rolled steel erection are regular conventional methods which are time consuming, requires heavy manpower, machinery, and high fabrication cost. Recent developments in the field are focused to attain ecofriendly sustainable and economical construction. LGS (Light gauge steel) system is one of those which is a dry construction and can be carried out in remote locations with greater feasibilities. LGS system is a construction technology which uses cold formed steel as the construction material, is formed by compressing the steel at very cold temperatures and are made to thickness varying from 0.5 − 3 mm. The paper tries to analyze, design for the structural stability, compares the time and cost effectiveness of LGS system to conventional systems. Vertex Bd is used for modelling, STRAP 2018 for analysis of Light gauge steel sections, Staad pro is used for modeling, analysis, and design of conventional Structures. The studies signify that LGS system proves to be a better solution for mid-rise structures and best suitable option for construction at remote locations.

Study and Comparison of Seismic Behaviour of Isolator-Damper Hybrid Control System with Conventional Structural Systems

In this paper, in addition to introduce a hybrid structural system contained local isolators and dampers, its behavior and functional capabilities were studied on a conventional structure. For this purpose, an RC frame building with six-story was designed based on valid codes and then, in four cases based on the number of spans, it was split into two separate adjacent frames. Base isolation was done underneath the columns of one frame, while the bottom connections of the other frame’s columns were remained fixed and viscous dampers provided the connection of two adjacent frames on the same floors. Nonlinear time history analysis (NTHA) under three near-fault and three far-fault earthquakes and frequency-domain analysis are performed. Displacement, drift, acceleration and shear forces of the stories in the four proposed hybrid cases with two limited cases, full base-isolated and full base-fixed frames, as well as nonlinear hysteresis behavior of a damper and an isolator are assessed. The results showed that using the novel hybrid control method in most cases can mitigate deteriorating effects of all types of seismic motions observed in the conventional structural systems. However, among them, two cases (2 isolated columns -5 fixed columns and 3 isolated columns -4 fixed columns) had the best significant influence on seismic performance and structural response reduction. Furthermore, frequency response functions of displacement and acceleration with respect to ground acceleration demonstrated that the two proposed cases further suppress the responses of the limited cases, over a wide range of frequencies including all natural frequencies. Due to decrease about 50-70% in the number of base isolators (compared to full isolation) lead to considerable construction cost savings. In spite of the limitation of ASCE7-10 code on separately using base isolators and dampers on structure, applying the proposed combination technique of these two dissipating devices can overcome the limitation.

Proposed design procedure for steel self-centring tension-only braces with resilient connections

While conventional steel seismic resistant structural systems may provide sufficient safety for the occupants, generally they depend on damage in the selected structural members to resist severe earthquakes. Therefore, after such an event, there may be considerable economic loss and significant repairs followed by business downtime. In addition, the post-event residual displacement of the structure can compromise the post-disaster functionality of the building. Recent severe earthquakes in New Zealand have highlighted the problems with assessment and repair or replacement of buildings designed for controlled damage and have provided a strong motivation for researchers and engineers to start developing concepts and design methods for low damage self-centring systems.This paper proposes a step-by-step design procedure for steel braced frames with diagonal tension-only braces equipped with the innovative Resilient Slip Friction Joint (RSFJ) connections. The proposed procedure is used to design a 5-story steel structure with RSFJ tension-only x-braces to verify its efficiency and to demonstrate that the system can meet the ductility demand recommended by the standard. The numerical results showed that the proposed procedure could accurately predict the behaviour of the system and potentially can be used for low damage bracing systems with a flag-shaped load-deformation response.

Stability control of a novel frame integrated with an SMA-MRF control system for marine structural applications based on the frequency analysis

Structural integrity and ensuring the stability of steel frame structures, including marine and coastal structures, are the main challenges for designers in civil infrastructures, particularly in oil platforms, subjected to tough periodic and non-periodic environmental loading conditions. Variable loadings with different amplitudes and frequencies may lead to the stability of steel structures loss. In order to keep the stability of the steel structures and prevent possible damages, reliable yet efficient structural control systems are in demand. Conventional structural control systems need significant activation energy and/or in-depth users knowledge to be effective. Most recently, smart materials and systems, notably shape memory alloy (SMA) and magnetorheological fluid (MRF), are considered to replace with the conventional systems. In this study, the SMA-MRF based structural control systems are installed in a simplified marine structure to investigate the frequency responses of the structure subjected to three scaled ground motions. Three structural parameters including the root-mean-square (RMS), the peak displacement, and particularly the frequency analysis are studied. The results show remarkable enhancement in structural behavior equipped with the SMA-MRF based system.

Evaluation of Structural Systems for Industrial Dairy Farming Facilities

This paper presents the assessment of conventional structural systems used for industrial dairy farming focusing on the cost and energy consumption. Various structural forms for industrial dairy farming were investigated considering dozen of structural models and materials. Eleven different structural systems were compared in terms of cost and energy consumption. Steel girders, steel columns, glued-laminated timber, reinforced concrete (RC) columns and steel trusses were used in this research as the structural components and materials. The SAP2000 software was used for the analysis of the modeled structures. The obtained results of the analyses demonstrated that the use of RC members or prefabricated concrete components is economically advantageous, while the use of glued-laminated timber was the least economical alternative. The highest cost was observed for a structural model fabricated with a conventional Gable steel frame and the lowest cost was observed for a structural model made of a 2-span twin mono-pitch Portal frames constructed with prefabricated RC beams and columns. However, the lowest energy consumption was observed for a structural model constructed with a single-span twin mono-pitch Portal frames constructed with RC columns and glued-laminated timber beams and the highest energy consumption was observed for the structural model fabricated with a conventional Gable steel frame, which had the highest cost.

BIM Data Exchange Standard for Hydro-Supported Structures

With the rapid adoption of building information modeling (BIM) across diverse industries, the need for a universal standard for BIM data exchanges has become critical for the success of BIM applications. Questions of the level of development and interoperability of BIM as methods to exchange data and integrate various model-based applications into an efficient work process have come to the forefront of BIM standardization to improve the design and construction of facilities. Current BIM software authoring tools center on conventional structural systems and are not yet adequate for modeling floating structures. Hydro-supported structures comprise a special type of structure that relies primarily on the hydraulic buoyancy of the supporting water body to maintain equilibrium and safety. It is an area that is increasingly drawing the attention of architects and engineers to resolve many issues in coastal areas and to deal with issues related to increased flooding and tropical storms, such as shoreline stabilization, hurricane response, alternative energy, and rainwater collection and utilization. The study centers on expanding BIM standardization for designing and analyzing floating and amphibious structures. It seeks to address the information delivery manual (IDM) and model view definitions (MVDs) as they provide the basis for data exchange specifications for the industry foundation classes (IFC) schema. This research aims to enable a proficient BIM workflow for designing hydro-supported structures characterized by the coherent, organized, and reproducible exchange of consistent data that is commonly recognized across the architecture, engineering, and construction (AEC) industry.

The role of multi-story structural building systems on reducing embodied energy consumption and carbon emissions

During the last decades many structural building systems were implemented in multi-story buildings production. Each of these systems consumes energy and produce carbon emissions from the early stage from the extraction of materials to the construction of a building. The selection of structural building systems with low embodied energy and carbon emissions reduces the impact of buildings on the global environment. The purpose of this research is to make a comparison in embodied energy consumption and carbon emissions between the most conventional building structural systems for multi-story building in Iraq. Through examine different solutions for structural building systems. This research aims to identify the most efficient structural building systems and materials in embodied energy consumption and carbon emissions for multi-story buildings in Iraq. Results demonstrated that the building of reinforced concrete structure has provided better results and consumed less embodied the energy and carbon emissions, as compared to the pre-cast concrete and steel structural building systems.

Assessment of the Dynamic Temperature Profile in Fire Loaded Sandwich Structures Based on Wood in Comparison with Conventional Structural Systems

Fire safety is an important feature of healthy internal environment. If a fire breaks out, the interior of fire compartments within the building is exposed to very high temperatures and further phenomena accompanying the burning process. All of them impact the boundaries of the compartment structures, including the structures that are located inside them. Some structures serve the load bearing function hand in hand with fire barriers, some are only fire barriers. As to the dramatic increase of temperature, its impact upon the opposite surface of the fire separating structure should be considered, in particular regarding the behavior of the load bearing elements and their stability. This is topical at the present day, since the conventional construction materials are seen to give way to wooden sandwich structures that are preferred especially for their thermal insulation properties, low weight, small thickness and speediness of construction. The article uses dynamic simulation to illustrate how these modern structures react to high temperatures within specific time intervals, offering comparisons with traditional brick structures.

A Comparative Study on the Structural Analysis of Diagrid Structural Systems with Conventional Structural Systems for different Plan Configurations

A Comparative Study on the Structural Analysis of Diagrid Structural Systems with Conventional Structural Systems for different Plan Configurations