Design Phase Of Structures Research Articles

Knowledge-enhanced generative adversarial networks for schematic design of framed tube structures

In the schematic design phase of framed tube structures, component sizing is a vital task that requires expert experience and domain knowledge. Deep learning-based structural design methods enable machines to acquire expert experiences, but domain knowledge (e.g., empirical laws summarized by engineers from engineering practices) has not been embedded into such data-driven methods, resulting in common sense-conflicting designs. A knowledge-enhanced generative adversarial network is proposed by incorporating a novel differentiable evaluator for compliance checking of domain knowledge. A comparative study indicates that the proposed knowledge-enhanced method is 51% superior to the conventional data-driven method and 150 times faster than a competent engineer. The proposed method facilitates the schematic design of framed tube structures to be automatic and efficient, hence improving the productivity of structural engineers.

Structural grammar for design optimization of grid shell structures and diagrid tall buildings

A great attention has been recently paid to sustainability and efficiency in the field of civil engineering. In this context, structural optimization processes combined with shape grammar constitute an important tool to support the design phase of large scale structures. This paper proposes shape grammars for the topology optimization of grid shells and diagrid tall buildings characterized by triangulated patterns, with the aim to minimize the structural weight. The structural feasibility of the generated solutions is assessed through numerical analyses, while the optimized patterns are identified by means of optimization processes based on genetic algorithm. The results are provided in terms of optimal geometrical patterns, structural weight, stiffness/strength checks. The approach is helpful to support the investigation of lightweight structural patterns and structurally efficient solutions. The method could be expanded and improved by considering the minimization of different objective functions that take into account both the weight and construction aspects.

Numerical modelling of ice: Mechanical behaviour of ice under high strain rates

Ice impact is quite common and may become critical especially if it involves the transportation sector. Simulation tools may help in the structural design phase to increase the ability to withstand this kind of impact and/or to analyse the effect under extreme weather conditions. Such tools require an accurate description of the mechanical behaviour and therefore a detailed investigation about the dynamic mechanical properties of ice is of great interest. In the present work, material characterizations of ice, including tensile and compressive tests, were carried out under different strain rates. Two different material models (i.e., the modified Johnson-Cook model and Johnson-Holmquist II model) were calibrated. Then, impact tests using ice as a projectile with aluminium panels as a target were conducted to validate the material models of ice under impact loading. Furthermore, the replication effect of ice projectiles was investigated under different impact energies based on the mechanical responses and damage phenomena of ice for both models. Results showed that while both models are able to provide reliable predictions of the impact behaviour of ice projectiles, the Johnson-Holmquist II model presents a better performance as impact energy increases.

Integrated Schematic Design Method for Shear Wall Structures: A Practical Application of Generative Adversarial Networks

The intelligent design method based on generative adversarial networks (GANs) represents an emerging structural design paradigm where design rules are not artificially defined but are directly learned from existing design data. GAN-based methods have exhibited promising potential compared to conventional methods in the schematic design phase of reinforced concrete (RC) shear wall structures. However, for the following reasons, it is challenging to apply GAN-based approaches in the industry and to integrate them into the structural design process. (1) The data form of GAN-based methods is heterogeneous from that of the widely used computer-aided design (CAD) methods, and (2) GAN-based methods have high requirements on the hardware and software environment of the user’s computer. As a result, this study proposes an integrated schematic design method for RC shear wall structures, providing a workable GAN application strategy. Specifically, (1) a preprocessing method of architectural CAD drawings is proposed to connect the GAN with the upstream architectural design; (2) a user-friendly cloud design platform is built to reduce the requirements of the user’s local computer environment; and (3) a heterogeneous data transformation method and a parametric modeling procedure are proposed to automatically establish a structural analysis model based on GAN’s design, facilitating downstream detailed design tasks. The proposed method makes it possible for the entire schematic design phase of RC shear wall structures to be intelligent and automated. A case study reveals that the proposed method has a heterogeneous data transformation accuracy of 97.3% and is capable of generating shear wall layout designs similar to the designs of a competent engineer, with 225 times higher efficiency.

Performance of a prestressed efficiently prefabricated beam-column connection.

Analyzing the seismic performance and flexural capacity of beam-column joints is crucial in structural design phase. The purpose of this paper is to investigate the seismic performance and flexural capacity of precast prestressed efficiently fabricated frame (PPEFF) joints. Reverse cyclic load tests and flexural capacity analysis are conducted. The damage modes, hysteresis curves, skeleton curves, stiffness degradation, ductility, and energy dissipation capacity of five PPEFF joint specimens with different reinforcement rates of the energy-dissipating bars and shear reinforcement are obtained. The results show that the damage pattern of the specimen is ideal, i.e., the plastic hinge region at the end of the beam is severely damaged, whereas the remainder of the beam is slightly damaged. Increasing the reinforcement rate of the energy-consuming steel bars enhances the load capacity, energy dissipation capacity, and initial stiffness of the joint but reduces the ductility performance. The maximum change in ductility was 5.31 for the reinforcement rate of energy-consuming steel bars ranging from 0.38% to 0.59%. In addition, the flexural capacity of the PPEFF joint is evaluated, considering the influence of the shear steel on the yielding and ultimate states. An equation of the flexural capacity is derived. A good agreement is observed between the experimental and calculation results, verifying the correctness of the proposed flexural capacity equation.

A Novel Nonlinear Elasticity Approach for Analysis of Nonlinear and Hyperelastic Structures

There are many materials that the linear elasticity theory cannot predict their mechanical behavior against applied loads. This research proposes a comprehensive theoretical method to obtain the mechanical response of hyperelastic models (with nonlinear elastic deformations) such as polymers and rubbers. They are vital in the design phase of complicated engineering structures like engine mounts and structural bearings in aerospace and automotive industries. The presented theory is implemented in detail and has no limitations in analyzing geometrically and physically nonlinear materials. As a test case, the governing equations of a sheet made of nonlinear elastic material are derived within the framework of this new approach. The derived governing equations are completely nonlinear in all major directions. Consequently, results can be one of the most accurate mathematical simulation results for nonlinear elastic material structures. Then, the obtained equations are solved using a meshless solution method named the semi-analytical polynomial method. The stress and deformation results of the structure under uniform and non-uniform transverse external loadings are obtained for different types of boundary conditions, loading, and material properties. Consequently, this research can be widely used as a suitable essential reference for researchers studying the mechanical behavior of nonlinear elastic structures.

DESIGN PHASE OF A CYLINDRICAL LONG-SPAN COAL SHED WITH STEEL ARCH SPACE-TRUSS STRUCTURE

<p class="Text">This paper discusses the structural design phase of a long-span coal shed structure in a 2x50 MW steam power plant. This study aims to share knowledge on how to design a long-span coal shed structure safely based on the design standards. The main structural system of the coal shed roof is a steel arch space-truss with 120 m of span and 31 m of height above supporting 12.5 m height of reinforced concrete columns. The superstructure contains a roof system and reinforced concrete system. The substructure system consists of a tie beam, pile cap, and bore pile. In the numerical model, all structural members were idealized as frame elements, except the pile cap that to be idealized as shell elements. Then, the soil springs were assigned to the bore pile element nodals with a 1 m interval to simulate the soil-structure interaction. The gravity loads due to dead loads, additional dead loads, live loads, rain loads, and lateral loads due to wind action and earthquakes to be considered. Furthermore, the structural analysis was conducted with non-linear geometric to simulate the large displacement effects and tension only element of the wind bracing. In addition, a simplified method to estimate the structural stability under lateral load was conducted. Based on the structural analysis and structural design, the coal shed structure could fulfill the safety criteria in terms of ultimate and serviceability limit based on the design code criteria. Furthermore, the non-linear geometry and stability issue should be considered with an appropriate structural analysis method.</p>

Projeto ótimo de vigas pré-fabricadas e protendidas com foco na redução da emissão de CO2

Abstract Among the main contributors to CO2 emissions on the ozone layer, the construction industry contributes with a significant portion. This emission is generated largely by applying concrete construction systems and their variations. Therefore, it is important to use tools that allow the development of projects which mitigate the effects of harmful gas emissions into the atmosphere. Thus, this study applied an optimization algorithm called Firefly Algorithm (FA) to design precast and prestressed rectangular beams focusing on reducing CO2 emissions in the structural design phase. The Objective Function (OF) was defined as the total weight of CO2 emitted in each construction phase (production, transportation, and placement) and the structural design constraints are based on the design criteria established in ABNT NBR 6118. The problem optimization’s variables are geometric properties and mechanical beam's conditions, where the beam height, beam width, the proportion of height generates prestressing eccentricity, and the proportion of prestressing load were considered as design variables. Ten beams were analyzed, with different loadings, where each of these beams was submitted to the optimization process thirty times. For the proposed conditions, the ten beams had an average CO2 emission of 3282.59 kg, maximum and minimum carbon emission of 3630.52 kg and 2910.67 kg, respectively. The study resulted in a feasibility rate higher than 90%, showing that the optimization tool was efficient in the structural design phase focusing on sustainability. Concerning carbon emission, it is possible to verify a relationship between the increase of emission and the load since element with greater inertia tend to emit a greater amount of CO2. It was also possible to determine a regression between carbon emission and beam load.

Novel pharmaceutical cocrystal of lenalidomide with nicotinamide: Structural design, evaluation, and thermal phase transition study

Lenalidomide (LDM), widely used for the treatment of transfusion-dependent anaemia, has low oral bioavailability due to its poor aqueous solubility. Herein, we selected nicotinamide (NIC) as a coformer and synthesized a novel pharmaceutical cocrystal: lenalidomide-nicotinamide cocrystal (LNC) with a 1:1 stoichiometric ratio for enhancing the physicochemical properties of LDM, such as solubility and stability. For evaluating the ability to form cocrystal of LDM and NIC, a model of hydrogen-bond propensity (HBP) was utilized to calculate the hydrogen bond formation possibility for every hydrogen bond pair based on theexisting structuralinformation in the database. Afterward, solid-state grinding and liquid-assisted grinding methods were conducted to synthesize LNC, which were then characterized using powder X-ray diffraction, thermal and spectroscopic analysis. Besides, in the heating process, an interesting and anomalous phenomenon called thermal phase transition of the cocrystal was firstly observed and visualized by the hot stage microscope. Notably, the second thermal stage controlled by the vapor pressure of NIC was further determined experimentally and theoretically, which means that intermolecular hydrogen bonds gradually break when NIC occurs phase transition (from liquid to gas). Further, the physicochemical stability of cocrystal was proved reliable after being tested under accelerated stability conditions of 40 °C/75% RH for one month. Compared to lenalidomide and their physical mixture (molar ratio of 1:1), the dissolution and solubility of LNC have also been improved.

Estimation of delamination thickness in a multi-layered thermally thin structure by step heating thermography

The performance of a multi-layered structure is dependent upon its structural integrity. The main challenge posed to the structural integrity of such structures is the vulnerability of the interface to the formation of defects (like delamination, crack, void). Hence it becomes compelling to study such structures and propose methodologies that could detect and characterize the defects. This paper presents an approach to estimate the delamination thickness formed at the interface of a two-layered structure (a simple case of a multi-layered structure). An analytical expression of delamination thickness is derived using the electrical analogy approach. The saturation value of absolute thermal contrast, which is a characteristic feature of the thermal response of material or structure with defect under step heating has been used to derive the analytical expression of delamination thickness. The proposed approach is fast, simple, noncontact and devoid of extensive data handling. Simulations and experiments have been done to verify the approach. This approach can provide guidance during the design phase of multi-layered structures and aid in defining their failure threshold depending on the application. Additionally, it can also be implemented in manufacturing units during quality checks or can also be used for in situ defect characterization.

Optimum topological bracing design of tall steel frames subjected to dynamic loading

In this paper, a frame structural topology optimization methodology for the generation of moment resisting braced frames for tall buildings, considering dynamic seismic loading, is presented. Real-world loading conditions along with standardized steel profiles of Euronorm are employed. In the literature, the studies that employ the ground structure topology optimization method are limited mostly to truss structures under static loading conditions. The dynamic response in the framework of structural topology optimization remains a challenging problem, especially when the ground structure method is used for deriving the structural system of tall buildings. The contribution of this study to the state of the art, relies on the implementation of the proposed methodology in the conceptual design phase of civil engineering frame structures, where both axial and flexural stiffness is considered. Direct time integration methods are used, to implement forced vibrations and real recorded earthquake data in the topology optimization procedure, resulting to novel layouts for lateral resisting systems of tall buildings. Aiming to aid the engineer to the final design phase, the response spectrum modal analysis is employed and the seismic loading is applied according to the Eurocode 8.

Robust Optimal Damper Placement of Nonlinear Oil Dampers With Uncertainty Using Critical Double Impulse

A new robust method for optimal damper placement is presented for building structures under the critical double impulse. Oil dampers are treated here as representative supplemental dampers to control the seismic response of high-rise buildings. Such oil dampers usually obey a bi-linear force-velocity relation in controlling the maximum damping force through a relief mechanism to avoid the occurrence of excessive design forces in surrounding frames. The influence of uncertainty in characteristics of those bi-linear oil dampers on building structural safety is investigated. For the efficient evaluation of dynamic performance, the resonant critical double impulse is used as the base input instead of actual earthquake ground motions. Since the critical double impulse is determined to maximize the input energy to the objective building by changing the second impulse timing, uncertainties in input ground motions can be taken into account in a robust manner. To consider these various uncertainties, the robustness function based on the Info-Gap model is used in the robust optimization to assess structural performance variations caused by various uncertainties in the structural design phase. In this paper, a new innovative objective function in the robust optimal damper placement problem is proposed to enhance the robustness of structural performance under the variation of structural parameters by comparing the robustness function of the robust design with that of an ordinary optimal damper placement without considering uncertainties. Numerical examples of the robust optimal design of linear and bi-linear oil damper placements are shown for 10-story and 20-story planar building frame models. Structural performances of the robust optimal design to the conventional design earthquake ground motions are examined to investigate the validity of using the critical double impulse in the structural design under uncertainties.

Reliability-based Design Optimization of Laminated Composite Structures under Delamination and Material Property Uncertainties

Delamination is a major type of defects from manufacturing process in laminated composite structures, exhibiting uncertain characteristics which are represented by mixed random variables of continuous in-plane position and delamination size, as well as discrete through-the-thickness position, which should be considered in the design phase of composite structures. Thus, this paper presents a reliability-based design framework for optimal design of composite stacking sequence, for the first time to consider both delamination and material property uncertainties from manufacturing process. Mixed continuous-discrete random variables are involved, and a reliability analysis method is newly proposed to tackle this mixed-variable problem, maintaining high levels of both accuracy and efficiency. The formula of total probability is first employed to formulate the reliability constraint so that discrete and continuous random variables are decoupled; Monte Carlo simulation is then used for reliability analysis with respect to continuous random variables, and a surrogate modelling approach based on Gaussian process regression model is adopted to reduce computation costs. As design variables of ply angles are limited to a discrete set, a genetic algorithm with some proposed improvements is used to handle discrete design variables. Consequently, an optimization framework is devised for composite laminate design under uncertainties from manufacturing process, which is verified via case studies of a cantilever composite plate and can also be extended as a general solution for other composite laminates. With integrated consideration of manufacturing limitations and imperfections as well as structural performances, the presented framework provides a valuable tool in composite structure design.

A novel modeling approach for multi-passes butt-welded plates

Numerical simulation of welding process in the industrial field requires flexibility, speed, and accuracy at the same time. The use of conventional 3D models in detailed simulations of multi-pass welds is time-consuming, and it often slows down the design phase of large welded structures. Shell elements are usually employed in the finite element (FE) simulation of large structures like vessels and pipes. Nevertheless, employing a simple shell model to simulate multi-pass welds would most likely produce inaccurate outcomes. This article introduces a new equivalent parametric modeling methodology for the simulation of longitudinal multi-pass welds on plane structures, such as plates and rectangular hollow sections. The proposed Weld Equivalent Model (WEM) is made with single and multi-layer shell, link and beam elements. It helps detect residual stress and local distortion that are typical of multi-pass welds. This method employs thermal transient and steady-state structural analyses. The WEM model is generated by an automatic subroutine acting on a pre-existing FE shell model. In addition to this, a case study is reported of multi-pass welding of two plates featuring a V-shaped groove. This innovative weld modeling technique shows remarkable results and helps shorten computational time up to ten times compared to classical 3D numerical models.

The BIM-based Integrated Design of the SHiP Project Decay Volume

The Search for Hidden Particles (SHiP) experiment is a new general-purpose fixed target facility proposed at the CERN Super Proton Synchrotron accelerator to search for long- lived exotic particles associated with Hidden Sectors and Dark Matter. This paper reports on the BIM integrated design of SHiP’s decay volume, a conical steel vessel under vacuum that should host several large particle physics detector systems. The use of BIM characterized the design of the decay volume, both in the modeling and structural design phase, and in the process definition phase for the realization and implementation in the facility of the device. This procedure helps to minimize the risks of incorrect design and construction of the device during the whole process. With the automation of the virtual model and the use of interoperable software, in addition to speeding up the exchange of information, it is possible also to export the detailed information of the structural design directly to the numerical control machines for the prefabrication of the various steel modules. Then, the BIM approach to support the integrated design of the SHiP project decay volume from the conceptual planning to the construction phase is shown in this work.

3D-Assembled rutile TiO2spheres withc-channels for efficient lithium-ion storage

Three-dimensional (3D) TiO2 architectures have attracted significant attention recently as they can improve the electrochemical stability and realize the full potential of TiO2-based anodes in lithium ion batteries. Here, flower-like rutile TiO2 spheres with radially assembled nanorods (c-channels) were fabricated via a simple hydrothermal method. The 3D radial architecture affords massive active sites to fortify the lithium storage. Moreover, the presence of c-channels facilitates electrolyte infiltration and offers facile pathways for efficient Li+ transport. As a result, this flower-like rutile TiO2 anode gives significantly enhanced specific capacities (615 mA h g-1 at 1 C and 386 mA h g-1 at 2 C after 400 cycles) and a superior long-term cyclability (up to 10 000 cycles with a specific capacity of 67 mA h g-1 at 100 C). Kinetic analysis reveals that the enhanced diffusion-controlled and surface capacitive storage leads to the excellent electrochemical behavior. This work not only exhibits the enormous advantages of 3D architectures with c-channels, but also provides access to structural design and crystal phase selection for TiO2-based anode materials.

LCA-Based Investigation of Environmental Impacts for Novel Double-Beam Floor System Subjected to High Gravity Loads

In populated downtown areas, a floor system with secured environmental performance is needed to reduce greenhouse gases (GHGs) and global warming problems related to buildings. This study aims to assess environmental impacts on a novel double-beam floor system subjected to high gravity loads. Life cycle assessment (LCA) was conducted to investigate the environmental impacts on the reduction in construction materials by calculating global warming potential (GWP) in the structural design phase. For different structural systems, the environmental performance was compared based on the GWP, and the contributions of structural elements to the GWP in each structural system were analyzed. The rotational constraints induced by the beam-end concrete panel can significantly reduce the GWP of the double-beam floor system by up to 13.8% compared to the conventional beam-girder system. Thus, the double-beam floor system reinforced with the concrete panel can be a candidate for eco-friendly structural systems in underground structures requiring high gravity loads. This result provides valuable findings that the structural effect on the rotational constraint of the concrete panel was quantitatively evaluated by converting it into an environmental impact.

An approximate closed-form buckling solution for the local skin buckling of stiffened plates with omega stringers: The case of antisymmetric cross-ply and angle-ply laminations

Estimating the buckling resistance of stiffened plates with detailed numerical models can provide high fidelity results, but for the preliminary design phase of aircraft structures this is impractical, since numerous iterations or sensitivity analyses are required. Analytical solutions become preferable for this design phase. To this end, an approximate closed-form solution is developed to estimate the critical skin local buckling load of stiffened plates with omega stringers with antisymmetric cross-ply and angle-ply lamination. This is obtained using an innovative energy-based homogenization method that yields to an equivalent bending stiffness matrix. The research further examines the influence of two key parameters to the analytical estimation of the buckling load of the fore mentioned partially anisotropic skin. The first parameter concerns the selection of the appropriate boundary conditions that must be assumed for the skin-stringer junction. The mathematical model considers the part of the skin between two consecutive omega stringers. The rest of the stiffened plate is replaced by equivalent transverse and rotational springs, which act as elastic edge supports. The elastic restraints are determined with two distinctive approaches considering the bending and torsional stiffness of the omega stringers. As a second parameter two different deflection functions (trigonometric and polynomial) are considered for the Rayleigh-Ritz method. Aim is to determine the appropriate combination of elastic restrain stiffness and deflection function that yield to more accurate buckling results for the cases of antisymmetric cross-ply and angle-ply skin laminations. Finally, the obtained analytical results are evaluated by comparing them with the respective numerical. The comparison showed that a satisfactory correlation can be achieved, for a certain combination of boundary conditions and deflection functions. Discussion and conclusions regarding the accuracy, discrepancies and limitations of the derived buckling solution are highlighted.

Construction Kit of RF-Blocks in Package Technologies

Abstract Advanced packages are necessary to cope with the requirements of 5G and radar technologies with 60 GHz and beyond. For proper RF design with rising package technology requirements demands for usage of predefined structures with predefined layout elements, manufactured and measured elements. This paper deals with an approach to have such elements available to build advanced types of packages in shorter time compared to classical approaches. The approach is a general approach but it is demonstrated with an advanced two-level package-on-package technology with a leading edge IC technology. It is also used explain the build-up of a construction kit of RF-blocks from the design phase of test structures up to measurement of such structures, qualification and model building. From the test structure more general structures can be derived and used in the design of future 5G applications. This enables better time-to-market, reduces cost and provides higher design validation in terms of first time right.

Three‐in‐One Process to Enhance the Oxygen Evolution Activity of Tungstates: Phase Transformation, Ordered Mesoporous Structure, and Cations Synergistic Effect

Engineering compositions and structures is the tactic for optimizing electrocatalytic properties in nanomaterials. High‐ordered mesoporous monometallic or bimetallic tungstates are first synthesized via a soft template method combined with pH regulation of the reaction solution. The addition of buffer solution not only changes the phase composition but also adjusts the hydrolysis and condensation rate to promote the formation of a mesoporous structure with the help of the template. Mesoporous cobalt‐doped iron tungstates deliver 320 mV at a current density of 10 mA cm−2 with a small Tafel slope of 52 mV dec−1, due to transformation of phase, the existence of a mesoporous structure, and the synergistic effect of metallic cations. Herein, it is confirmed that the simplicity and feasibility of rational structure design and purposive phase regulation provide vast opportunities and strategies for the research of novel oxygen evolution catalysts.