Linear Buckling Analysis Considering No-compression Property of Metal Grid Shells Stiffened by Tension Braces

In order to analyze the buckling behavior of lattice shells stiffened by cables or slender braces without pre-tension, it is necessary to consider the no-compression property of braces. This paper proposes an innovative method of linear buckling analysis that considers the no-compression property of braces. Moreover, in order to examine the proposed method's validity, its results are compared with the results from a nonlinear buckling analysis with geometrical nonlinearity and material nonlinearity to express the no-compression property of braces. The results show that the proposed method can well-predict the buckling behaviors of lattice shells stiffened by tension braces.

Shaping Indeterminate Frames

The large impact of building structures on the environment must be reduced to meet the global targets fixed by the Intergovernmental Panel on Climate Change. Standard building structures with constant prismatic cross-section have material inefficiencies of around 66% (and up to 75% in some cases) that need to be addressed. Structural shaping, a subfield of shape optimization, offers a pathway to reduce the impact of building materials on the environment. Shaping statically determinate structures such as simply supported beams is relatively straightforward, but offers few design options compared to statically indeterminate structures. However, no methods provide an efficient way for designers to shape these systems according to their design intent or efficiency goals. Based on plasticity theory, this paper presents a shaping methodology to explore the design space of shaped indeterminate frame structures. The methodology is implemented in three case studies.<br/> In all the case studies, the methodology allows for the exploration of material-efficient yet diverse designs of shaped indeterminate frame structures. The implementation of this methodology can promote the use of structural shaping by offering more agency to structural designers to create diverse and efficient structural systems.

Prefabrication of a Thin Concrete Shell: The Case of St Kevin's Church in Dee Why, Australia

Location of Project: Dee Why, NSW, Australia<br/> Structural Type: Prefabricated thin concrete shell <br/> Project Scale: Length 30 m, width 15.5 m, height 12 m <br/> Owner/Client: Warringah Catholic Parish <br/> Architect: Gibbons & Gibbons Architects <br/> Structural Engineer: Concrete Industries Australia (Monier) Engineers Pty. Ltd.<br/> Construction: Concrete Industries Australia (Monier) Pty. Ltd. <br/> Construction year: 1961<br/>

Cable Force Measurement Technology and Engineering Application

With the continuous development of prestressing technology, cables have been widely used in structural engineering. A special concern in practical engineering is selecting the appropriate cable force measurement technology. This paper analyzes and introduces the principle of cable force measurement technology commonly used in current engineering from three aspects, namely, strain, vibration and wave fluctuation, and force balance. Combined with an actual project, the selection and arrangement of measuring points in the cable pre-tension measurement and other issues are discussed. The engineering example shows that the cable force measurement method based on FBG sensor presented in this paper can capture the action of each construction tensioning operations in real time and accurately. Monitoring the tension of the structure in real time is convenient for engineers and technician. The process is suitable for cable force monitoring during the construction tensioning stage. Furthermore, the EM sensor has good stability and durability and is suitable for long-term cable force monitoring.

Evolutionary Topology Optimization of Spatial Steel-Concrete Structures

Topology optimization techniques based on finite element analysis have been widely used in many fields, but most of the research and applications are based on single-material structures. Extended from the bi-directional evolutionary structural optimization (BESO) method, a new topology optimization technique for 3D structures made of multiple materials is presented in this paper. According to the sum of each element's principal stresses in the design domain, a material more suitable for this element would be assigned. Numerical examples of a steel- concrete cantilever, two different bridges and four floor systems are provided to demonstrate the effectiveness and practical value of the proposed method for the conceptual design of composite structures made of steel and concrete.

Numerical Impact Analysis of Folding-Induced Tubular Thin-walled Energy-dissipating Elements

This paper deals with the numerical impact analysis of tubular thin-walled steel-made elements with induced folding for energy dissipation application. The excellent deceleration of the impacting mass of axial collapsing structures favors their use in energy dissipation applications, such as impact resistance and rockfall protection. Dynamic Finite Element analyses have been carried out to evaluate the performance of vertical assemblies of cold-formed steel cell-shaped elements welded on each other to form collapsible tubular elements. In turn, these have been gathered in groups and restrained by galvanized steel wires to create modules. The axial collapse, which is the most effective energy absorption mechanism, has been triggered by shaping the elements' edge as serpentine. In the analysis, several assembly configurations have been subjected to a freefall rhombicuboctahedron-shaped rigid block impact; Falling height, impact angle, and block mass have been varied to investigate their effect on the performance. The numerical results show a good agreement when compared to those obtained through a real-scale experiment.

Computational Modeling and Energy Absorption Behavior of Thin-Walled Tubes with the Kresling Origami Pattern

Origami structures have been widely used in various engineering fields due to their desirable properties such as geometric transformability and high specific energy absorption. Based on the Kresling origami pattern, this study proposes a type of thin-walled origami tube the structural configuration of which is found by a mixed-integer linear programming model. Using finite element analysis, a reasonable configuration of a thin-walled tube with the Kresling pattern is firstly analyzed. Then, the influences of different material properties, the rotation angle of the upper and lower sections of the tube unit, and cross-sectional shapes on the energy absorption behavior of the thin-walled tubes under axial compression are evaluated. The results show that the symmetric thin-walled tube with the Kresling pattern is a reasonable choice for energy absorption purposes. Compared with thin-walled prismatic tubes, the thin-walled tube with the Kresling pattern substantially reduces the initial peak force and the average crushing force, without significantly reducing its energy absorption capacity; moreover, it enters the plastic energy dissipation stage ahead of time, giving it a superior energy absorption performance. Besides, the material properties, rotation angle, and cross-sectional shape have considerable influences on its energy absorption performance. The results provide a basis for the application of the Kresling origami pattern in the design of thin-walled energy-absorbingstructures.

Shape Generation of Bending-Active Braced Arches Based on Elastica Curves

The active bending concept provides a new perspective for a well-established structural type which has been used at various scales: the beam-string, consisting of a beam with an attached lower tie in tension and bracing struts balancing the forces between them. The idea goes back to the gutter beams of the Crystal Palace and has been widely used to the present for large-scale structures. When a slender beam is used, the tension in the tie induces curvature in the beam and increases the structural depth of the system; this opens new formal possibilities and results in lightweight structures at the expense of increasing their overall flexibility. Systems of this kind fall within the realm of active bending. We name them bending-active braced arches. The target shape of the system follows the tensioning process and needs to be pre-determined by means of a specific analysis, typically involving dynamic relaxation or optimization-based methods. In this paper, we propose an analytical method to generate shapes for bending-active braced arches. It assumes that each segment of the activated rod between deviators behaves as a segment of elastica; this enables the use of closed-form expressions to evaluate the shape and induced stress level in the active member. Taking advantage of this idea, it is possible to devise a procedure to carry out the shaping process in a sequential way by adequately choosing the design parameters. When alternative choices for the parameters are selected, the problem becomes non-linear and can be solved using suitable techniques. Some examples with different design constraints have been reproduced to illustrate the possibilities of the method.

Structural Morphogenesis for RC Free-Form Surface Shell with Arbitrary Boundary Shape And Opening - Comparison of Optimal Solution and Application of Decent Solutions Search Method

In this paper, artificial bee colony (ABC) to obtain the decent solutions that the authors proposed is applied to the structural morphogenesis for RC (Reinforced-Concrete) free-form surface shell with arbitrary boundary shape. The 'decent solutions' have relatively high evaluation solutions that maintain the diversity of the design variable space, including the global optimal solution and local optimal solutions. In this paper, we focus on an opening of RC free form surface shell structures considering design and functionality, and the structural morphogenesis procedure that considers constraints of the excessive bending moment caused by the presence of an opening in the shell is proposed. Numerical results demonstrate the efficacy of a structural morphogenesis procedure that simultaneously considers shell shape, thickness, and opening as design variables. Furthermore, it is shown that proposed structural morphogenesis using decent solutions search method can support a designer's idea of architectural forms having a relationship between shape and mechanical behavior at the initial stage of design.

Next Generation Parametric Design

This paper presents a novel, next-generation, cloud-native parametric and associative platform for digital knowledge, services and automation, and the rationalisation behind the development of and the need for this platform in relation to the history of computational design and engineering, and the advantages and limitations of each step in this evolution: Computer Aided Design (CAD), Building Information Modelling (BIM), Finite Element Analysis (FEA), Parametric and Associative Design (PAD), Generative Design and programming approaches to design and engineering. The paper discusses some of the key functionalities in relation to why they are useful as a next step in the digital transformation of the Architecture, Engineering and Construction (AEC) industry. The paper concludes with some of the challenges for the near future of this platform.