Frequency-amplitude of Vibration of Modern Aesthetic Footbridges for Walking and Cycling

2021 ◽  
Author(s):  
Carlos Sousa Oliveira ◽  
Ana Luísa VIEIRA
Keyword(s):  
Dynamic Characteristics ◽  
Mechanical Characteristics ◽  
Structural Materials ◽  
Environmental Context ◽  
Complex Geometries ◽  
Minimal Cost ◽  
Cost Of Construction

<p>New urban developments are changing the traditional footbridges by contemplating (i) the new cyclic functionality of these structures, (ii) the wood and other light structural materials and, in many cases, (iii) the introduction of aesthetics. Previous studies were made on pedestrian footbridges composed by a simple supported beam with uniform distributed characteristics. The main objective of these past projects was to pass pedestrians across, safe and comfortably, with minimal cost of construction, without much aesthetics.</p><p>Nowadays, footbridges appeal to the best architects and engineering consortiums and each new one is viewed as entering in an aesthetic contest. The objective now is similar as referred before but, besides adding the cycling vehicles, they should look into aesthetics and to the environmental context. They span larger distances making use of more adequate materials. However, the dynamic characteristics might be a problem due to proximity of frequencies of the structure with the rhythm of the stepping of crossing. This is the objective of this paper to understand if more complex geometries and different materials pose problems. After looking into several cases in Portugal and Spain and, describing their main geometric and mechanical characteristics, the most important frequencies of vibration and amplitude of oscillation for various loadings were analyzed. Caution should be exercised to not excite resonance conditions. A case study of one of these structures is analysed in detail for deterministic conditions. Cycling is not a problem.</p>

scholarly journals An Optimization Workflow in Design for Additive Manufacturing

2021 ◽  
Vol 11 (6) ◽  
pp. 2572
Author(s):  
Stefano Rosso ◽  
Federico Uriati ◽  
Luca Grigolato ◽  
Roberto Meneghello ◽  
Gianmaria Concheri ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Structural Optimization ◽  
Geometric Model ◽  
Complex Geometries ◽  
Design Phase ◽  
Design For Additive Manufacturing ◽  
Engineering Software ◽  
Embodiment Design ◽  
Pros And Cons

Additive Manufacturing (AM) brought a revolution in parts design and production. It enables the possibility to obtain objects with complex geometries and to exploit structural optimization algorithms. Nevertheless, AM is far from being a mature technology and advances are still needed from different perspectives. Among these, the literature highlights the need of improving the frameworks that describe the design process and taking full advantage of the possibilities offered by AM. This work aims to propose a workflow for AM guiding the designer during the embodiment design phase, from the engineering requirements to the production of the final part. The main aspects are the optimization of the dimensions and the topology of the parts, to take into consideration functional and manufacturing requirements, and to validate the geometric model by computer-aided engineering software. Moreover, a case study dealing with the redesign of a piston rod is presented, in which the proposed workflow is adopted. Results show the effectiveness of the workflow when applied to cases in which structural optimization could bring an advantage in the design of a part and the pros and cons of the choices made during the design phases were highlighted.

Rock mechanical characteristics of deep marine shale in southern China, a case study in Dingshan block

2021 ◽  
pp. 108699
Author(s):  
Lei Wang ◽  
Yintong Guo ◽  
Jun Zhou ◽  
Hanzhi Yang ◽  
Chunhe Yang ◽  
...  
Keyword(s):  
Mechanical Characteristics ◽  
Southern China ◽  
Marine Shale

scholarly journals Monitoring and Analysis of Dynamic Characteristics of Super High-rise Buildings using GB-RAR: A Case Study of the WGC under Construction, China

2020 ◽  
Vol 10 (3) ◽  
pp. 808 ◽  
Author(s):  
Lv Zhou ◽  
Jiming Guo ◽  
Xuelin Wen ◽  
Jun Ma ◽  
Fei Yang ◽  
...  
Keyword(s):  
Wavelet Analysis ◽  
Dynamic Characteristics ◽  
Horizontal Displacement ◽  
Dynamic Monitoring ◽  
High Rise ◽  
The North ◽  
Study Results ◽  
Under Construction ◽  
East West

Accurate dynamic characteristics of super high-rise buildings serve as a guide in their construction and operation. Ground-based real aperture radar (GB-RAR) techniques have been applied in monitoring and analyzing the dynamic characteristics of different buildings, but only few studies have utilized them to derive the dynamic characteristics of super high-rise buildings, especially those higher than 400 m and under construction. In this study, we proposed a set of technical methods for monitoring and analyzing the dynamic characteristics of super high-rise buildings based on GB-RAR and wavelet analysis. A case study was conducted on the monitoring and analysis of the dynamic characteristics of the Wuhan Greenland Center (WGC) under construction (5–7 July 2017) with a 636 m design height. Displacement time series was accurately derived through GB-RAR and wavelet analysis, and the accuracy reached the submillimeter level. The maximum horizontal displacement amplitudes at the top of the building in the north–south and east–west directions were 18.84 and 15.94 mm, respectively. The roof displacement trajectory of the WGC was clearly identified. A certain negative correlation between the temperature and displacement changes at the roof of the building was identified. Study results demonstrate that the proposed method is effective for the dynamic monitoring and analysis of super high-rise buildings with noninvasive and nondestructive characteristics.

Biomimetic tough helicoidally structured material through novel electrospinning based additive manufacturing

MRS Advances ◽  
2019 ◽  
Vol 4 (43) ◽  
pp. 2345-2354 ◽  
Author(s):  
Komal Agarwal ◽  
Rahul Sahay ◽  
Avinash Baji ◽  
Arief S. Budiman
Keyword(s):  
Structural Design ◽  
Polyvinylidene Fluoride ◽  
Architectural Design ◽  
Mechanical Characteristics ◽  
Near Field ◽  
Structural Materials ◽  
Electrospinning Technique ◽  
Mantis Shrimp ◽  
Novel Method ◽  
Microstructural Design

ABSTRACTNatural structural materials (NSMs) such as nacre, teeth, bones and crustacean exoskeleton are usually made of weak biomaterials arranged in specific structural design imparting them remarkable mechanical characteristics. Such hierarchical structural layouts found in nature encourage designing of mechanically desirable synthetic structural materials (SSMs). Among variety of natural hierarchical layouts, this paper specifically focuses on helicoidal architectural design found in the tough dactyl club of mantis shrimp. We first decode the mechanics behind helicoidal microstructural design and document the development of impact resistant macroscale helicoidal architectured synthetic structural materials (HA-SSMs). Next, near-field electrospinning technique (NFES)- both melt (polycaprolactone) and solution (polyvinylidene fluoride) type has been discussed in detail, as a novel method for developing lab scale 3D biomimetic HA-SSMs in micro-nanoscale. Further, the effect of the helical arrangement, size of substructures and surface treatment on strength and toughness of NFES fabricated HA-SSMs samples is analysed.

scholarly journals The Agency of the Displaced? Roman Expansion, Environmental Forces, and the Occupation of Marginal Landscapes in Ancient Italy

Humanities ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 116 ◽  
Author(s):  
Elisa Perego ◽  
Rafael Scopacasa
Keyword(s):  
Social Groups ◽  
Environmental Context ◽  
Key Players ◽  
Displaced People ◽  
The Mediterranean ◽  
Material Evidence

This article approaches the agency of displaced people through material evidence from the distant past. It seeks to construct a narrative of displacement where the key players include human as well as non-human agents—namely, the environment into which people move, and the socio-political and environmental context of displacement. Our case-study from ancient Italy involves potentially marginalized people who moved into agriculturally challenging lands in Daunia (one of the most drought-prone areas of the Mediterranean) during the Roman conquest (late fourth-early second centuries BCE). We discuss how the interplay between socio-political and environmental forces may have shaped the agency of subaltern social groups on the move, and the outcomes of this process. Ultimately, this analysis can contribute towards a framework for the archaeological study of marginality and mobility/displacement—while addressing potential limitations in evidence and methods.

scholarly journals Dynamic Characteristics of Hanging Truss Having Shape Memory Alloy Wires

2017 ◽  
Vol 7 (2) ◽  
pp. 6 ◽  
Author(s):  
Xuan Zhang ◽  
Kazuyuki Hanahara ◽  
Yukio Tada
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Dynamic Characteristics ◽  
Dynamic Problem ◽  
Vibration Isolation ◽  
Mechanical Characteristics ◽  
Structural System ◽  
Vibration Attenuation ◽  
Calculation Process ◽  
Absorption Characteristics

In this study, we discuss the dynamics of a type of hanging truss structural system consisting of rigid and wire members, part of which are SMA (shape memory alloy) wires. This kind of truss structure has the capability of vibration isolation and absorption. Characteristics of zero compressive stiffness of wire members, SMA wire members and hanging configuration of the structure itself contribute to the effect of vibration isolation. The hysteretic loop of SMA wires plays a significant role in vibration attenuation. Mathematical models for this kind of dynamic problem are developed. Calculation process is introduced to take into account the mechanical characteristics of SMA and wire members. Dynamic characteristics are discussed; simultaneously, the effects of vibration isolation and attenuation have been confirmed. On the basis of the numerical calculations, advantages of combinations of various types of wire members, including the truss units having no bracing wires have been demonstrated. 

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