Timber-Concrete Composite Structural Elements

2021 ◽  
Author(s):  
Anita Ogrin ◽  
Tomaž Hozjan
Keyword(s):  
Tensile Strength ◽  
Composite Structures ◽  
Wood Products ◽  
Structural Elements ◽  
Long Span Bridges ◽  
Long Span ◽  
Bending Load ◽  
Engineered Wood Products ◽  
Floor Systems ◽  
Connection Type

Timber-concrete composites are interesting engineered wood products usually used for structural elements, which are mainly subjected to bending load; from simple floor systems to long-span bridges. This way, the advantage can be taken of timber tensile strength and concrete compression strength. The chapter begins with an introduction of various types of timber-concrete composite structural elements regarding type of the element, connection type and types of timber and concrete. Next, specific characteristics and advantages of timber-concrete composite structural elements are thoroughly discussed from viewpoints of engineering, architecture, builders and ecology. Furthermore, basic mechanical principles of timber-concrete composite structural elements are presented and some design methods are briefly described. Finally, worldwide inclusion of timber-concrete composite structures in currently applicable standards is discussed.

scholarly journals Theoretically optimal forms for very long-span bridges under gravity loading

2018 ◽  
Vol 474 (2217) ◽  
pp. 20170726 ◽  
Author(s):  
Helen E. Fairclough ◽  
Matthew Gilbert ◽  
Aleksey V. Pichugin ◽  
Andy Tyas ◽  
Ian Firth
Keyword(s):  
Bridge Deck ◽  
Optimization Procedure ◽  
Layout Optimization ◽  
The Self ◽  
Minimum Volume ◽  
Structural Elements ◽  
Optimal Form ◽  
Long Span Bridges ◽  
Cable Stayed Bridge ◽  
Long Span

Long-span bridges have traditionally employed suspension or cable-stayed forms, comprising vertical pylons and networks of cables supporting a bridge deck. However, the optimality of such forms over very long spans appears never to have been rigorously assessed, and the theoretically optimal form for a given span carrying gravity loading has remained unknown. To address this we here describe a new numerical layout optimization procedure capable of intrinsically modelling the self-weight of the constituent structural elements, and use this to identify the form requiring the minimum volume of material for a given span. The bridge forms identified are complex and differ markedly to traditional suspension and cable-stayed bridge forms. Simplified variants incorporating split pylons are also presented. Although these would still be challenging to construct in practice, a benefit is that they are capable of spanning much greater distances for a given volume of material than traditional suspension and cable-stayed forms employing vertical pylons, particularly when very long spans (e.g. over 2 km) are involved.

Alternate Designs for Long Span Bridges

PCI Journal ◽  
1980 ◽  
Vol 25 (4) ◽  
pp. 48-58
Author(s):  
Felix Kulka
Keyword(s):  
Long Span Bridges ◽  
Long Span

Wind Buffeting in Time Domain Analysis of Long-Span Bridges using RM Bridge

2017 ◽  
Vol 109 (6) ◽  
pp. 3307-3317
Author(s):  
Afshin Hatami ◽  
Rakesh Pathak ◽  
Shri Bhide
Keyword(s):  
Time Domain ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Long Span Bridges ◽  
Long Span

Microstructure and physical properties of composite nonwovens produced by incorporating cotton fibers in elastic spunbond and meltblown webs for medical textiles

2021 ◽  
pp. 152808372110042
Author(s):  
Partha Sikdar ◽  
Gajanan S Bhat ◽  
Doug Hinchliff ◽  
Shafiqul Islam ◽  
Brian Condon
Keyword(s):  
Tensile Strength ◽  
Physical Properties ◽  
Composite Structures ◽  
High Surface ◽  
High Surface Area ◽  
Barrier Properties ◽  
Cotton Fibers ◽  
Adult Care ◽  
Medical Textiles ◽  
Improved Performance

The objective of this research was to produce elastomeric nonwovens containing cotton by the combination of appropriate process. Such nonwovens are in demand for use in several healthcare, baby care, and adult care products that require stretchability, comfort, and barrier properties. Meltblown fabrics have very high surface area due to microfibers and have good absorbency, permeability, and barrier properties. Spunbonding is the most economical process to produce nonwovens with good strength and physical properties with relatively larger diameter fibers. Incorporating cotton fibers into elastomeric nonwovens can enhance the performance of products, such as absorbency and comfort. There has not been any study yet to use such novel approaches to produce elastomeric cotton fiber nonwovens. A hydroentangling process was used to integrate cotton fibers into produced elastomeric spunbond and meltblown nonwovens. The laminated web structures produced by various combinations were evaluated for their physical properties such as weight, thickness, air permeability, pore size, tensile strength, and especially the stretch recovery. Incorporating cotton into elastic webs resulted in composite structures with improved moisture absorbency (250%-800%) as well as good breathability and elastic properties. The results also show that incorporating cotton can significantly increase tensile strength with improved spontaneous recovery from stretch even after the 5th cycle. Results from the experiments demonstrate that such composite webs with improved performance properties can be produced by commercially used processes.

scholarly journals Wind-Induced Phenomena in Long-Span Cable-Supported Bridges: A Comparative Review of Wind Tunnel Tests and Computational Fluid Dynamics Modelling

2021 ◽  
Vol 11 (4) ◽  
pp. 1642
Author(s):  
Yuxiang Zhang ◽  
Philip Cardiff ◽  
Jennifer Keenahan
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Careful Analysis ◽  
Wind Effects ◽  
Wind Tunnel Tests ◽  
Long Span Bridges ◽  
Long Span ◽  
Comparative Review ◽  
Dynamics Modelling

Engineers, architects, planners and designers must carefully consider the effects of wind in their work. Due to their slender and flexible nature, long-span bridges can often experience vibrations due to the wind, and so the careful analysis of wind effects is paramount. Traditionally, wind tunnel tests have been the preferred method of conducting bridge wind analysis. In recent times, owing to improved computational power, computational fluid dynamics simulations are coming to the fore as viable means of analysing wind effects on bridges. The focus of this paper is on long-span cable-supported bridges. Wind issues in long-span cable-supported bridges can include flutter, vortex-induced vibrations and rain–wind-induced vibrations. This paper presents a state-of-the-art review of research on the use of wind tunnel tests and computational fluid dynamics modelling of these wind issues on long-span bridges.

scholarly journals Damage Identification of Long-Span Bridges Using the Hybrid of Convolutional Neural Network and Long Short-Term Memory Network

Algorithms ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 180
Author(s):  
Lei Fu ◽  
Qizhi Tang ◽  
Peng Gao ◽  
Jingzhou Xin ◽  
Jianting Zhou
Keyword(s):  
Short Term Memory ◽  
Damage Identification ◽  
Identification Accuracy ◽  
Damage Localization ◽  
Short Term ◽  
Term Memory ◽  
Localization Accuracy ◽  
Long Span Bridges ◽  
Long Span ◽  
Long Short Term Memory

The shallow features extracted by the traditional artificial intelligence algorithm-based damage identification methods pose low sensitivity and ignore the timing characteristics of vibration signals. Thus, this study uses the high-dimensional feature extraction advantages of convolutional neural networks (CNNs) and the time series modeling capability of long short-term memory networks (LSTM) to identify damage to long-span bridges. Firstly, the features extracted by CNN and LSTM are fused as the input of the fully connected layer to train the CNN-LSTM model. After that, the trained CNN-LSTM model is employed for damage identification. Finally, a numerical example of a large-span suspension bridge was carried out to investigate the effectiveness of the proposed method. Furthermore, the performance of CNN-LSTM and CNN under different noise levels was compared to test the feasibility of application in practical engineering. The results demonstrate the following: (1) the combination of CNN and LSTM is satisfactory with 94% of the damage localization accuracy and only 8.0% of the average relative identification error (ARIE) of damage severity identification; (2) in comparison to the CNN, the CNN-LSTM results in superior identification accuracy; the damage localization accuracy is improved by 8.13%, while the decrement of ARIE of damage severity identification is 5.20%; and (3) the proposed method is capable of resisting the influence of environmental noise and acquires an acceptable recognition effect for multi-location damage; in a database with a lower signal-to-noise ratio of 3.33, the damage localization accuracy of the CNN-LSTM model is 67.06%, and the ARIE of the damage severity identification is 31%. This work provides an innovative idea for damage identification of long-span bridges and is conducive to promote follow-up studies regarding structural condition evaluation.

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