scholarly journals Effect of Shape Modification on I Girder and Box Girder Prestressed Concrete to Stiffness and Displacement

2021 ◽  
Vol 27 (1) ◽  
pp. 97-106
Author(s):  
Hakas Prayuda
Keyword(s):  
Cross Sections ◽  
Prestressed Concrete ◽  
Span Length ◽  
Shape Modification ◽  
Cross Sectional ◽  
Box Girder ◽  
Normal Loading ◽  
Total Cross Sectional Area ◽  
Earthquake Load ◽  
Manual Calculation

Prestressed concrete has been widely used in structural buildings, especially for big span length purposes. The prestressed concrete dimension cross sections normally are fixed, provided by the factory based on their experience for every span length. However, this size aspect can be developed to make better improvement. In this study, I and box girder shapes were modified with the same total cross-sectional area. Three types of modification have been made for each girder shape by giving the space on the middle for I girder and changing form from trapezoidal to rectangular section for box girder. The number of steel tendons for this research was made typically and same so that the stress and displacement can be compared fairly. Manual calculation was performed for all samples and was completed under three circumstances namely initial condition, loading condition, and final condition. Also, the manual calculation is according to Indonesian provisions, which are SNI 2833-2016 for the earthquake load and SNI 1725-2016 for normal loading on bridges. From the result, it is known that one shape for each girder shape has met the criteria for the smallest stress and displacement.

Genetic Effects on Skeletal Mechanosensitivity in Mice

2002 ◽  
Author(s):  
Charles H. Turner ◽  
Alexander G. Robling
Keyword(s):  
Mechanical Loading ◽  
Cross Sections ◽  
Inbred Mouse ◽  
Cross Sectional Area ◽  
Mouse Strains ◽  
Sectional Area ◽  
Mineral Density ◽  
Bone Apposition ◽  
Cross Sectional ◽  
Total Cross Sectional Area

The accumulation of bone mass during growth can be enhanced by environmental factors such as mechanical loading (exercise) or calcium intake, but 60–70% of the variance in adult bone mineral density (BMD) is explained by heredity. Consequently, understanding the signaling pathways targeted by the genes governing bone accumulation holds perhaps the greatest potential in reducing fracture incidence later in life. Rodent models are particularly useful for studying the genetics of skeletal traits. Of the available inbred mouse strains, three in particular have been studied extensively in skeletal genetics: C57BL/6, DBA/2, and C3H/He. The C57BL/6 strain is characterized by low BMD and large total cross-sectional area (CSA) in the midshaft femur; the C3H/He strain exhibits very high femoral BMD and a smaller femoral CSA than the C57BL/6 mice; and DBA/2 mice have moderately high femoral BMD and a very small midshaft femur CSA. Mechanical loading of the skeleton during growth can substantially enhance periosteal bone apposition, and ultimately produce a diaphyseal cross section with enlarged area. Therefore we hypothesized that the mouse strain with greater femoral cross-sectional area (C57BL/6) might have a genetic predisposition for greater mechanosensitivity than mice with smaller cross sections (C3H/He and DBA/2).

scholarly journals Effect of Construction Method on Shear Lag in Prestressed Concrete Box Girders

2012 ◽  
Vol 2012 ◽  
pp. 1-17 ◽  
Author(s):  
Shi-Jun Zhou
Keyword(s):  
Cross Sections ◽  
Prestressed Concrete ◽  
Construction Process ◽  
Shear Lag ◽  
Box Girders ◽  
Box Girder ◽  
Construction Methods ◽  
Concrete Box Girder ◽  
Concrete Box Girder Bridges ◽  
Girder Bridge

Most of the previous researches conducted on shear lag of box girders were only concerned about simple types of structures, such as simply supported and cantilever beams. The structural systems concerned in these previous researches were considered as determined and unchangeable. In this paper, a finite element method considering shear lag and creep of concrete was presented to analyze the effect of dynamic construction process on shear lag in different types of concrete box-girder bridges. The shear lag effect of the three types of a two-span continuous concrete beam classified by construction methods was analyzed in detail according to construction process. Also, a three-span prestressed concrete box-girder bridge was analyzed according to the actual construction process. The shear lag coefficients and stresses on cross sections along the beam including shear lag were obtained. The different construction methods, the changes of structural system with the construction process, the changes of loading and boundary conditions with the construction process and time, the prestressing, and creep were all imitated in the calculations. From comparisons between the results for beams using different construction methods, useful conclusions were made.

scholarly journals Comparison investigation on the load capacity of octagonal, circular and square concrete filled steel tubes

2018 ◽  
Author(s):  
Tak-Ming Chan ◽  
Jiong-Yi Zhu
Keyword(s):  
Cross Sections ◽  
Load Capacity ◽  
Comparative Investigation ◽  
Axial Stiffness ◽  
Steel Tubes ◽  
Cross Sectional ◽  
Total Cross Sectional Area ◽  
The Difference ◽  
Concrete Filled Steel Tubes ◽  
Better Than

This paper presents a comparative investigation on the load capacity of octagonal concrete filled steel tubes (CFST) with that of the commonly used circular and square CFST. Existing experimental data of octagonal CFST were collected and based on the cross-sectional properties of the existing octagonal specimens, the corresponding circular and square cross-section were generated under three different control parameters: total cross-sectional area of column, confinement ratio and axial stiffness. Those circular and square cross-sections were used in the numerical analysis of CFST to obtain the load capacity for the comparative investigation. Validated finite element models were built for the modeling of the circular and square CFST. The outcome of comparison shows that the confinement ratio is the crucial parameter to the difference of axial behaviour between octagonal and circular CFST. Under the same confinement ratio, octagonal CFST has a very close axial bearing performance to that in circular CFST and are much better than the square CFST.

The significance of warping torsion in the design of straight concrete box-girder bridges

1988 ◽  
Vol 15 (5) ◽  
pp. 879-889 ◽  
Author(s):  
Peter Waldron
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Design Stage ◽  
Assessment Procedure ◽  
Box Girder Bridges ◽  
Cross Sectional ◽  
Box Girder ◽  
Girder Bridges ◽  
Concrete Box Girder ◽  
Concrete Box Girder Bridges

Out-of-plane warping, resulting from torsional loading, is an important feature of box-girder bridges of thin-walled cross section. This may be of some consequence in girders where warping is restrained, since it may alter the level of stress both around the cross section and along the entire length of the beam. It is well known that some girders with very thin walls are not susceptible to warping, whereas others, with thicker walls, warp significantly when twisted. It is shown that the degree of warping is not governed by wall thickness alone; cross-sectional geometry, girder configuration, and loading must also be considered. The significance of these various factors in estimating the effects of warping restraint is assessed. In many cases this will permit the selection of box-girder cross sections at the conceptual design stage for which torsional warping effects are negligible. A simply supported concrete box girder is used as an example to demonstrate the importance of cross-sectional geometry, girder configuration, and loading in the assessment procedure. This is extended to the more general case of multi-span girders subjected to realistic patterns of loading. Key words: torsion, warping, box-girders, bridges, concrete, design.

Gender determination of caucasoid hair using image analysis

1993 ◽  
Vol 51 ◽  
pp. 216-217
Author(s):  
T.B. Ball ◽  
W.M. Hess
Keyword(s):  
Image Analysis ◽  
Cross Sections ◽  
Scalp Hair ◽  
The Body ◽  
Equivalent Diameter ◽  
Cross Sectional ◽  
Hair Samples ◽  
Length Width ◽  
Morphological Differences

It has been demonstrated that cross sections of bundles of hair can be effectively studied using image analysis. These studies can help to elucidate morphological differences of hair from one region of the body to another. The purpose of the present investigation was to use image analysis to determine whether morphological differences could be demonstrated between male and female human Caucasian terminal scalp hair.Hair samples were taken from the back of the head from 18 caucasoid males and 13 caucasoid females (Figs. 1-2). Bundles of 50 hairs were processed for cross-sectional examination and then analyzed using Prism Image Analysis software on a Macintosh llci computer. Twenty morphological parameters of size and shape were evaluated for each hair cross-section. The size parameters evaluated were area, convex area, perimeter, convex perimeter, length, breadth, fiber length, width, equivalent diameter, and inscribed radius. The shape parameters considered were formfactor, roundness, convexity, solidity, compactness, aspect ratio, elongation, curl, and fractal dimension.

Automated 3D measurement of fiber cross section morphology in handsheets

2012 ◽  
Vol 27 (2) ◽  
pp. 264-269 ◽  
Author(s):  
Christian Lorbach ◽  
Ulrich Hirn ◽  
Johannes Kritzinger ◽  
Wolfgang Bauer
Keyword(s):  
Image Analysis ◽  
Cross Section ◽  
Cross Sections ◽  
Image Plane ◽  
3D Measurement ◽  
Cross Sectional ◽  
Fiber Cross Section ◽  
Fiber Wall ◽  
Sectional Shape ◽  
Cross Section Geometry

Abstract We present a method for 3D measurement of fiber cross sectional morphology from handsheets. An automated procedure is used to acquire 3D datasets of fiber cross sectional images using an automated microtome and light microscopy. The fiber cross section geometry is extracted using digital image analysis. Simple sample preparation and highly automated image acquisition and image analysis are providing an efficient tool to analyze large samples. It is demonstrated that if fibers are tilted towards the image plane the images of fiber cross sections are always larger than the true fiber cross section geometry. In our analysis the tilting angles of the fibers to the image plane are measured. The resulting fiber cross sectional images are distorted to compensate the error due to fiber tilt, restoring the true fiber cross sectional shape. We use an approximated correction, the paper provides error estimates of the approximation. Measurement results for fiber wall thickness, fiber coarseness and fiber collapse are presented for one hardwood and one softwood pulp.

Evaluation of web reinforcements in prestressed concrete box girders through shear-transverse bending domains

2020 ◽  
pp. 136943322098170
Author(s):  
Michele Fabio Granata ◽  
Antonino Recupero
Keyword(s):  
Analytical Model ◽  
Prestressed Concrete ◽  
3D Analysis ◽  
Box Girders ◽  
Element Analysis ◽  
Cross Sectional ◽  
Interaction Domains ◽  
Global And Local ◽  
Resultant Forces

In concrete box girders, the amount and distribution of reinforcements in the webs have to be estimated considering the local effects due to eccentric external loads and cross-sectional distortion and not only the global effect due to the resultant forces of a longitudinal analysis: shear, torsion and bending. This work presents an analytical model that allows designers to take into account the interaction of all these effects, global and local, for the determination of the reinforcements. The model is based on the theory of stress fields and it has been compared to a 3D finite element analysis, in order to validate the interaction domains. The results show how the proposed analytical model allows an easy and reliable reinforcement evaluation, in agreement with a more refined 3D analysis but with a reduced computational burden.

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