Weighted catenary

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A hanging chain is a regular catenary -- and is not weighted. Kette Kettenkurve Catenary 2008 PD.JPG
A hanging chain is a regular catenary and is not weighted.

A weighted catenary is a catenary curve, but of a special form. A "regular" catenary has the equation

Contents

for a given value of a. A weighted catenary has the equation

and now two constants enter: a and b.

Significance

A catenary arch has a uniform thickness. However, if

  1. the arch is not of uniform thickness, [1]
  2. the arch supports more than its own weight, [2]
  3. or if gravity varies, [3]

it becomes more complex. A weighted catenary is needed.

The aspect ratio of a weighted catenary (or other curve) describes a rectangular frame containing the selected fragment of the curve theoretically continuing to the infinity. [4] [5]

The St. Louis arch: thick at the bottom, thin at the top. St Louis night expblend cropped.jpg
The St. Louis arch: thick at the bottom, thin at the top.

Examples

The Gateway Arch in the American city of St. Louis (Missouri) is the most famous example of a weighted catenary.

Simple suspension bridges use weighted catenaries. [5]

Related Research Articles

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In physics and geometry, a catenary is the curve that an idealized hanging chain or cable assumes under its own weight when supported only at its ends.

Hyperbola Plane curve: conic section

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Dupin cyclide

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Involute Mathematical curve constructed from another curve

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Tractrix Curve traced by a point pulled through a segment of fixed length by a point moving on a line

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Evolute

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Arc length Distance along a curve

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Elliptic coordinate system

In geometry, the elliptic coordinate system is a two-dimensional orthogonal coordinate system in which the coordinate lines are confocal ellipses and hyperbolae. The two foci and are generally taken to be fixed at and , respectively, on the -axis of the Cartesian coordinate system.

Bipolar cylindrical coordinates

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Elliptic cylindrical coordinates

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Inverse curve

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Parabolic arch Type of arch shape

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Kepler orbit

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Conic section Curve obtained by intersecting a cone and a plane

In mathematics, a conic section is a curve obtained as the intersection of the surface of a cone with a plane. The three types of conic section are the hyperbola, the parabola, and the ellipse; the circle is a special case of the ellipse, though historically it was sometimes called a fourth type. The ancient Greek mathematicians studied conic sections, culminating around 200 BC with Apollonius of Perga's systematic work on their properties.

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Orthoptic (geometry)

In the geometry of curves, an orthoptic is the set of points for which two tangents of a given curve meet at a right angle.

Confocal conic sections

In geometry, two conic sections are called confocal, if they have the same foci. Because ellipses and hyperbolas possess two foci, there are confocal ellipses, confocal hyperbolas and confocal mixtures of ellipses and hyperbolas. In the mixture of confocal ellipses and hyperbolas, any ellipse intersects any hyperbola orthogonally. Parabolas possess only one focus, so, by convention, confocal parabolas have the same focus and the same axis of symmetry. Consequently, any point not on the axis of symmetry lies on two confocal parabolas which intersect orthogonally.

References

  1. Robert Osserman (February 2010). "Mathematics of the Gateway Arch". Notices of the AMS.Missing or empty |url= (help)
  2. Re-review: Catenary and Parabola: Re-review: Catenary and Parabola, accessdate: April 13, 2017
  3. MathOverflow: classical mechanics - Catenary curve under non-uniform gravitational field - MathOverflow, accessdate: April 13, 2017
  4. Definition from WhatIs.com: What is aspect ratio? - Definition from WhatIs.com, accessdate: April 13, 2017
  5. 1 2 Robert Osserman (2010). "How the Gateway Arch Got its Shape" (PDF). Nexus Network Journal. Retrieved 13 April 2017.

On the Gateway arch

Commons