Sunday, April 14, 2013

Improved model

Engineers make models to represent

The things they build which are meant

To help them more fully comprehend

How things will strain, stress, break or bend.

In the engineer’s model of tradition
A masonry arch is viewed in partition
A cross-sectional view works just fine
To show stress as a curved thrust line.

A catenary line like a hanging chain
Turned upside down in your brain
Represents the lines of thrust
In the arch’s thickness it must-

Be constrained within that wall
Or a hinge will form and it will fall
This is the old traditional way:
To show an arch with this display.

But now there is a newer block
Whose edges each interlock
Hinges will no longer suffice
To show how well and truly nice

And stronger too these arches are
Conjugate shearing is the star
Of this newer model which is much better
Made of improved block that lock together

They do not hinge or buckle wide
Against each other they simply slide
And if you get this simple point
It is a better masonry joint.


No comments:

Post a Comment