History of structural engineering

Throughout ancient and medieval history most architectural design and construction was carried out by artisans, such as stone masons and carpenters, rising to the role of master builder.

It remained the largest man-made structure for millennia and was considered an unsurpassed feat in architecture until the 19th century AD.

[citation needed] The understanding of the physical laws that underpin structural engineering in the Western world dates back to the 3rd century BC, when Archimedes published his work On the Equilibrium of Planes in two volumes, in which he sets out the Law of the Lever, stating: Equal weights at equal distances are in equilibrium, and equal weights at unequal distances are not in equilibrium but incline towards the weight which is at the greater distance.Archimedes used the principles derived to calculate the areas and centers of gravity of various geometric figures including triangles, paraboloids, and hemispheres.

Their methods are recorded by Vitruvius in his De Architectura written in 25 BC, a manual of civil and structural engineering with extensive sections on materials and machines used in construction.

During the High Middle Ages (11th to 14th centuries) builders were able to balance the side thrust of vaults with that of flying buttresses and side vaults, to build tall spacious structures, some of which were built entirely of stone (with iron pins only securing the ends of stones) and have lasted for centuries.

It was the first establishment of a scientific approach to structural engineering, including the first attempts to develop a theory for beams.

[10] Also in the 17th century, Sir Isaac Newton and Gottfried Leibniz both independently developed the Fundamental theorem of calculus, providing one of the most important mathematical tools in engineering.

Specifically, he developed the Euler–Bernoulli beam equation with Daniel Bernoulli (1700–1782) circa 1750 - the fundamental theory underlying most structural engineering design.

[13] Throughout the late 19th and early 20th centuries, materials science and structural analysis underwent development at a tremendous pace.

[16] Towards the end of the 19th century, in 1873, Carlo Alberto Castigliano presented his dissertation "Intorno ai sistemi elastici", which contains his theorem for computing displacement as partial derivative of the strain energy.

Ditherington Flax Mill in Shrewsbury, designed by Charles Bage, was the first building in the world with an interior iron frame.

This was later improved upon with the construction of Belper North Mill, a collaboration between Strutt and Bage, which by using a full cast iron frame represented the world's first "fire proofed" building.

Wilhelm Ritter formulated the truss theory for the shear design of reinforced concrete beams in 1899, and Emil Mörsch improved this in 1902.

Freyssinet constructed an experimental prestressed arch in 1908 and later used the technology in a limited form in the Plougastel Bridge in France in 1930.

The possibility of creating structures with complex geometries, beyond analysis by hand calculation methods, first arose in 1941 when Alexander Hrennikoff submitted his D.Sc thesis at MIT on the topic of discretization of plane elasticity problems using a lattice framework.

This led in 1956 to the publication by J. Turner, R. W. Clough, H. C. Martin, and L. J. Topp's of a paper on the "Stiffness and Deflection of Complex Structures".

Where larger openings like garage doors are required, the tube frame must be interrupted, with transfer girders used to maintain structural integrity.

This allowed for a reduced need for interior columns thus creating more floor space, and can be seen in the John Hancock Center.

Later buildings with sky lobbies include the World Trade Center, Petronas Twin Towers and Taipei 101.

In 1987 Jörg Schlaich and Kurt Schafer published the culmination of almost ten years of work on the strut and tie method for concrete analysis - a tool to design structures with discontinuities such as corners and joints, providing another powerful tool for the analysis of complex concrete geometries.