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Menegon Alexandru-Bogdan

Inginerie Geotehnica an 1

Constructions of the Colosseum Theatre at Leptis Magna

The constructions of the Flavian amphitheatre or Colosseum, and the Theatre at

Leptis Magna both demonstrate the importance of Roman construction methods andmaterials used, to accommodate for the use of each building, as is true for the shape,

layout and architectural features of both buildings. We see that these features of the buildings overlap and interrelate to achieve success in all areas of usage, showing both

the magnificence in each building as well as in some cases, Roman propaganda.The materials used in each building have had a strong influence in the usage of 

them. The Colosseum demonstrates the use of lighter building materials in order tosupport the weight of the construction, as if materials were too heavy, the building

would not be able to stand, particularly in the free standing tiered seating. Travertinestone, or limestone, is the main material used in the building of the Colosseum, as well

as opus cementicium and brick as these are lighter than other materials and are resistant,

an important feature in order to allow the Colosseum to be a success, and one which has

allowed it to stand for so many years. The main body of the construction, and thecolumns and paved area around the Colosseum are made from travertine stone; however 

the top level was made from wood in order to reduce the weight. Most of theColosseum was paved in marble, used for its aesthetic qualities. Because it is a heavier 

stone, it was simply veneered over the other stonework to allow less weight, and thiswas used on top cover most of the building including the seating. The use of marble

also demonstrated propaganda to the people of Rome, as by using the handsome stoneon public seating showed the crowds the goodness of the Emperor towards his people.

The use of a wooden arena was particularly successful as it allowed the floor to beremoved for ―sea battles‖, in which the arena was flooded with water and gladiatorial

 boats were used for fighting, and then could be put back for the land based activities.The theatre of Leptis Magna is constructed mostly from grey limestone, yet fairly plain

stone but allowing a strong foundation for the theatre. Cipollino marble is again used in

the theatre for its aesthetic qualities. The first tier of the cave is made using marble, because this is where the authority of the city, and most important theatre goers sat aswell as thrones which the attendants sat on in this part of the seating also constructed

from marble, to demonstrate their importance.The construction methods of the Colosseum relate to the materials used also. The

use of arches in the building is the most important construction method of theColosseum. The building is supported by the many arches through it, as these allow the

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 building to create wedges, which in turn allow the oval shape of the amphitheatre. The

use of arches reduces the weight of the building also, as it allows the reduction of materials, which of course also relates to the materials chosen to make these, as

together, the weight is reduced to allow the free standing of the building. The arches

therefore also allow the tiered seating to be supported, and along with the 37 degreeangle of the seating aids in allowing the building to be free standing. The barrel vault

 passageways of the arches are also successful in allowing the easy access for the crowdsin filling and emptying the theatre, as there are so many passageways.

History of the civil engineering profession

Engineering has been an aspect of life since the beginnings of human existence.Civil engineering might be considered properly commencing between 4000 and 2000BC in Ancient Egypt and Mesopotamia when humans started to abandon a nomadic 

existence, thus causing a need for the construction of shelter. During this time,transportation  became increasingly important leading to the development of the wheel 

and sailing. The construction of  Pyramids in Egypt (circa 2700-2500 BC) might be

considered the first instances of large structure constructions. Other ancient historic

civil engineering constructions include the Parthenon  by Iktinos in Ancient Greece (447-438 BC), the Appian Way  by Roman engineers (c. 312 BC), and the Great Wall of 

China  by General Meng T'ien under orders from Ch'in Emperor  Shih Huang Ti (c. 220

BC). The Romans developed civil structures throughout their empire, includingespecially aqueducts, insulae, harbours,  bridges, dams and roads.

Until modern times there was no clear distinction between civil engineering and

architecture, and the term engineer and architect were mainly geographical variationsreferring to the same person, often used interchangeably. In the 18th century, the term

civil engineering began to be used to distinguish it from military engineering.The first self-proclaimed civil engineer was John Smeaton who constructed the

Eddystone Lighthouse. In 1771 Smeaton and some of his colleagues formed theSmeatonian Society of Civil Engineers, a group of leaders of the profession who met

informally over dinner. Though there was evidence of some technical meetings, it waslittle more than a social society.

In 1818 the Institution of Civil Engineers was founded in London, and in 1820the eminent engineer  Thomas Telford  became its first president. The institution

received a Royal Charter in 1828, formally recognising civil engineering as a profession. Its charter defined civil engineering as the art of directing the great sources

of power in nature for the use and convenience of man, as the means of production and

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of traffic in states, both for external and internal trade, as applied in the construction of 

roads, bridges, aqueducts, canals, river navigation and docks for internal intercourse andexchange, and in the construction of ports, harbours, moles, breakwaters and

lighthouses, and in the art of navigation by artificial power for the purposes of 

commerce, and in the construction and application of machinery, and in the drainage of cities and towns.

The first private college to teach Civil Engineering in the United States was Norwich University founded in 1819 by Captain Alden Partridge. The first degree in

Civil Engineering in the United States was awarded by Rensselaer Polytechnic Institute in 1835. The first such degree to be awarded to a woman was granted by Cornell

University to  Nora Stanton Blatch in 1905.

History of the science of civil engineering

Civil engineering is the application of physical and scientific principles, and its

history is intricately linked to advances in understanding of   physics and mathematics throughout history. Because civil engineering is a wide ranging profession, including

several separate specialized sub-disciplines, its history is linked to knowledge of 

structures, materials science, geography, geology, soils, hydrology, environment, mechanics and other fields.

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 . Knowledge was retained in guilds and seldom supplanted byadvances. Structures, roads and infrastructure that existed were repetitive, and increases

in scale were incremental.One of the earliest examples of a scientific approach to physical and

mathematical problems applicable to civil engineering is the work of  Archimedes in the3rd century BC, including Archimedes Principle, which underpins our understanding of 

 buoyancy, and practical solutions. Brahmagupta, an Indian mathematician, usedarithmetic in the 7th century AD, based on Hindu-Arabic numerals, for excavation

(volume) computations.

Romanian architecture

Pre-Modern styles

During the middle ages in Romania there were two types of construction thatdeveloped in parallel and different in point of both materials and technique. The first is

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the popular architecture, whose most spectacular achievements were the wooden

churches, especially those in the villages of  Maramureş, Banat and Apuseni Mountains, where the tradition is still carried out today. In Maramureş, in Surdeşti village, the 54 m

high church tower built during 1721 – 1724 is among the highest of this kind in Europe.

The second comprises mainly of monasteries, as well as princely seats or boyar mansions. Unfortunatelly, most of the old lay edifices were destroyed by time, wars,

earthquakes and fires.In mediaeval architecture, influences of Western trends can be traced, to a greater 

or lesser extent, in all the three lands inhabited by Romanians. Such influences arestronger in Transylvania, and weaker in Moldavia, in forms absorbed by local and

Byzantine tradition. In Wallachia, Western elements in architecture were even fewer;

there, from the 14th century architecture was based on the local adaptation of theByzantine model (the Princely Church in Curtea de Arges and the Cozia Monastery).

There are monuments significant for the Transylvanian Gothic style  preserved to

this day, in spite of all alterations, such as the Black Church in Braşov (14th – 15th c.)and a number of other  cathedrals, as well as the Bran Castle in Braşov County (14th c.),the Hunyades Castle in Hunedoara (15th c.).

Transylvania also developed fortified towns extensively during the Middle Ages;

their urban growth respected principles of functionality (the usual pattern is a centralmarket place with a church, narrow streets with sides linked here and there by

archways): the cities of  Sighişoara, Sibiu and Braşov are remarkable examples in that

sense. Building greatly developed in Moldavia, too. A great number of fortresses were built or rebuilt during the reign of Moldavia's greatest prince, Stephen the Great (1457 – 

1504). Suceava,  Neamţ, Hotin, Soroca and others were raised and successfully

withstood the sieges laid in the course of time by Sultan Mehmet II, the conqueror of Constantinople, by the kings of Poland and Hungary.

It was during his time that the Moldavian style, of great originality and stylisticunity, developed, by blending Gothic elements with the Byzantine structure specific to

the churches. Among such constructions, the monumental church of the  Neamţ

Monastery served, for more than a century, as a model for  Moldavian churches and

monasteries. The style was continued in the 16th c., during the rule of Stephen theGreat's son, Petru Rareş (1527 – 1538, 1541 – 1546). The main innovation was the porch

and the out wall paintings (the churches of  Voroneţ, Suceviţa, Moldoviţa monasteries).

These churches of Northern Moldavia have become famous worldwide, due to the beauty of their painted elegant shapes that can be seen from afar.

The 17th century, the zenith of the pre-modern Romanian civilisation, brought

about a more significant development of outstanding lay constructions (elegant boyardmansions or sumptuous princely palaces in Moldavia and Wallachia, Renaissance-style

lordly castles in Transylvania), as well as the expansion of great monasteries. The latter were endowed with schools, art workshops, printing presses, and they were significant

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cultural centres. To this period belongs the church of the Trei Ierarhi Monastery in Iaşi, 

raised in 1635 – 1639, a unique monument due to its lavish decoration with carvedgeometric motifs, coloured in lapis lazuli and golden foil, all over the facades. The

architectural style developed in Wallachia, especially under the reigns of  Matei Basarab 

(1632 – 1654) and Constantin Brâncoveanu (1688 – 1714), is of a remarkable stylisticunity. The Brancovan style is characterized by integration of  Baroque and Oriental 

features into the local tradition. Some examples are the Hurezi Monastery in Oltenia or the princely palace of  Mogoşoaia, both of which are lavishly decorated, with beautiful

stone carvings, stucco work and paintings.The 18th century (the Phanariot rule) brought to Wallachia and Moldavia

elements of  Oriental influence in urban civil architecture, where the number of religious

constructions decreased relatively. In Transylvania, the Baroque dominated bothreligious (the Roman Catholic churches in Timisoara and Oradea) and lay architecture(Banffy Palace in Cluj and Brukenthal Palace in Sibiu).

Modern Styles

In the first half of the 19th century, urban life grew considerably and there was a

Western-type modernisation policy, due to which the architecture of the Romanian

lands became a combination of Romantic and Neo-Classical elements. In the secondhalf of the century a national tendency developed, to use to a great extent elements and

forms of the traditional local architecture. Ion Mincu (1852 – 1912) was founder of both

trends and of the Romanian school of architecture. His works, the Lahovary House or the Central Girls School in Bucharest, are among the most prominent achievements of this movement. It is due to an opposite trend that they designed houses and

administrative buildings in the spirit of French eclecticism (the Justice Palace, theCentral Post Office) or by adapting classicism (the buildings that now hosts the Houseof the Men of Science, or the Cantacuzino Palace in Bucharest).

Steel

Steel is an alloy consisting mostly of  iron, with a carbon content between 0.2%

and 2.1% by weight, depending on the grade. Carbon is the most cost-effective alloying

material for iron, but various other alloying elements are used such as manganese, chromium, vanadium, and tungsten. Carbon and other elements act as a hardening

agent, preventing dislocations in the iron atom crystal lattice from sliding past one

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another. Varying the amount of alloying elements and form of their presence in the steel

(solute elements, precipitated phase) controls qualities such as the hardness, ductility, and tensile strength of the resulting steel. Steel with increased carbon content can be

made harder and stronger than iron, but is also less ductile. 

Alloys with a higher carbon content are known as cast iron  because of their lower melting point and castability Steel is also distinguished from wrought iron, which can

contain a small amount of carbon, but it is included in the form of  slag inclusions. Twodistinguishing factors are steel's increased rust-resistance and better  weldability. 

Though steel had been produced by various inefficient methods long before theRenaissance, its use became more common after more efficient production methods

were devised in the 17th century. With the invention of the Bessemer process in the

mid-19th century, steel became a relatively inexpensive mass-produced material.Further refinements in the process, such as  basic oxygen steelmaking, further lowered

the cost of production while increasing the quality of the metal. Today, steel is one of 

the most common materials in the world and is a major component in buildings,infrastructure, tools, ships, automobiles, machines, and appliances. Modern steel isgenerally identified by various grades of steel defined by various standards

organizations. 

Material properties

Iron, like most metals, is found in the Earth's crust only in the form of an ore,

combined with other elements such as oxygen or  sulfur . Typical iron-containingminerals include Fe2O3 — the form of  iron oxide found as the mineral hematite, and

FeS2 —  pyrite (fool's gold). Iron is extracted from ore  by removing oxygen andcombining the ore with a preferred chemical partner such as carbon. This process,

known as smelting, was first applied to metals with lower  melting  points, such as tin, which melts at approximately 250 °C (482 °F) and copper , which melts at

approximately 1,000 °C (1,830 °F). In comparison, cast iron melts at approximately1,370 °C (2,500 °F). All of these temperatures could be reached with ancient methods

that have been used since the Bronze Age. Since the oxidation rate itself increases

rapidly beyond 800 °C, it is important that smelting take place in a low-oxygenenvironment. Unlike copper and tin, liquid iron dissolves carbon quite readily. Smelting

results in an alloy ( pig iron) containing too much carbon to be called steel. The excesscarbon and other impurities are removed in a subsequent step.

Other materials are often added to the iron/carbon mixture to produce steel withdesired properties.  Nickel and manganese in steel add to its tensile strength and make

austenite more chemically stable, chromium increases hardness and melting

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temperature, and vanadium also increases hardness while reducing the effects of  metal

fatigue. To prevent corrosion, at least 11% chromium is added to steel so that a hardoxide forms on the metal surface; this is known as stainless steel. Tungsten interferes

with the formation of cementite, allowing martensite to form with slower quench rates,

resulting in high speed steel. On the other hand, sulfur , nitrogen, and  phosphorus makesteel more brittle, so these commonly found elements must be removed from the ore

during processing.The density of steel varies based on the alloying constituents, but usually ranges

 between 7.75 and 8.05 g/cm3 (0.280 – 0.291 lb/in3).Even in the narrow range of concentrations which make up steel, mixtures of 

carbon and iron can form a number of different structures, with very different

 properties. Understanding such properties is essential to making quality steel. At roomtemperature, the most stable form of iron is the  body-centered cubic (BCC) structure α-

ferrite. It is a fairly soft metallic material that can dissolve only a small concentration of 

carbon, no more than 0.021 wt% at 723 °C (1,333 °F), and only 0.005% at 0 °C (32 °F).If the steel contains more than 0.021% carbon then it transforms into a face-centeredcubic (FCC) structure, called austenite or γ-iron. It is also soft and metallic but can

dissolve considerably more carbon, as much as 2.1% carbon at 1,148 °C (2,098 °F)),

which reflects the upper carbon content of steel.When steels with less than 0.8% carbon, known as a hypoeutectoid steel, are

cooled from an austenitic phase the mixture attempts to revert to the ferrite phase,

resulting in an excess of carbon. One way for carbon to leave the austenite is for cementite to  precipitate out of the mix, leaving behind iron that is pure enough to take

the form of ferrite, resulting in a cementite-ferrite mixture. Cementite is a hard and

 brittle intermetallic compound with the chemical formula of Fe3C. At the eutectoid, 0.8% carbon, the cooled structure takes the form of   pearlite, named after its

resemblance to mother of pearl. For steels that have more than 0.8% carbon the cooledstructure takes the form of pearlite and cementite.

Perhaps the most important  polymorphic form is martensite, a metastable phase

which is significantly stronger than other steel phases. When the steel is in an austenitic

 phase and then quenched it forms into martensite, because the atoms "freeze" in placewhen the cell structure changes from FCC to BCC. Depending on the carbon content

the martensitic phase takes different forms. Below approximately 0.2% carbon it takes

an α ferrite BCC crystal form, but higher carbon contents take a  body-centeredtetragonal (BCT) structure. There is no thermal activation energy for the transformation

from austenite to martensite. Moreover, there is no compositional change so the atoms

generally retain their same neighbors.Martensite has a lower density than austenite does, so that transformation

 between them results in a change of volume. In this case, expansion occurs. Internalstresses from this expansion generally take the form of  compression on the crystals of 

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martensite and tension on the remaining ferrite, with a fair amount of  shear  on both

constituents. If quenching is done improperly, the internal stresses can cause a part toshatter as it cools. At the very least, they cause internal work hardening and other 

microscopic imperfections. It is common for quench cracks to form when water 

quenched, although they may not always be visible.