Stabilizing the leaning tower of Pisa

In this blogpost we outline how engineers have been stabilizing the leaning tower of Pisa. We consider the history, techniques and end-result.

The leaning tower of Pisa

One of the major problems in civil engineering is getting the foundation of the building correct. Especially when the material which you are planning on building the building on consists water adhesive materials such as silt and clay. The problems with these types of characteristic materials particularly include differential settlement.

Differential settlement of the leaning tower of Pisa

Differential settlement is the procedure on which foundation weights presses water out of specific soils which adhere a large amount of water. This water is usually not easy to leave the soil of the foundation as this watery soil content, which is expressed through excess pore-volumes, contains water which when pressed over time, cause a slowly changing consolidation of the material.

The soil underneath foundations thus experience what is considered differential settlement as the water is pressed out unevenly across the foundation when pressured consistently over an excessive amount of time.

This causes the building to settle unevenly which in worst cases can form cracks along the foundation and in best situations cause lasting damages to the entire structure.

The geological composition underneath the leaning tower of Pisa

One, if not the most famous case when considering differential consolidation is the leaning tower of Pisa. The case of the leaning tower of Pisa is famous exactly because of this foundational engineering problem and have transformed from being a problem for frightening people, to be an memorable historic landmark which is cherished worldwide, see Figure 1.

The core ‘problem’ behind the leaning tower of Pisa, is the geological composition and the water tables high occurrence just below the foundation. The sandy clayey-silts which are the main source of concern is located just below the foundation. This particular composition of grain sizes is the root of the differential settlement observed.

The next layers consist of clay, followed by a small layer of intermediate sand and then once again clay. The sand is particularly problematic as water can be pressed out of the clays draining underneath water from clays to the sand content. The flow of water from the differential settlement of the leaning tower structure, allows the compression of the soil layers to easily form underneath the silty clayey top layer. Now to make things worse, the history of the leaning tower of Pisa, makes the stabilizing procedures a lot more challenging.

The leaning tower of Pisa, and a cross section of the geotechnical soil characteristics underneath the foundation. Included is the characterization of the natural material silt.
Figure 1: Left, the leaning tower of Pisa. Right, a cross-section of the geotechnical soil characteristics underneath the leaning tower of Pisa

History of the leaning tower of Pisa

The tower started out as a general massive construction planned to stand for multiple years. Construction of the main tower began in 1173 with expectations to finish later on during that century. However due to political unrest, recessions and expensive wars the construction of the tower was paused after finishing just four orders out of the originally planned eight cornices.

Related read: Effective investment strategies for climate adaptation

Financial and political unrest

This periodic influence of macroeconomic tendencies are typical of middle age construction projects where the first of the different projects are started in good periods, while most activities are cancelled or delayed during times of recessions.

The delay in construction of the at the time, Tower of Pisa, was quite significant as compared to similar buildings at the time. The delay was more than 100 years before financial and political stability was sufficient as for the funding of the building to continue onwards.

Related read: Natural materials – clay, Natural materials – sand, Natural materials – silt.

Second construction period of the tower of Pisa

The second construction period began completing three more cornices of the originally planned eight, before another interruption happened again due to political unrest and financial instabilities occurred.

Now by this time, the tower had already started tilting as the geological layers underlining the foundation had been exposed to excess pore-pressures for already 100 years more than any typical pre-consolidation theory usually encounters.

The now leaning tower of Pisa

Now the tower was leaning and construction continued until only the last order and top tower cornice needing to be finished. Work was then paused once more, due to political and financial unrest before finally the leaning tower of Pisa was finished with the tower and eight cornice completed.

It thus took almost 200 years from start to finish of the leaning tower of Pisa, a period which by many standards is quite significantly larger than any other major project under construction.

For comparison, the modern day one world trade took ‘only’ 13 years to complete but is simultaneously 104-storeys, 417 m’s high. This is in stark contrast to the 8’th orders corresponding to 57 m’s high leaning tower of Pisa.

For an example of the history of the leaning tower of Pisa, see Figure 3 from [1].

History of the leaning tower of Pisa with increasing tilt as a result
Figure 2: The history of the leaning tower of Pisa with indications of building mass and construction phases.

Modern day famous leaning tower of Pisa

The completed tower of Pisa remained standing for centuries, without any catastrophic events to occur. The result is that the tilt of the leaning tower of Pisa had reached levels which experts deemed to be critical, furthermore advanced measurement systems for monitoring the increase in the leaning tower of Pisa showed that the tilt was in matter of fact, accelerating slowly and if no measures were taken would lead to catastrophic failures within a matter of a lifetime.

Therefore it was decided to begin stabilization work in the 1990’s. At this point the the tilt was approximately 5.5 degrees, resulting in an overhang of the top cornices with about 4.1 m’s compared to the bottom of the structure, see Figure 3.

Figure 3: Cross-section of the Leaning tower of Pisa with inclination, cornices and geometric instances.

Modern day technologies have allowed for the restoration of the tilt ensuring that it is not accelerating as previously experienced. A number of different technologies were investigated. These include; placing heavy rocks on the side of the leaning tower of Pisa’s foundation, placing anchors on the leaning side and installing man pillars on the side of the leaning tower of Pisa.

The architectural challenges

It was of utmost importance not to completely fix the tilt of the tower as this was now considered a historical monument whose perseverance was valuable.

Furthermore most of the proposed solutions such as installing pillars on the side of the leaning tower and subjecting the far most side to extra load resulting in a stabilizing moment were disregarded due to the imprint on the architectural expression the building incurs in its users.

The solution to these architectural constraints was an expensive horizontal drilling action, where specific amounts of soil were excavated deep under the existing foundation in amounts carefully outlined as to provide sufficient stabilizing actions to the now already strained foundation.

Stabilization measures for the leaning tower of Pisa

Most of the proposed remedies to the tilting of the leaning tower of Pisa were tossed in the bin, as a result of the architectural expression of the leaning tower of Pisa. However some of them were utilized with great success. These measures are outlined in the following.

Horizontal directional drilling

The horizontal directional drilling equipment utilized for the procedure is outlined in figure 4-5. This type of equipment is specialized towards the excavation of small exact amounts of soils deep underneath the foundation.

Furthermore, it is also possible to see the stones and counterweights placed on the side of the foundation as a counterweight ensuring that any potential miss excavations which could resolve in destabilizing of the entire building would be counteracted by the weight of the blocks and tower combined.

The surgical procedure allows engineers and scientists to control exactly how much of the soil underneath which needed to be excavated before the tilt-acceleration is stopped.

Figure 4: Horizontal directional drilling boreholes underneath the leaning tower of Pisa. Counter weights placed away from the tilt providing a stabilizing moment. Source: Wikipedia commons.
Figure 5: Pan view of the restoration process of the leaning tower of Pisa. The view is showing the horizontal drilling action and the counterweights placed on the tower. Source: Wikipedia commons

Drainage of foundation soils

The stabilization of the leaning tower of Pisa is furthermore complicated by the excessive amount of water filled soil contents which caused the differential settlement to begin with.

The differential settlement thus occurs as a result of where the water content is pushed out from the inner core samples. This water leaks from the soil as the excess pressure from the entire building is pressing on the soil causing consolidation.

Drain pumps installed

In order to combat this phenomena, drain pumps was installed allowing the excess water contents to spill out from the soil and drained away before causing problems. The result is increased strength of the soil as water is drained causing compaction and consolidation.

The drainage pumps have been constantly pumping throughout the entire restoration process of the leaning tower of Pisa. This allowed for engineers and scientists to easily calculate and ensure safe soil consolidation while simultaneously ensuring that equipment was kept dry at all operation phases.

Cable strays for temporary stabilization

As a final installment of the renovation operation procedures ensuring that the tilting of the leaning tower of Pisa was stabilized in a sufficient manner was cables.

The cables wrap around the construction in the lower decks of the tower and was afterwards pre-strained ensuring that the Tower had gotten sufficient support ensuring that the tower was stabilized to a degree that catastrophic failure was not an issue.

Open for public usage

All the above measures were sufficient as to stabilize the tower tilt by approximately 50 cm’s from the top of the tower. The stabilizations incorporated ensured that the leaning tower of Pisa could safely be opened to the public after being closed for more than a decade in the 1990’s.

The safety of the structure was increased significantly while simultaneously ensuring that the leaning tower of Pisa remained a leaning tower. This was important as a catastrophic failure event was absolutely unacceptable by authorities while authorities simultaneously recognized the need for keeping the leaning tower of Pisa leaning.

In fact, this purposely insufficient recovery of the leaning tower of Pisa’s tilt, was incorporated with the purpose of keeping the beloved tourist attraction alive without destroying the historical value which the tower had amazed throughout its history of more than 800 years.

In conclusion

Visitors can now climb to the top of the tower and witness the beautiful views of the city of Pisa without fear or concern for their safety. The restoration project has helped to preserve the tower for future generations to enjoy, ensuring that the historical significance of this iconic structure is not lost.

Thanks to the diligent efforts of the team behind the stabilization project, the leaning tower of Pisa will continue to lean for many years to come, delighting tourists from all over the world with its fascinating story and captivating beauty.


[1] Burland, John & Jamiolkowski, Michele & Viggiani, C.. (2003). The Stabilization of the Leaning Tower of Pisa. Soils and Foundations. 43. 63-80. 10.3208/sandf.43.5_63.

Natural materials

Natural materials – silt

In this blog post we will characterize the natural material silt. We will try and answer some of the most important questions in relation to silts such as; What is silt? What is silt used for? What is the difference between silt, sand and clay? Does silt pollute water? What is siltation?

Definition of silt

Silt is a characteristic soil whose grain size lies between that of clay and sand with sizes ranging between 0.002 mm and 0.063 mm.

Related read: Soil characteristics – sand, Natural materials – clay

Silt is a detritus material meaning that it stems from weathered rock material and you can actually feel the individual particles between your fingers if rubbed gently. The physical properties of silt is hard to make general characterizations about as the individual properties depend on its ability to adhere to water and drain. An example of possible explanatory properties is the Atterberg limits.

Atterberg limits

The silty soils adherence to water makes is hard to accurately characterize. This means that the defining characteristic when it comes to soil dynamics is the ability to describe the Atterberg limits of silty soil. Atterberg limits are used to describe cohesive materials for their strength and water limit, see source.

The Atterberg limits are a simple way of describing the bearing capacities of wetted silt and clayey soils. These Atterberg limits are some of the defining limit states behind the soil characteristics and are used to accurately describe the water content and corresponding soil behavior in a simple manner.

Individual soil states

The Atterberg limits are described in four different manners called states. These states are given from silty and clayey soils and includes; Solid, Semi solid, Plastic and Liquid.

The definition of each of the subzones varies based on the type of clay and silt being investigated. Here the defining property is the ability to adhere and keep water content within the soil. Generally speaking, as the silty soils water content increases, it transforms its characteristics from that of a solid towards a liquid.

Atterberg limits visualized

The key defining characteristic behind the definitive behavior of silts and clays is their ability to keep water within the substrate. This is best illustrated from the resulting stress-strain curves usually employed when defining solid state materials bearing strengths. An illustration of the different characteristic states of the material alongside the bearing capacity of each state is outlined in Figure 1.

Illustration of the Atterberg limits where the individual soil characteristics are outlined this includes differences within the Solid Limit, Plastic Limit and Liquid Limit state space of the watery soils
Figure 1: Illustration of Atterberg limits with different strength characteristics shown versus different states of the material. This includes the stress-strain curves of the material which describe the material properties through the SL, PL and LL states

With this initial explanation of the Atterberg limits, it quickly becomes evident the importance of defining each of these limits in an accurate manner.

Thought process behind silty\clayey soils bearing capacity

To set the stage for the upcoming explanation of why these limits are important, lets try and imagine a scenario where a large infrastructure project is trying to be built.

Firstly one may investigate the initial area visually ensuring that there are no immediate obstacles needing to be removed before geotechnical investigations might be performed.

Second, a set of initial tests have examined the cross-section of the earth and found out that the initial state of the underground consists of a mixture of clay and silty soil.

Third, now one may wonder what the initial strength of such soils might be and if at all the soil exhibits sufficient capacity for bearing the load of the structure proposed for the site in question.

In conclusion, it becomes evident that the bearing capacity of silty clayey soils must be understood properly for the construction of larger infrastructures to be feasible.

As we now understand, it is important to estimate the limiting behavior of soils when subjected to loads and therefore we need to calculate the Atterberg limits. In the following sections we dive deeper into the calculation of the different types of Atterberg limits. Starting of with the liquid limit, LL.

The Casagrande cup experiment

The Casagrande cup experiment is used for the determination of the soil water content based on a standardized number of blows until a small valley created through use of specialized instruments collapses. See Figure 2 for an illustration of the equipment and resulting collapse of the valley.

The Casagrande test experiment illustration of the equipment utilized alongside with an explanatory figure of a silty soil sample.
Figure 2: Casagrande cup filled with substrate. Top left: valley and filled cup before number of blows. Bottom left: Collapsed valley after x number of blows. Right: Illustration describing the specialized equipment used for creating the valley and material used as shock absorption.

When the valley starts to fall together the number of blows is numbered on a piece of paper. The soil sample is then weighed and dried with the resulting weight before and after measured carefully. This way you can determine the number of blows before failure mechanisms of the substrate are activated as a function of the water content of the sample.

A relationship between the number of blows and the water content can then be drawn and theoretical distributions for the soil strength can be inferred through careful regression techniques. An example of a given relationship between water content and number of blows is outlined in Figure 3. The predetermined liquid limit is theoretically defined for 25 number of blows to the sample.

Describing the water content and corresponding number of blows in the Casagrande test for identification of the liquified limit of the soil sample.
Figure 3: Water content versus number of blows within the Casagrande cup experiment before the collapse of the shear walls. The liquid limit of the Casagrande experiment corresponds to the straight line interception at 25 blows.

The liquid limit described by this test allows for an easy and fast interpretation of the liquid limit of silty clayey soils.

Now in order to try and estimate the plastic limit of the soil we need another test measure technique called the rolling test.

Rolling tests determining plasticity level

In order to determine the plastic limit of the soil, the limit where constant stress cause constant strain, we need to perform a rolling test on a sample of the substrate.

The methodology of performing a rolling test is in short to roll out a specific sample of the soil under assumptions of constant stress and cross section until the water content start to crack. When cracking is initiated the sample is quickly weighed before being dried out in the lab heaters for 24 hours.

Soil sample roll speed

When rolling the soil sample out you are actually drying out the sample therefore it is important to realize that the speed at which you are rolling out the sample influences the drying rate and correspondingly can result in errors as the sample is considered to contain a constant water content.

Faster speeds and pressure on the silty soil sample will cause inaccurate measurements of the water contents due to the pressure distribution on the soil pushing out water from underneath the soil sample.

A characterization technique for the natural material silt.
Figure 4: Example of a rolled silt soil experiment. The silty soil is observed through use of the cracked and jagged sample

However, rolling out the soil sample slowly is neither a good option as the contents of the water sample is likewise going to dry out before being able to accurately predict the water contents.

A perfect roll out speed is necessary for the plastic limit of the soil to be accurately described. This speed depends and varies individually from the different soil samples and thus expert engineering judgement is needed for determination of the plastic limits.

Differentiating clay from silt

When trying to investigate soil properties and before determining and characterizing the difference qualitative parameters of the soil sample it is important to consider the distinctive behavior’s separating silt from clay. The distinction is easily made through use of two different test techniques. Firstly the ‘Elephant’ test technique is easily utilized

Elephant test technique

The elephant test technique for distinguishing soil behavior’s is quickly and accurately utilized even without expensive field laboratory equipment. The distinctive test is performed by creating an elephant like trunk shape of a small soil sample which is approximately 3 mm thick in shape.

The shape of the constructed elephant trunk is then examined and seen whether or not it is able to withstand the force underneath its own gravity. If the trunk easily upheld its own shape under its own weight, then the soil sample is considered to be clay.

However if the soil sample cannot easily withstand the force of gravity with deformed shapes and cracks on the surface then the soil sample is considered silt. This is an easy and inexpensive way of making sure that the soil sample in question is actually silt and not clay and visa versa.

Another commonly used methodology is to create a bended U-shaped sausage which is then utilized to check for cracks in a similar manner as the elephant. These inexpensive ways of determining whether or not a soil sample is consisting of clay or silt is invaluable.

With this being said, there also exist other methodologies to easily investigate whether a soil sample is clay or silt one of these is called a sedimentation test.

Sedimentation testing

The sedimentation test is a technique similar to that of the elephant test in that this specific version is likewise meant as an example to try and differentiate the soil sample into clay and silt respectively. The clay particles when settling in a tube will create a mixture of solid particles and liquids called a suspension while a silt sample will create a coarser sample.

Suspension definition and behavior

A suspension is particular interesting when trying to investigate the hydrodynamic properties of a fluid and when trying to investigate eco-systemic impacts of large infrastructure projects.

The ecosystem can easily be affected by suspensions in the sense that endangered species are affected by floating clay particles where gills of fish are clotted and marine fauna such as eelgrass are threatened by sedimentation layers stealing available sunlight.

The problems also arrives when considering the time spent on the settling particle velocities which for a given suspension can be extremely small, allowing individual particles to easily stay in the suspended water column for extended periods of time before it will be able to settle on the ground surface.

For clay the particles can stay in suspension for hours even days without settling in still water due to the water undulations within the water column causing the fine material to keep sculpting around.

Settling behavior of silt

The difference in settling between clay and silt is easily measured when conducting sedimentation experiments. As explained, the clay settling velocities are small allowing for the suspension to keep particles in the water column for extended periods of time corresponding to days.

For silt the suspension will fall out of the water column much faster than clays and thus when investigating soil samples and characterizing the sample into clay and silt, measuring the settling time and velocities would allow you to easily distinguish the soil sample into clay and silt.

The silts settling velocity is much larger than clay due to mainly two phenomena, the particle sizes of silt are an order of magnitude larger and flocculation effects are often quite significant for silty materials. The flocculation is when particles of different sizes clump together during settling resulting in increasing settling velocity of the entire joint lump of particles compared to the individual ones.

This particulate behavior leads to a common phenomena called siltation.


Siltation is a phenomena common in river -streams and -mouths as a result of excavating, extreme rainfall events or pollution. The siltation of river streams poses environmental dangers to ecosystems as the consequent sedimentation strangles bottom feeding and living creatures, while simultaneously damaging eggs and larvae exposed to silted environments.

Some common example of siltation events occur during marine dredging where silted material is transported upwards in the water column. The upward momentum allows whirling of particles up into the undisturbed water column causing the individual particles to be transported large distances and spread out over potentially endangered areas.

Another example of siltation is during extreme rainfall events where soil banks are eroded away due to increased water volumes causing silt and clay rich banks to be eroded and washed into the water column.

When transported downstream and before settling down into more calmer waters this siltation of water streams can cause suffocation of fish and degradation of wildlife. It is therefore considered an environmental disaster when rivers are exposed to siltation events.


Earthquake proofing buildings

In this blogpost we will try and answer some questions in relation to earthquake proofing buildings using different materials and tools.

Earthquakes in short

Earthquakes are disastrous events influencing people, infrastructure and houses. The most prone areas to earthquakes are lie at fault lines where epicenters of earthquakes usually happen, see Figure 1 and 2 for epicenters and tectonic plates respectively.

Earthquake epicenter distributions across the earth.
Figure 1: Location of earthquakes epicenters across the globe. This distribution of epicenters supports the hypothesis of tectonic plates present across the globe.
Illustration over Tectonic plates and their different types of movements including subduction, spreading and tearing
Figure 2: Location of the tectonic plates across the globe. Illustration of the different types of plate tectonics including subduction, lateral sliding and spreading events.

The exact locations of when and where earthquakes will happen varies as the nature of these events is chaotic. However they usually follow patterns as outlined by the fault lines where tectonic plates meet and exchange information. In addition, the frequency of occurrence alongside with magnitude of earthquakes are completely unpredictable in nature.

This fundamental description of earthquakes causes problems for engineers and scientists alike. Engineers are faced with the challenge of accurately creating safe and sound buildings able to withstand the next earthquake, while scientists are faced with the problems of understanding the different phenomena which are chaotic in nature.

Related read: Top ten misconceptions about earthquakes, effective investment strategies for climate adaptation.

When engineers are facing the problems of designing buildings in earthquake prone areas It is often necessary to find solutions for the moving and differential settlement for which buildings are subjected to.

Earthquake proofing buildings – blocks

One solution to earthquake proofing buildings is for the building to move together with the earth during the earthquake. In order for the building to easily move together with the earthquake the foundation of the building needs to be placed on elastic blocks. See Figure 3 for an illustration.

The concept of spring-mats for earthquake proofing buildings.
Figure 3: Illustration of the spring mats utilized for stabilizing the foundations beneath the floor of buildings. Illustration is not to scale.

The movement blocks allow the foundation to absorb some of the shearing movements caused by the earthquakes surface waves, the so-called Rayleigh and Love waves. This allows them to withstand stronger more devastating movements when compared to houses without mats.

Related read: earthquake epicenters

Earthquake proofing buildings – tuned mass damper

Another example of a way to earthquake proof buildings and larger structures such as bridges, towers and walkways is through the use of a tuned mass damper.

The tuned mass damper is a special type of damper designed specifically to the building in question. It works by adding a suspended mass into towers or structures. The suspended mass works by shifting the buildings eigenfrequency sufficiently higher than before such that earthquake vibrations are damped out before destroying the building. The dampening works by absorbing the deformation inside the tuned mass damper. For an illustration of the concept of a tuned mass damper see Figure 4 and Gallery 1 for real life counterparts.

The concept of a tuned-mass-damper for earthquake proofing buildings.
Figure 4: Illustration of a tuned mass damper located inside the top of a tall building. The illustration is not to scale.

As we can see the different types of tuned mass dampers varies in shape, form and size from the relatively small discrete ones underneath walkways till the large heavy ones inside the Taipei 101 and Shanghai towers.

Earthquake destruction in Turkey-Syria

Recently the Turkish earthquake Kahramanmaras lead to a massive destruction of buildings, infrastructure and railroads alike. The destruction of buildings was massive as can be seen when comparing the a before and after image from Kahramanmaras, see Gallery 2.

The destruction led to massive amounts of death and homelessness in the thousands of numbers, see source. This destruction is terrible for the population of Turkey and Syria where the death tool is immense alongside with the cold winter coming showing degrees below freezing during the cold nights.

What are the best materials for earthquake-proof buildings

The best materials for earthquake proofing buildings are steel and elastic materials. The strength of steel allow it to absorb stresses from the earth foundation strains.

Steel as a building material

Furthermore the elasticity of steel is sufficient for deformations to remain elastic as compared to plastic. Elastic deformations are important as the destructive forces usually occur due to permanent shifting of loads during the plastic deformation of bearing members of the structure.

Since steel is an exceptionally strong material with large elastic and plastic bearing capacities it makes it ideal as a construction material for earthquake prone buildings. For an example curve of the strength of steel see Figure 5 for an example of a steel loading curve.

Stress-strain curve for steel showcasing the elastic and plastic parts of the curve.
Figure 5: Stress-strain illustration of typical steel with indications of elastic (linear deformation) and plastic deformations.

We can see that the strength of steel during the elastic part of the curve is linearly proportional to the displacement, meaning that we can load up and down the displacement curve without loss of strength.

This curve is representative of all axial strains meaning that steel is isotopic and thus able to withstand forces with equal strength in all directions.

Wood as a building material

Unlike steel there is wood. Wood is a natural material whose properties depend on the type of wood, the age and location to name a few. In fact, wood is not isotopic since fibers are growing upwards from the stem.

The mechanical properties of wood therefore varies from tree to tree and depending on the force direction of loading including axial and torsional directions. An example of a typical axial stress-strain loading curve is shown in Figure 6.

Stress-strain curve of wood showcasing the elastic and plastic parts of the strength curves
Figure 6: Stress-strain relationship for the axial loading of wood. Indications of plastic regions have been made. Reproduced from source.

As we can see when comparing the curve from wood with the curve from steel we can see that the elastic region is followed by a small plastic period with increased strength for steel while the wood curve is flattening out directly after yield stresses are observed.

In both cases the axial strength increases in a short period before failure for steel, which is the hardening period, while tree follows densification before failure.

Comparing wood vs steel

For steel the hardening period is followed by increasingly plastic deformation and loss of material strength throughout the necking period. This period allows buildings to deform providing a warning sign before failure. The behavior of deformation before failure is known as ductility and is a particular sought after characteristic for building materials.

For wood the linear elastic period of deformation in the axial direction is followed by plastic continual deformation. This means that the wood will compress without gaining strength up until the point of densification. Densification is the happening where tree fibers are compressing increasing the capacity of the wood before failure occurs due to cracking fibers.

With these considerations when trying to earthquake proof buildings it is important to make the bearing elements strong and elastic. For this purpose steel is an excellent material.

Building earthquake-proof buildings

In conclusion utilizing different measures such as tuned mass dampers or spring mats increases the foundation bearing capacity in regards of vibrational stressors from earthquakes.

For the building materials it should be performed in steel for the load bearing parts of the structure ensuring that maximum elasticity and strength against materials is achieved.

Steel unlike wood, is isotopic meaning that shear forces from earthquakes are easily absorbed in a manner similar to axial compression while wooden structures will act differently depending on the mode of deformation and earthquake surface waves.


Stress-strain curve for wood

Number of casualties in earthquake Turkey-Syria –