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Structure Collapse - Science topic

Failure in built environment with loss of functional integrity.
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Since 1987 we have been trying to solve a sustainability issue like the eco-economic development issue through sustainable development means, a theory-practice inconsistency, so not surprise the social and environmental sustainability issues the Brundtland Commission highlighted then to be addressed are in worse state today,,,,Pollution still increasing and the sustainability problem more acute.
If the price distortions embedded in Adam Smith's traditional market model thinking are not addressed head on, the Thomas Kuhn.s paradigm evolution loop suggest that the worsening of the environmental abnormalities embedded fully in the traditional market thinking and partially in dwarf green market thinking will push the environmentally patched business as usual model towards collapse, which raises the question: Does the Thomas Kuhn's paradigm evolution loop predicts the future collapse of dwarf green markets?
I think yes, what do you think?
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Dear Lucio,
In my opinion, Thomas Kuhn's paradigm evolution loop can indeed be a valuable tool in understanding the future development (or decline) of so-called “dwarf green markets.” Kuhn argued that science (and, more broadly, cognitive paradigms in society) develops through revolutionary change rather than gradual evolution. In short, when the current paradigm ceases to explain reality and its internal contradictions become too severe, a crisis arises, leading to the emergence of a new paradigm.
In the context of sustainable development, the issue has long struggled with theoretical and practical inadequacies, as was clearly evident since the 1987 Brundtland Report. Despite efforts to implement sustainable development solutions, issues such as pollution and climate change continue to worsen. In this sense, as you yourself note, there is a growing inconsistency between sustainability theory and actual results. In Kuhn's model, we could interpret this as a sign of a growing crisis in the paradigm of the traditional market economy, which is unable to respond effectively to environmental challenges.
Besides, “dwarfing green markets” could be seen as an attempt to patch up the existing system, which is itself structurally flawed. The traditional market model, based on Adam Smith's principles that reward short-term profits and ignore long-term environmental costs, distorts the real prices of green goods. Green markets, which are largely part of the current system, do not offer a full paradigm shift - rather, they represent a minimal modification of the paradigm, attempting to introduce green principles into a model that was not designed with sustainability in mind.
Viewed from Kuhn's perspective, these “patched” systems have limited sustainability. If the price distortions and imperfections of the traditional market model continue to worsen, as seems inevitable in the face of growing ecological problems, the current paradigm could enter a crisis phase. This leads to the possibility of the collapse of “dwarf green markets” as too weak to survive, and the need to replace them with a new, more radical approach to sustainability.
In view of the above, it can be concluded that Kuhn's paradigm evolution loop actually suggests that the future collapse of dwarf green markets is highly probable. In the longer term, there may be a breakthrough that will replace the current imperfect solutions with a new paradigm based on more fundamental economic and social changes that will be better able to respond to the challenges of sustainable development.
I would hereby like to add that Thomas Kuhn's paradigm evolution loop can be interpreted as a key model to explain both the potential demise of “dwarf green markets” and the need to implement a fundamental green transformation of the economy. Sustainable economic development, the green transformation of the economy, and the development of fully green markets are concepts that go beyond Adam Smith's traditional market paradigm, based on short-term profits and ignoring long-term environmental costs. The rationale for pursuing a green transition is based on the fact that only by building a zero-carbon, circular and environmentally responsible economy will it be possible to meet the challenges of sustainable development and minimize further negative impacts of climate change and ecosystem degradation.
To summarize these considerations of mine, Kuhn's paradigm evolution loop can be seen as an argument that without implementing fundamental changes in economic thinking, current “patched” models of sustainability, such as “dwarf green markets,” will not survive. Their place will be taken by more holistic and responsible economic models that are better suited to the challenges of the modern world. A circular economy, zero-carbon, based on renewable energy and integrated with corporate social responsibility, is the future that will truly achieve the Sustainable Development Goals.
I pointed out various aspects of this important issue for the future of the planet, the future of the planet's climate and biosphere, and for the future of future generations of people in my article:
IMPLEMENTATION OF THE PRINCIPLES OF SUSTAINABLE ECONOMY DEVELOPMENT AS A KEY ELEMENT OF THE PRO-ECOLOGICAL TRANSFORMATION OF THE ECONOMY TOWARDS GREEN ECONOMY AND CIRCULAR ECONOMY
I invite you to join me in scientific cooperation,
Kind regards,
Dariusz Prokopowicz
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When does a language become dead?
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when people stop using it their communication for one reason or another. Different factors can lead to language death; historical, political, cultural, economical, social, psychological, when? when the most of the previous factors meet together
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The process of collecting core samples in cases of structural failure is essential for understanding the root causes and evaluating the integrity of the structure. While specific guidelines may differ by location and circumstances, there are generally accepted procedures outlined in engineering and construction standards. Organizations like ASTM International and national building codes provide recommendations for core sampling location, safety protocols, and sample analysis?
Adhering to such standards is critical to ensure the accuracy of the collected data. This data, in turn, assists in investigating structural failures and devising appropriate remediation strategies. Engineers and professionals undertaking core sampling during structural failure investigations should consult relevant standards to ensure that best practices are followed.
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When collecting core samples in cases of structural failure, it's crucial to follow specific guidelines to ensure accurate analysis and diagnosis of the failure. Here are some general guidelines:
1. Safety First:
Prioritize safety for yourself and others involved. Assess the stability of the structure before taking any samples. Wear appropriate personal protective equipment (PPE) and follow safety protocols.
2. Document the Site:
Take detailed photographs and notes of the site before taking any samples. Document the overall condition of the structure, the location of the failure, and any visible signs of distress.
3. Identify Failure Mode:
Understand the type of structural failure (e.g., shear failure, flexural failure, buckling). This information will guide the sampling strategy.
4. Strategic Sampling:
Plan your sampling locations strategically based on the suspected failure mechanism. For example, if there's a crack, sample from the crack location and extend the sampling to areas that show different degrees of distress.
5. Use Appropriate Tools:
Select the right tools for core sampling based on the material of the structure. For concrete, use a diamond-tipped core drill. For other materials, use tools suitable for the job.
6. Sample Size and Orientation:
Take core samples of sufficient size to capture the failure mechanism. Ensure that the orientation of the core samples is consistent and aligns with the suspected failure mode.
7. Depth of Sampling:
Sample deep enough to capture the full extent of the failure. If possible, sample beyond the visibly damaged area to analyze unaffected material.
8. Preservation of Samples:
Preserve the integrity of the samples. Handle them carefully, and store them in appropriate containers to prevent contamination or damage during transportation.
9. Labeling and Documentation:
Clearly label each core sample with information such as the location, depth, orientation, and any relevant observations. Document the sampling process thoroughly.
10. Transportation:
Transport the core samples to the laboratory promptly and under controlled conditions to prevent alterations in the material properties.
11. Laboratory Analysis:
Work with qualified professionals and laboratories for detailed analysis of the core samples, including material properties, composition, and any signs of deterioration.
12. Important to know:
Always consult with structural engineers, geotechnical experts, or other relevant professionals to ensure that the sampling process is appropriate for the specific circumstances of the structural failure.
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Please put your possible thoughts and suggestions on the attached pictures and also if there are any possibilities of mitigating them...
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The structural collapse of columns in bridges can be attributed to various factors, including overloading due to accidents or extreme weather, corrosion from harsh environmental conditions, poor design or construction practices, lack of maintenance, foundation issues, vehicle collisions, vibration and fatigue, and the spacing of stirrups in the column. Stirrups are an essential part of the column's reinforcement, and inadequate spacing or improper installation can weaken the column's ability to resist lateral forces, making it more susceptible to collapse. Regular inspections, proper maintenance, adherence to safety standards, and attention to stirrups spacing during construction and reinforcement are crucial in preventing such failures.
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On 6 February 2023, an earthquake of Magnitude 7.8 struck southern and central Turkey and western Syria. Two major aftershocks of 6.7 and 7.5 Magnitude soon followed. Thousands of people have lost their lives and the death toll seems to be increasing rapidly. Although the earthquake occurred in a highly seismically vulnerable region, the footages from the disaster-stricken area show a high number of building collapses.
What could be the reason for such building collapses (based on preliminary information)?
Can it be attributed to flaws in building design? or problems in design implementation? or lack of routine maintenance? or a higher degree of ground acceleration than anticipated? or any other reasons?
Some possible general explanations can be found at:
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Can anyone provide the source of relevant ground motions?
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In the dynamic test of beam-column substructure, what is the basis for selecting the mass and impact velocity of drop hammer?
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I want to know about what is the reson behind , intial phase of stage constrcution in plaxis 2d result structure collapsed . any one help me .
please find the attechment below for intial phase result .
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It seem to me that you have a useless constraint that do not allows vertical movements. You should remove it. Please see the image attached.
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I'm willing to prepare a loess ( collapsible) soil in order to test it's collapse potential in accordance to the ASTM Standards.
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I agree with the proposed answers !
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According to modern regulations, the seismic design of buildings is based on the ability requirements of the correct design of the nodes and plasticity.
The (inevitable) inelastic behavior under strong seismic excitation is directed at selected elements and failure mechanisms.
In particular, the incorrect design of the nodes and the clearly limited plasticity of the components lead to major failures.
1) The philosophy of the correct design of the nodes of the regulations is characterized by the appropriate dimensioning of columns-beams so that we have plastic joints in the beams and not in the columns so that we do not have immediate collapse.
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Without the inelastic behavior the bearing would not show plastic joints in the beams.
I believe that displacement control is better than what they apply today which is nothing more than the management of inevitable inelastic displacement and failure.
Displacement control means no failure no plastic joint
It basically means controlling the deformation.
Deformation control also means control in failures since deformation and failures are directly connected.
If you do not have the ability to control the distortion then you manage it with the proper design of the nodes and that is good.
But being able to control the deformation of the construction is better.
2) The plasticity of structural elements and structures made of reinforced concrete is characterized by their ability to deform beyond the leakage limit, without significantly reducing their strength
According to § 5.2.1 of EC8 there is a design option of the available plasticity of the building.
Reinforced concrete buildings can be studied with two different design methods.
a) To be designed with the necessary ductility which means to have the required - necessary ability to consume seismic energy, but without losing their resistance to all loads during the rocking of the earthquake.
b) To be designed with low ductility, with low energy consumption, but with very high dynamics. The ductility or interoperability of the structural elements and nodes (exists) is achieved with the existence of the appropriate reinforcement, the construction devices, the proper dimensioning and the limitation of the axial loads to some limits.
Plasticity is a critical factor for seismic constructions for many reasons.
At the carrier level with inelastic analyzes you also find the levels of plasticity that the construction can develop.
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If the seismic energy (measured by ground acceleration) is too large, it will produce excessively large displacements that will cause a very high curvature in the vertical and horizontal elements.
If the curvature is too high, this means that the rotation of the sections of columns and beams will be well above the elastic area (Compressive concrete deformation over 0.35% and reinforcement fiber stresses over 0.2 %) beyond the leakage limit.
When the rotation exceeds this limit of elasticity, the structure begins to "dissolve the energy storage" through plastic displacement, which means that the parts will have a residual displacement that will not be able to be recovered (while in the elastic region all displacements are recovered).
Basically the design of the strength of a current building is limited to the limits of the elastic design range, and then passes to the default plastic leak areas, which are default areas of small and many leak failures, (usually designed to occur at the ends of the beams) so as not to collapse the structure.
This is the mechanism of plasticity that consumes seismic energy.
(Structure collapses when oblique / failed columns fail)
If the parts that experience the plastic deformations exceed the breaking point limit, and there are too many on the structure, the structure will collapse.
Basically, plasticity is achieved by placing a dense reinforcing connector at the ends of the elements because this helps to create many and small cracks, avoiding the creation of large catastrophic cracks.
Plasticity is directly related to the cooperation of concrete and steel (mechanism of relevance)
The most serious problem of relevance is created by the ultra-tensile strength of the steel, which turns the failure into a shear form, which is extremely brittle. When the shear stresses in the steel concrete interface reach their limit value, the correlation is destroyed in the form of concrete rupture.
Part of the reduction in stresses is achieved by increasing the overlap and reducing the diameter of the reinforcement bars. The increase of their limit value is achieved by increasing the strength of the concrete. The presence of transverse reinforcement acts favorably by restricting the opening of the developing cracks.
3) The columns or walls are rigid and flexible. It depends on the cross section in relation to the height and the beams that are connected etc. (Frames etc)
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Yes it is right ... the relationship between the height and the size of the cross section determines whether the elements are rigid or flexible.
But there are other factors such as the cross-sectional shape factor. A square column cross-section is more flexible than a cross-section of the same size which has the shape of a cross, angle or wall.
So we can design rigidly with walls if we want.
The walls may be located around the perimeter of the building (excluding shop facades) surrounding the stairwell and the elevator (strong cores) and may be internal walls (eg partition walls) throughout the height of the building. The installation of many strong walls implies, of course, due to their great rigidity, a significant reduction of the fundamental eigenperiod of construction. This, in combination with the view q = 1, leads to a correspondingly large increase in the seismic loads of the structure. However, it should not be overlooked that precisely because of the many and strong walls the strength increases more or conversely the cross-sectional loads decrease despite the increase of seismic loads.
Due to the fact that the wall has a double lever (that of height and that of width) the axial forces (kN) are smaller than they are in the column.
4) The diaphragm function ensures approximately the same movements of nodes in a plane (in a horizontal direction) which has the effect, among other things, to facilitate the analysis in space taking into account three degrees of freedom instead of six if you do not have a diaphragm. We should not confuse them with the walls. The coexistence of walls and columns is the most suitable formation for seismic structures made of reinforced concrete and especially for structures with many floors.
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Yes, correct for the diaphragm function of the plates.
The walls also have a diaphragm function under certain conditions. If the width and height do not have big differences then yes, and the walls are of diaphragm function. If they are both prestressed and anchored to the ground, then they are super diaphragmatic.
If you combine the diaphragm function of the slab and the compacted and prestressed walls, you have achieved complete rigidity, with zero same period and zero deformation which means zero failures.
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Brief Description of the Invention The principal object of the hydraulic tie rod for construction projects of the present invention as well as of the method for constructing building structures utilizing the hydraulic tie rod of the present invention is to minimize the aforesaid problems associated with the safety of construction structures in the event of natural phenomena such as earthquakes, hurricanes and very high lateral winds. According to the present invention, this can be achieved by a continuous pre-stressing (pulling) of both the building structure towards the ground and of the ground towards the structure, making these two parts one body like a sandwich. Said pre-stressing is applied by means of the mechanism of the hydraulic tie rod for construction projects. Said mechanism comprises a steel cable crossing freely in the centre the structure’s vertical support elements and also the length of a drilling beneath them. Said steel cable’s lower end is tied to an anchor-type mechanism that is embedded into the walls of the drilling to prevent it from being uplifted. Said steel cable’s top end is tied to a hydraulic pulling mechanism, exerting a continuous uplifting force.
The pulling force applied to the steel cable by means of the hydraulic mechanism and the reaction to such pulling from the fixed anchor at the other end of it generate the desired compression in the construction project.
The Patent Idea
We have placed on a table two columns, one column screwed on the table, and the other simply put on the table. If one shifts on the table, the unbolted column will be overthrown. The bolted column withstands the lateral loading. We do exactly the same in every column of a building to withstand more lateral earthquake loading. That is done, by simply screwing it to the ground. This pretension between the roof of the structure and the soil has been globally disclosed for the first time.
The invention stops the bending of the bearing vertical concrete elements by imposing compressive stresses on the cross sections. as well as the tipping moment, through the anchoring mechanism which anchors strongly under the foundation ground. It also creates an improvement in the bearing capacity of the soil in both compression and traction. Prefabricated structures made of reinforced concrete are the ideal constructions in which the invention has high efficiency and utility for the following reasons.
1) Prefabricated reinforced concrete structures are rigid and the imposition of compressive stresses on the cross section makes them even more rigid and improves the shear of the base. 2) The mathematical formula to find the moment of inversion is (force X height and the product is divided by the width of the wall) If we have a prefabricated two-storey reinforced concrete structure 7 meters high and with a frame width of 4x4 meters, which accepts a lateral force of 80 tons, the tipping moment will be (7X80 / 4 =) 140 tons If we place 2 tendons on each side of the prefabricated house, then each one must create a moment of stability> 70 tons.
If the same construction was based on 4 columns of dimensions 0.40X0.40X 7.00 meters then the moment of stability of the tendons would be much greater. (7Χ80 =) 560 tons 560/2 = 280 tons. So there is a big difference in dynamics, between the choice of columns and walls, and the stress of the tendons to the tensile stresses, and the anchors to the ground adhesion and the cross sections to the compression. So the choice of prefabricated is better.
3) Prefabricated houses are also industrialized and cost half the money that another construction costs.
These three main reasons are where they make the patent on prefabricated houses profitable. Both cheap and anti-seismic.
I'm not an expert in existing technology, but I'm very much an expert in the technology I suggest.
Please correct me if I am wrong in the following that I will say ....
Elasticity stores seismic energy and returns it to each seismic load cycle.
No failures are observed in this area of ​​elastic displacement However, seismic damping is created in the elastic displacement region by the friction of the materials which produce heat.
That is, they convert kinetic energy into thermal energy.
Prefabricated houses are completely rigid with almost zero period, and have zero seismic damping.
This is not good for prefabricated houses because seismic damping only does good.
When the ground acceleration is large the elastic construction creates large curves in the trunk of the beam and the pillar, and the elasticity begins to be lost and many small cracks are created at the ends of the beams.
These small cracks are the so-called plastic failure areas or so-called plasticity.
The mechanism of plasticity releases seismic energy, and this is good for construction.
This excess displacement outside the elastic region is the inelastic displacement region in which the plasticity mechanism occurs, but the structure does not return to its original position as it returns to the elastic displacement region.
If the earthquake is too big and the displacements will be too big and the curves in the trunk of the beam and the pillar will be too big and will create big cracks above the breaking point, and if there are many the construction will collapse.
Here's the weak point of the existing design.
In large earthquakes the existing design fails to control the inelastic displacement and the structures collapse.
If you increase the cross sections of the elements, the elasticity is lost, the seismic intensities increase as the mass increases, and the walls drop high torques at the base, due to the lack of elasticity.
Plasticity is also lost.
These stiffening factors create a large tipping moment in prefabricated houses, which creates a recoil in the total base area of ​​the house.
The building loses ground support.
As a result, a large torque, in the opposite direction of the overturning torque is created, which is responsible for the failures of prefabricated houses.
What the mechanism of the invention does is to create a moment of stability to balance the overturning moment, so that the construction does not lose ground support.
In high-rise prefabricated houses the problem grows.
With the patent we will build prefabricated skyscrapers, with lower cost and greater seismic response.
This stability force, the mechanism takes it from the ground, so it has no mass to increase the inertia intensities.
On the other hand, the mechanism deflects all the forces of the earthquake into the ground, preventing them from being directed to the cross sections of the beams.
Still The pre-tensioning in the cross-sections of the prefabricated houses increases their dynamics by eliminating the cutting of the base, and the shear failures.
Loose soils can be sandy or clay and there is definitely water in them.
In a medium-sized earthquake, these soils recede and the structures either tilt or collapse.
The mechanism of the invention is a tool which not only pre-compacts loose soils by exerting hydraulic pressures on the horizontal and vertical axis, (before construction) to increase their bearing capacity,
but strongly tightens the construction to the ground by assuming static loads and traction loads of the base.
Successfully dealing with both seismic waves (P) and catastrophic waves (S) without losing traction with the ground.
Experiment Findings EXPERIMENTAL ELEMENTS
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Interesting topic
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Dear researchers
As you know, one of the challenges of using nonlinear procedures is to determine the behavior of plastic hinges of members with deformation controlled action that this behavior is assigned to the plastic hinge by a force-deformation curve and its relations using parameters modeling. various researches has shown that the uncertainties in these modeling parameters significantly affect the structural responses.
Also, the acceptance criteria of different performance levels relating to the mentioned force-deformation curve are needed for performance-based design of structures.
There are two questions now:
1- Are force-deformation curves presented in ASCE 41-13 suitable only for nonlinear static analysis (push over)? or also is applicable for nonlinear dynamic analysis?
2- Given that the acceptance criteria presented in ASCE 41-13 are derived based on the mentioned force-deformation relations in this code (a, b and c modeling parameters), what acceptance criteria can be used to evaluate the structure at the IO, LS and CP performance levels if the other force-deformation relations presented in the technical literature (such as Lignos and Hartloper relations for beams and columns of moment frames, respectively) are utilized for concentrated plasticity modeling?
The mentioned curves (Lignos and Hartloper relations) are mostly used in structural modeling to study the structural collapse, in which the collapse is determined by the criteria mentioned in FEMA p-695 and as a result, acceptance criteria in accordance with these behavior curves have not been researched.
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1. Seismic codes suggest simplified force-deformation models in order to estimate the inelastic behavior both in monotonic and cyclic loading. The monotonic F-δ curve is considered as the envelope and the skeleton curve of F-δ loops under cyclic loading. The real inelastic behavior under cyclic loading depends on the material and the dynamic loading, e.g. reinforced concrete under seismic loading. So, stiffness and strength deterioration should be considered under cyclic loading in the concentrated plasticity modeling technique.
2. Uncertainties about deformation capacity are high beyond the point C of the F-δ curve. Even in the Collapse Prevention performance level (before point C), the ultimate deformations shows significant dispersion in experimental cyclic tests (e.g. reinforced concrete). Consequently, appropriate acceptance criteria for different performance levels and for different materials can be found in seismic codes (ASCE 41-13, FEMA, Eurocode, EN 1998-3, etc) or in other technical literature using model safety factors to scale down the proposed mean values to mean plus standard deviation ones.
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Hi dear community,
I am currently working on a project where I want to generate a 3D reconstructed model consisting of rubble piles (in consequence of a building collapse) via remote sensing. In my case, I employ LiDAR aerial laser scanner as well as aerial photogrammetry for point cloud generation of the disaster scene. The problem is that solely the surface of the scene that lies in the field of view can be reconstructed. However, in order to evaluate the structural behavior of the debris with regards to structural stability, I need to know how the collapsed elements are structured beneath the debris surface. Does somebody has an idea how I can proceed or has anybody conducted a related study? Is my objective even feasible?
Thank you in advance!
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Dear Amir,
I have worked with ground-based Lidar and with terrestrial GPR (Ground Penetrating Radar). Lidar can not penetrate a solid rubble pile and GPR does not work well on rubble, especially if the surface is irregular...
Respectfully yours, Joel
J
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Geotechnical Engineering is a branch of Civil Engineering that deals with the behavior of earthen materials and how they interact with man-made elements such as foundations, and infrastructure.
The practice of forensic geotechnical engineering is the application of geotechnical engineering to answer questions pertaining to a conflict in the legal system.
Geotechnical engineers must apply science and engineering within the rules
and practice of the legal system In order for their work to be effective in representing reality.
Forensic Geotechnical Engineering involves analysis of a project, site conditions, or construction from a geotechnical standpoint. Analyses of failures connected with geotechnical and geological origin to improve professional practice, codes of analysis and design as well as practice. These analyses are performed to check the calculations and engineering assumptions during and/or after the construction of a project to provide quality assurance or address issues that arise during or after construction.
Common issues that may arise that a forensic geotechnical analysis can help with include:
  • Expansive Soils Related problems
  • Collapsible Soils related problems
  • Settlement of Shallow and Deep Compacted Fill Soils
  • Pavement excessive Settlement and Failures
  • Slope Stability Failures
  • Embankment Failure
  • Foundation Failures
  • Excavation Failures
  • Others
For more readings on forensic geotechnical engineering:
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Having done a good deal of this kind of work, it is important to understand that this is more than just technical exercise. It is important to understand the standard of care and local practices by which the performance is judged. The American Consulting Engineers Council has an excellent publication on this topic: https://docs.acec.org/pub/18803059-a2fd-2d06-cc39-a6d1dd575265.
It is also important to understand the roles of all parties to the case. Failures are seldom the result of a single error or oversight, but often are the result of a perfect storm of factors involving multiple parties from the initial investigation, design assumptions, owner inputs, contracting limitations, information sharing, construction practices, etc.
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I am looking for a numerical model, equation or law, which supports the ground subsidence due leakage in underground water pipelines or interaction of water and subsurface soil.
Thank you
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See chapter 9 in the book "Hydrology of Disasters" By Vijay Singh.
Also see this book chapter:
Formulations gave in both.
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Hi, im working on a project of this collapsible bridge. Im confused as to which element i should consider and what boundary conditions to assign them to. (rollers, fixed,free.. etc)
Can anyone assist?
The bridge have a UDL of 40,000N on it. being at 396509.3N heavy. It is also 12.12m long.
Model of my bridge and a sample of what handwritten infomation i require is as attached. Changes to alter its design is possible.
Appreciate the help!
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HELLO
ROTATE AT ONE DIRECTION AND NO TRANSLATION IN 3 DIRECTION "DEPEND ON THE DEFINE OF X,Y,Z AXIS"
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We are witnessing spurt in collapse of bridges in recent years which is a cause of concern for bridge designers!
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Following the answers
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I'm working on alginate-based hydrogels and I want to observe the microstructures (porosity, roughness, etc.). The hydrogels were produced by gelation in aqueous calcium chloride. SEM is out of the question since that would require drying which would collapse the structures.
I'm considering TEM, is this advisable? Although, I would appreciate if anyone can suggest something less expensive.
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Google your question. You'll see there are multiple protocols for SEM specimen preparation of your material. I would not advise to use TEM.
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What is effect on the settlement rate of soil?
  1. First when water leaks from sewer or water pipe leaks continuously (non-cyclic flow) from an underground pipeline?
  2. Secondly when the water from sewer or water pipe leaks non-continuously (Cyclic flow) from an underground pipeline?
  3. If possible i need a Reference for the answer too.
Thank you in advance
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Mr.Haibat,
The collapse mechanism of soil when interact with water is purely depends on type of soil and its characteristics. For example: clay is an impermeable material so during continuous leakage of water then soil is going to be soften and lose it strength. In general, soil behaviour is depends on particle to particle contact stress that influence on engineering properties of soil. So, imagine the moment water is going to interact with soil slowly the bonding b/w soil broken then its starts failing. If there is cyclic change in water table level then downward vertical movement increase in one type of soil but in another case the movement is going to be upward. In expansive clay soil when moisture increases its volume starts increased and if moisture decreased its volume starts decrease. If you have fine silty sand in contact with soil the capillary pressure develop at the contact and increase its strength due to this phenomenon. i recommend you to tread any soil mechanics text book for ready reference on these aspects. You read the soil mechanics book authored by Karl Terzaghi.
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hi all,
i use Cu particles in size of 1 micrometer to make a film.
i sinter the film at 600 in air and then reduce the oxidised Cu to metal state at 300 in pure h2 or H2/Ar atmosphere.
i noticed that the particles collapse after this process and the film becomes very unstable. i don't understand why spherical Cu particles lose their shape and become much smaller after this. film is mostly unstable after reduction.
any comment or method to avoid this is appreciated.
thanks
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Yes
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The Ultimate Anti-Seismic System My name is Ioannis Lymperis and I live on a small island of Greece called Ios I have a patent for the anti-earthquake technology of construction I have invented a design method and a mechanism that joins the nodes of the highest level of the structures with the foundation soil in order to stop the deformations.
The control of structural deformations in a major earthquake is associated with the brittle damage of the structure.
The question is. Do you want to work together? Do you want research collaboration to prove the theoretical and experimental results of the project? I would be delighted to have a positive answer. I have a solution to all the problems of the earthquake. My applied theoretical and experimental research has a ten-year duration.
The simplest description of the method I can do is that if we join the nodes of the highest level with foundation ground, it will withstand larger lateral overturning forces than another wall that simply rests on on the ground. If we stop the primary torque of the wall overturning by this method we have stopped the displacement of the structure. By controlling the displacement of the structure, you also control the failures .
It is a method that uses a mechanism to pontoon all the upper edges of the construction walls with earth and which dynamically deflect the lateral load of the earthquake through the vertical support of the walls and the tendon of the mechanism, and directs them into the ground controlling in this way the displacements of the construction which causes deformations responsible for structural failures on the trunks of bearing elements.
Brief Description of the Invention
The principal object of the hydraulic tie rod for construction projects of the present invention as well as of the method for constructing building structures utilizing the hydraulic tie rod of the present invention is to minimize the aforesaid problems associated with the safety of construction structures in the event of natural phenomena such as earthquakes, hurricanes and very high lateral winds. According to the present invention, this can be achieved by a continuous pre-stressing (pulling) of both the building structure towards the ground and of the ground towards the structure, making these two parts one body like a sandwich. Said pre-stressing is applied by means of the mechanism of the hydraulic tie rod for construction projects. Said mechanism comprises a steel cable crossing freely in the centre the structure’s vertical support elements and also the length of a drilling beneath them. Said steel cable’s lower end is tied to an anchor-type mechanism that is embedded into the walls of the drilling to prevent it from being uplifted. Said steel cable’s top end is tied to a hydraulic pulling mechanism, exerting a continuous uplifting force. The pulling force applied to the steel cable by means of the hydraulic mechanism and the reaction to such pulling from the fixed anchor at the other end of it generate the desired compression in the construction project.
My own experiment. The model in this experiment https://www.youtube.com/watch?v=RoM5pEy7n9Q From 2.45 minutes to 2.50 minutes, that is, within 5 seconds, made 20 journeys of 25 cm ... so in 20 seconds made 80 journeys with 25 cm of oscillation width. These oscillations from one end to the other measure, and their respective time in sec. Frequency (Hz) is the fraction: v = number of such paths / corresponding time. 80/20 = 4Hz ...9.81 is the acceleration of the earth and we divide it with the acceleration we found to find the g. That is, how many times the acceleration is accelerated by a body that falls on the earth. In a natural earthquake I did this experiment with a 0.25 cm oscillating amplitude and a frequency of 4 Hz we have an acceleration ... a = (- (2 * π * 4) ^ 2 * 0.22) / 9.81 3,14x2 = 6,28x4 = 25,12X25,12 = 631,0144X0,22 = 157,754 / 9,81 = 16 g acceleration The specimen in the experiment had a general mass weighing 880 kg. The second floor because of the inverted beam it carries is more pounds than half so I would say it is about 450kg and the ground floor is 430kg So to find the inertia force F first on the ground floor we say ... F = m.a 430 Χ 157,754 = 67834,22 Newton or 68 kN. and the first floor 450 Χ 157,754 = 70989 Newton or 71 kN. Total force F (Inertia) 68 + 71 = 139 kN Moment of inertia Strength X Height ^ 2 Ground floor 68Χ0,67Χ0,67= 30,53 kN First floor 71Χ1,35Χ1,35 = 129,4 kN Total Inertia Torque 30,53+129,4 = 160 kN
Τhe patent achieves the following
1)The consolidation of the nodes of highest level of the walls with the ground, using the mechanism of the invention, deflects the upward tensions created by the wall overturning torque transporting them freely and directly from the roof into the ground and in this way stops the displacements responsible for all growing tensions on the body of the bearing elements which they cause inelastic bending deformations and failures in a major earthquake. 2 ) Also the mechanism and method of anchoring provides very strong foundation in soft soils 3)The wall receives only compressive stresses at both ends a) at the upper end b) and the facing lower end near the base. Does not exist anymore tensile strength. This means that there are no longer torques in the nodes Does not exist anymore mechanism of concentric forces failure The floor mechanism (soft floor) does not exist anymore 4) Does not exist anymore coordination because the whole construction is shifted with the same frequency and the same oscillation amplitude 5) The wall also receives horizontal shear forces. Apply tension at all edges of the wall with the patent mechanism increases the ability to horizontal shear forces.
Publication of the applied research of the project in a scientific journal with peer review
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Thank you very much for your interest!!! I want you to tell me how you can help me. With Mathematical calculations, experiments, writing together a scientific paper; ...how?
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The recent collapse of the Brumadinho dam in the Brazilian state of Minas Gerais, raises the question of continuous dams and dikes failures around the globe.
Why do these dams collapse? What can be done to limit these failures?
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Thank you all for your great contributions Henry Balderama, Mohammad Hooshmandzadeh and Om Prakash Chhangani.
Darren Lumbroso, that's an interesting project and thanks for the inspiring links. We are trying to create a global database of socioeconomic and ecological impacts of dam failures.It will take time,but we will get there.
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I am using Opensees to model the steel perimeter frame considering nonlinear hinges with panel zones for IDA analysis of three-story steel moment resisting frame. I have two issues: selecting nonlinear parameters for elements and effect of gravity load in IDA analysis.
For selecting nonlinear parameters, I need advice for assigning reasonable nonlinear parameters for hinges and properties for panel zones so that the IDA could capture all structural response before collapse.
For assigning gravity load, I modeled the frame considering leaning column with 50% gravity load on the leaning column and the remaining load as uniformly distributed loads in the main frame. However, the structure collapse at very low level of seismic events. For example, when I scaled the ground motion with 0.10 g, the structure collapsed . On the other hand, when I apply only 15% of the total gravity load on the leaning column and no gravity loads on the main frames, I got some results for ground motions scaled from 0.5 to 4.0 g.
Please advise me on how I can improve the model for IDA analysis and get satisfactory results.
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Interesting..
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Dear colleagues,
I have a case at a field at a Norwegian farm which has excessive calcium levels. How can this be reduced in the best way? I´m looking for a procedure.
Some data on the field:
- Total exchange capacity (TEC) is 7,32 (silty sand)
- Active pH is 7,9
- Calcium saturation is 95,4 % - desired 66 %
- Magnesium saturation is 1,4 % - desired 14 %
- Potassium saturation is 1,1 % - desired 5,3 %
- Sodium saturation is 0,4 % - desired 0,9 %
- Among the micronutrients boron and manganese are low.
- The soil structure is collapsed (over-flocculated)
The reason for this extreme calcium saturation is that the field had calcium stabilized sewage sludge applied some 17 years ago. Since then almost nothing has grown there. The farmer, and we, are looking for solutions. It is an organic farm.
My own first suggestion is the apply elemental sulphur (S) in high doses (to acidify and leach out Ca as CaSO4) and , i.e. 100 kg/ha plus kieserite and potassium sulphate (200 kg/ha of each).
Looking forward for your input! Thank you in advance!
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Dear Melese Temesgen,
Thank you for your input! Do you have a ny suggestions for suitable root crops with high oxalate levels? Thankful for your answer!
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In my research, I intend to compare drug loading with respect to the metal center. For this I need a Zn MOF with either BDC (Terephthalic acid) or BTC (Trimesic acid).  
Mostly studied Zn BDC MOF is MOF-5. But as it is unstable in aqueous solutions I cant use it for my application of drug loading.
Analog found for Zn BTC MOF is Zn HKUST-1, which is not porous as the structure collapse upon solvent exchange.
Are there any other suggestions for a porous stable MOF with Zn as the metal center and either BDC or BTC as the organic ligand ? 
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Use the CPO-27/MOF-74 series, water and air stable for the most part and the same framework can be made with a variety of different metal centres
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for progressive collapse design methods we have direct and indirect methods, tie force method can be implemented by pre-stressing cables as an indirect method or not and why.
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It can be used by carefully selecting their position, and predicting their strength and deformation under possible load cases and combination.
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In my study, i want to perform masonry building collapse as well as fracture response when subjected to large magnitude of ground-borne vibration. similar to the video link attached .
Can someone guide me on the analysis procedure for this case of study?
What is the specific material properties need to be applied apart from density,elasticity and plasticity?
Best regards. 
**my macro-modelling concrete masonry model
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The inertial model which aims at estimating seismic forces, the basis of structural design, has been questioned in the past few years since the way it represents the behavior of structures during an earthquake seems to be very limited, particularly when the structure collapses on soft soil, where damages increase significantly. The inertial model has its origin in the rigid body mechanics and is intended to estimate seismic forces in the current design methods which are earthquake resistant; this is why it has been questioned in recent years, to represent the behavior of structures during an earthquake in a very limited way, particularly on soft soil. The inertial model cannot be applied to structure behavior in soft soil. Instead, ground displacement should be considered during an earthquake. The failure mechanism in soft soil is associated with the gravitational forces that generate shear strengths in the vertical plane of any structure, associated with the vertical and slow undulating motion of the ground (for a large predominantly long period).
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Structural design should consider movements generated during the earthquake but even if forces generated in the structural elements are long-term