Concrete - Science topic

Kindly greetings,

In a conference I attended before, the peer reviewers believed that the flexural strength, compressive strength, and Young's modulus in the submitted manuscript could not fully represent the mechanical performance of concrete. I would like to ask professors and colleagues, what is the detailed mechanical characteristics of concrete should be included?

Thank you to everyone who saw it!

In the Netherlands, there is much concern about the distance between citizens and government and the lack of mutual trust in each other. Some say this is a result of technology - algorithms and automation of many activities are making the relationship between government and citizen (national but also local) increasingly businesslike and formal. AI could further increase this distance. There are also those who believe that AI can actually help make government more human and improve government-citizen contact. What do you guys think about this and are there people here who know of concrete examples or studies where AI is helping to make government more trusting and human?

Concrete subjects translate easier.

I am trying to simulate a rectangular short column (L/D ratio of 2) for cyclic load under axial compression. I am using the concrete damage plasticity model for concrete. The first problem I am facing is excess lateral stiffness in my ABAQUS model as you can see in the force vs displacement curve. I am trying to match the slope of the red curve generated by the cyclic hysteresis response of the column. The dashed line is the result I got. I have only included the elastic property for concrete for this instance. All the pictures related to the analysis are listed below.

Can anyone tell me what I am doing wrong?

I need to test fire performance of concrete cubes (150 mm * 150 mm * 150 mm). May I know about what kind of arrangement need to conduct this test at home? It shouldn't be a scientific one. But it should have been used to measure fire performance of concrete.

"How do we understand special relativity?"

Discussion

"How do we understand special relativity?"

The Quantum FFF Model differences: What are the main differences of Q-FFFTheory with the standard model? 1, A Fermion repelling- and producing electric dark matter black hole. 2, An electric dark matter black hole splitting Big Bang with a 12x distant symmetric instant entangled raspberry multiverse result, each with copy Lyman Alpha forests. 3, Fermions are real propeller shaped rigid convertible strings with dual spin and also instant multiverse entanglement ( Charge Parity symmetric) . 4, The vacuum is a dense tetrahedral shaped lattice with dual oscillating massless Higgs particles ( dark energy). 5, All particles have consciousness by their instant entanglement relation between 12 copy universes, however, humans have about 500 m.sec retardation to veto an act. ( Benjamin Libet) It was Abdus Salam who proposed that quarks and leptons should have a sub-quantum level structure, and that they are compound hardrock particles with a specific non-zero sized form. Jean Paul Vigier postulated that quarks and leptons are "pushed around" by an energetic sea of vacuum particles. 6 David Bohm suggested in contrast with The "Copenhagen interpretation", that reality is not created by the eye of the human observer, and second: elementary particles should be "guided by a pilot wave". John Bell argued that the motion of mass related to the surrounding vacuum reference frame, should originate real "Lorentz-transformations", and also real relativistic measurable contraction. Richard Feynman postulated the idea of an all pervading energetic quantum vacuum. He rejected it, because it should originate resistance for every mass in motion, relative to the reference frame of the quantum vacuum. However, I postulate the strange and counter intuitive possibility, that this resistance for mass in motion, can be compensated, if we combine the ideas of Vigier, Bell, Bohm and Salam, and a new dual universal Bohmian "pilot wave", which is interpreted as the EPR correlation (or Big Bang entanglement) between individual elementary anti-mirror particles, living in dual universes.

Reply to this discussion

Fred-Rick Schermer added a reply

Abbas Kashani

A lot to work with, Abbas.

However, I am standing in a completely different position, and want to share my work with you. I hope you are interested about this completely distinct perspective.

My claim is that Einstein established a jump that is not allowed, yet everyone followed along.

Einstein and Newton's starting point is the behavior of matter through space. As such, one should find as answer something about the behavior of matter moving through space, and yet Einstein did not do that.

To make the point understandable quickly, Einstein had not yet heard about the Big Bang yet. So, while he devised his special relativity, he actually had not incorporated the most important behavior of matter through space.

Instead, he ended up hanging all behaviors of matter on spacetime. It does not matter that his calculations are correct.

--

Let me find a simple example to show what is going on.

We are doing research on mice in a cage, and after two years we formulated a correct framework that fully captures all possible behaviors of these mice in the cage. That's the setup.

Now comes the mistake:

The conclusion is that the cage controls the mice in their behaviors.

Correctly, we would have said that the mice are in control of themselves, yet the cage restricts them in their behavior. We would not say that the cage controls the mice.

Totally incorrect of course, and yet that is what Einstein did. He established a reality in which matter no longer explains the behavior of matter through space, but made it space (spacetime) that explains the behavior of matter. It is a black&white position that has to be replaced by the correct framework (which is a surprise because it is not based on one aspect, but on both aspects).

--

I know I am writing you from a perspective not often mentioned, and it may not interest you. I'll find out if you are interested in delving deeper into this or not.

Here is an article in which I delve into this matter more deeply:

Article On a Fully Mechanical Explanation of All Behaviors of Matter...

Wolfgang Konle added a reply

"Richard Feynman postulated the idea of an all pervading energetic quantum vacuum. He rejected it, because it should originate resistance for every mass in motion, relative to the reference frame of the quantum vacuum."

Richard Feynman's idea is perfect, and there is no reason to reject it. The existence of vacuum energy, or better dark energy is consistent with Einstein's field equations with a positive cosmological constant.

The energy gain from mass or energy in motion leads to an increasing dark energy density.

The only idea which is missing, is the answer to the question: What happens with the additionally gained energy density?

As an answer to that question I propose the following working hypothese:

This energy is used to recycle star fuel from black holes.

On a first glance, this answer looks as being pure madness, because black holes with their unconvincible gravity seem to be a deposit of matter for eternity.

But in fact there is a plausible possibility. This has to do with the negative energy density of gravitational fields and the non-existence of a negatively definite energy density.

But we need open minded thinking in order to delve deeper into details.

Sergey Shevchenko added a reply

"How do we understand special relativity?"

- the answer to this question, which is really fundamental one, since is about what is some physical theory as a whole; what really means – why and how the postulates of a theory, in this case of the SR, really are formulated, and why and how the postulates

- which in any theory fundamentally – as that happens in mathematics, where axioms fundamentally cannot be proven – aren’t proven; while are formulated only basing on some experimental data, which fundamentally prove nothing, though one experiment that is outside a theory prediction proves that this theory is either wrong, or at least its application is limited.

Returning to the SR, which is based on really first of all four postulates – the SR-1905/1908 versions relativity principle, SR-1905 also on the postulate that light propagates in 3D XYZ space with constant speed of light independently on light source/ an observer’s speeds; and, additionally,

- in both theories it is postulated (i) that fundamentally there exist no absolute Matter’s spacetime, and (ii) - [so] that all/every inertial reference frames are absolutely completely equivalent and legitimate.

In the standard now in mainstream physics SR-1908 additionally to the SR-1905 it is postulated also that observed contraction of moving bodies’ lengths, and slowing down of moving clocks tick rates, comparing with the length and tick rates when bodies and clocks are at rest in “stationary” frames, is caused by the “fundamental relativistic properties and effects”, i.e. “space contraction”, “time dilation”, etc..

Really from yet the (i) and (ii) postulates any number of really senseless consequences completely directly, rigorously, and unambiguously follow, the simplest one is the Dingle objection to the SR;

- from this, by completely rigorous proof by contradiction completely directly, rigorously, and unambiguously it follows , first of all, that

- Matter’s spacetime is absolute, that so some “absolute” frames that are at rest in the absolute 3DXYZ space can exist, while applications, i.e. measurements of distances and time intervals, of moving in the space inertial frames aren’t completely adequate to the objective reality; and

- there exist no the “relativistic properties and effects”.

Etc. However really the SR first of all is based on the indeed extremely mighty Galileo- Poincaré relativity principle.

That is another thing that

- according to SR-1905 relativity principle there is some extremely potent entity “light”, the constancy of which for/by some mystic reasons/ways forces moving bodies to contract and moving clocks to slow down tick rates; and

- the SR 1908 relativity principle is practically omnipotent, so the moving frames, bodies, clocks for/by some mystic reasons/ways really contract/dilate even evidently fundamental space and time.

All that above in the SR really is/are only postulated illusions of the authors, nonetheless, again, the Galileo- Poincaré relativity principle is really . extremely mighty, and the SR indeed in most cases at everyday physical practice is applied in completely accordance with the objective reality. The fundamental flaws of the SR reveal themselves only on fundamental level.

The post is rather long now, so here

Cheers

Sergey Shevchenko added a reply

So let’s continue about what is “special relativity”

In the SS post above it is pointed that Matter’s spacetime is fundamentally absolute, however to say more it is necessary to clarify - what are “space” and “time”, just because of the authors of the SR – and whole mainstream physics till now - fundamentally didn’t/don/t understand what these fundamental phenomena/notions are, the really mystic and simply fundamentally wrong things in the SR were/are introduced in this theory.

What are these phenomena/notions, and what are all other really fundamental phenomena/notions, first of all in this case “Space”, “Time”, “Energy”, “Information”,

- and “Matter”– and so everything in Matter, i.e. “particles”, “fundamental Nature forces” – and so “fields”, etc., which is/are fundamentally completely transcendent/uncertain/irrational in the mainstream philosophy and sciences, including physics,

- can be, and is, clarified only in framework of the Shevchenko-Tokarevsky’s philosophical 2007 “The Information as Absolute” conception, and more concretely in physics in the SS&VT Planck scale informational physical model, in this case it is enough to read

More see the link above, here now only note, that, as that is rigorously scientifically rationally shown in the model, Matter absolutely for sure is some informational system of informational patterns/systems – particles, fields, stars, etc., which, as that is shown in the model, is based on a simple binary reversible logics.

So everything that exists and happens in Matter is/are some disturbances in the Matter’s ultimate base – the (at least) [4+4+1]4D dense lattice of primary elementary logical structures – (at least) [4+4+1]4D binary reversible fundamental logical elements [FLE], which [lattice] is placed in the Matter’s fundamentally absolute, fundamentally flat, fundamentally continuous, and fundamentally “Cartesian”, (at least) [4+4+1]4D spacetime with metrics (at least) (cτ,X,Y,Z, g,w,e,s,ct); FLE “size” and “FLE binary flip time” are Planck length, lP, and Planck time, tP.

The disturbances are created in the lattice after some the lattice FLE is impacted, with transmission to it, by some non-zero at least 4D space, momentum P[boldmeans 4D vector] in utmost universal Matter’s space with metrics (cτ,X,Y,Z). The impact causes in the lattice sequential FLE-by-FLE flipping, which, since the flipping cannot propagate in the lattice with 4D speed more than the flipping speed c=lP/tP [really at particles creation and motion c√2, more see the link, but that isn’t essential here].

Some FLE flipping above along a direct 4D line can be caused by a practically infinitesimal P impact; but if P isn’t infinitesimal, that causes flipping FLE precession and corresponding propagation of the “FLE-flipping point” in the 4D space above along some 4D helix,

- i.e. causes creation of some close-loop algorithm that cyclically runs on FLE “hardware ” with the helix’s frequency ω, having momentum P=mc above, mis inertial mass, the helix radius is λ=λ/P;

- and the helix’s 4D “ axis” is always directed along P – particles are some “4D gyroscopes”.

The post is rather long already, so now

Sergey Shevchenko added a reply

So let’s continue about what is “special relativity”.

In the SS posts above it is pointed that everything that exists and happens in Matter is/are some disturbances in the Matter’s ultimate base – the (at least) [4+4+1]4D dense lattice of FLEs, which [lattice] is placed in the Matter’s fundamentally absolute, fundamentally flat, fundamentally continuous, and fundamentally “Cartesian”, spacetime,

- and that happens always in utmost universal “kinematical” Matter’s space with metrics (cτ,X,Y,Z), and corresponding spacetime with metrics (cτ,X,Y,Z ct), where ct is the real time dimension.

At that particles, most of which compose real bodies, at every time moment exist as “FLE –flipping point” that move along some4D helixes that have frequencies ω, having 4D momentums P=mc, m are inertial masses, a helix radius is λ=λ/P;

- and the helix’s 4D “ axis” is always directed along P – particles are some “4D gyroscopes”.

So in Matter there exist two main types of particles – “T-particles”, which are created by momentums that are directed along the cτ-axis [more generally – by 4D momentums cτ-components, but here that isn’t too essential], and so, if are at rest in the 3DXYZ space, move only along cτ-axis with the speed of light, and at that a T- particle’s algorithm ticks with maximal “own frequency”, the particle’s momentum is P0=m0c, where, correspondingly, m0 is the “rest mass”.

If a such T-particle, after some 3D space impact with a 3D space momentum p, moves also in 3D space with a velocity V, having 4D momentum P=P0+p, its speed along the cτ-axis decreases by the Pythagoras theorem in (1-V2/c2)1/2 , i.e. in reverse Lorentz factor,

- and, at that, despite that the helix’s frequency increases, the algorithm is “diluted by “blank” 3D space FLEs flips. So the “own frequency above” decreases in Lorentz factor, so the algorithm ticks slower; and so, say, moving clocks that are some algorithms as well, tick slower in Lorentz factor as well; if a particle algorithm has some defect, and so at every its tick it can break with some probability, so the particle is unstable and decay, such moving in 3D space particles live longer.

Nothing, of course, happens with time, there is no any the SR’s “time dilation”.

The post is rather long already, so now

Cheers

Hello Researchers & Professors,

Limited research has been done on effect of high strain rate on concrete due to blast loading using machine learning techniques. According to study we want to collect experimental data ie database of high strain rate to apply new machine learning techniques. Humble request if someone have data about strain rate , kindly share us . so that we can use new approach for better results.

thanks & Regards

What is the ratio of compressive strength to tensile strength of concrete and difference between the tensile strength, breaking strength, and compressive strength of concrete?

I am working on designing evolution algorithm based scheduling algorithm using ifogsim. Before that, I want to simulate existing algorithms using ifogsim. Can someone help me on this?

Note: In source code, there is a folder named scheduler.There is a TupleScheduler class in that. I can change this. But at the sametime i may need to change AppModule policy too. Actually I need a concrete suggestion about where to change in ifogsim source code?

Nanomaterials in a powdered form are challenging to use in laboratory concrete specimen casting. This is due to the minute-sized particles and the safety considerations. Therefore, there is a need to use nanomaterials in liquid form without altering their properties when used in the casting of concrete specimens.

After Concrete pouring for beam or other elements, Alkalinity level of concrete increases due to forming of Calcium hydroxide and heat comes out well. My question is, would that alkalinity level persist continuously ?

I want to train neural networks to evaluate the seismic performance of bridges, but the papers online are all based on their own databases and have not been published. Where can I find the relevant dataset? The dataset can include the following content: yield strength of steel bars, compressive strength of concrete, number of spans, span length, seismic intensity, support type, seismic damage level, etc

Actually, I have a CDP model sheet for normal concrete, but I want a sheet for UHPC and Lightweight concrete..!

All the experts kindly guide me ..Thank You so much for your precious time.

1. Fire 2. Earthquake 3. Flood

But the big bill comes from 4. not maintaining them. How can we maintain the structures if we can't?

Because the buildings will start falling down on their own.

Insulation. We cover everything. We cover everything with external insulation and plasterboard. External walls, ceilings, load-bearing structure made of reinforced concrete, all covered with insulation and plasterboard.

From the inside, plasterboard on ceilings and walls

What a nice coolness, but there goes the visual control.

1.And there's an earthquake. How do I see the crack to repair it? In the next earthquake either the crack will get bigger or the ceiling will come down on our heads. In corner columns you can't see any failure from the inside because the inside of the column is covered by the masonry.

2.And rusting an iron breaks the concrete overlay and the concrete and steel cooperation is lost How do I repair something I don't see; neither in the ceiling nor in the column?

3.Catch a fire We will burn like candles. Do you know how nice styrofoam burns?

Hi everyone and senior researchers,

I am currently on experimenting the shrinkage of SCM (Supplementary Cementitious Materials) Infused concrete.

I made 6 specimens with same specimen size in 1 mixing to make sure that the specimen have similar mechanical properties.

After mixing, i let them hardened in the mold for a day

And the next day, demoulded and started measuring the initial shrinkage of specimens

Then, after measuring, 3 of the specimens were put into room with higher temperature and another 3 into the room with standard condition 25 degree C.

Then keep measuring.

However, as the day increases, the shrinkage rate of the specimens in higher degree temperature room show higher than that of specimen in standard condition, until the shrinkage rate starts stablizing and both the shrinkage from two different rooms meet at some point around 60 days.

So while doing this calculation, i had also considered the effect of the coefficient of thermal expansion of concrete and subtracted that expansion due to the thermal expansion.

So What i am wondering is although I had same mix design in one batching with same properties just with different temperature, which i had make up for by adding the thermal expansion of concrete, why is the two shrinkage rate still difference . What parameters am i missing while considering ? Please kindly answer my questions if anyone thinks i am missing something

I am using electrical resistivity tomography (ERT) method to analysis cacks in concrete

Dear all, we found these empty cylindrical cocncretions in severals ponds and lakes from different mountain range in Uzbekistan.

Any ideas of what it could be ?

The pictures have been took under binoculare lens (the structure are from 0.1 mm to 0.5 mm).

May be a root concretion of Cyperaceae or other hydrophytes from the ponds ?

Thank you for your help,

Lucas

We found two strange structures in fresh watered lake from elevation higher than 1500 m a.s.l in Nuratau and Zarafshan ranges:

1: cristal in X or in "star-shape". Any ideas ?

2: fluter cylinder which seems to be carbonated (or at least evaporitic). Could be a concretion build around aquatic plants ?

Thank you very much for your help !

Hi Everyone;

Can any one tell how we calculate the bond stiffness between steel and concrete, not Bond stree but Bond stiffness. and I wan to understand this formulation about Bond Stifness if anyone have information about it.

You Find the equation below.

Greetings and respect

I have done a non-linear analysis on a concrete water tower. It is important for me to know in which step and in which node the maximum of the first principal stress occurs.

Is there a way for the software, for example, for a 60-second analysis with a time step of 0.02, to automatically show the time of occurrence of the maximum of the first main stress, its location and its maximum value.

The ductility of concrete is described as its ability to undergo inelastic deformation before failure. It can be linked to toughness (a measure of the energy absorption capacity of the material) and used to characterize the material’s ability to resist fracture. Several studies have proposed nondimensional relative toughness indices (T.I.c) for FRC; these indices, irrespective of concrete strength, depend on the extent of the stress-strain curves obtained.

I am facing a problem with the simulation of the precast concrete beam with prestressing. Typically, a precast beam would be fabricated in the factory with prestressing tendons (precambering) to cater for the deflection due to long-span. That means the prestressing force resulted in bending moment in the precast beam portion only. It's not like post-tensioned beam where the prestressing is applied after the entire beam section has been formed. Therefore, to properly model the trapped in stress and strain in precast concrete beam, I need to model them in different stages.

What I am currently doing is to use the Interface_Springback keyword to write out the dynain file for the following analysis. This helps me to map over the deformed shape with the topping concrete mesh.

However, the dynain file only captures the initial solid and beam element stress. No strain would be copied over. So the concrete's compressive strain would be underestimated?

So I am wondering whether this is correct for the following analysis?

If I only copy over the initial stress and the deformed geometry, it will start with zero strain for all the elements.

Another option is I can copy over the initial stress of the precast concrete elements (with the beam elements for PT) but kept the initial geometry and then let the precast concrete elements deform under the initial stress. But that would cause the topping concrete elements to deform together which is not true.

Concrete Flexure Test

Concrete batching plant and construction area bring so much pollution to ambient air, such as PM or TSP and some are toxic. Apparently, build barrier wall or plant some vegetations still the better option to prevent air pollution spread out from plant or construction area. 

Do you know what technology is compatible for construction or batching plant areas? Or do you have some idea on how this reactor works (link)? It was UTEC air purification technology.

In planning a 19-story building, I want to use varied concrete grades—lower for slabs and beams, higher for columns (e.g., M50 for columns, M25 for beams and slabs). How much can I differ between these grades while ensuring structural strength and avoiding issues like cold joint formations at beam-column joints? I've heard about a maximum difference of 5N/mm^2, but I'd like clarification with references and reasons for this choice.

what we are working on is studying the friction between two concrete blocks

the bottom one is fixed and the top one is moving back and forth

in the experiments the concrete is deteriorating and the friction is decreasing

how I can model that in software

I tried in Ansys but the material is not deteriorating

I also tried to model it using Movable Cellular automata but I don't know how I will apply rules between the cells

Any Suggestions??

Steel rebar members used in reinforced concrete pillars. They do not come directly in contact with Oxygen and water so why do they corrode.

I have a simulation of a transition piece/connector piece between a concrete shaft and a steel T-flange. The T-flange rests on a leveling plate and is connected to the concrete through bolts on both sides. The concrete has post-tensioning cables.

I wished to find a better way to mimic the real process of first tensioning the cable, then adding grout on top of the cable and then tensioning the bolts.

My idea was to apply a very small Young's modulus to the grout-part while tensioning the cable. Then I changed the Young's modulus of the grout to a suitable value in it's own step using field parameters before tensioning the bolts in the next step.

I wanted to check that the top of the grout was level so that there was still contact with the leveling ring after tensioning the bolts and I realised I got a very strange deformation contour. I have attached a snip showing the U3-deformation for two analyses. They are exactly the same except for the change in material stiffness. To the left is the contour for a simulation with the same material stiffness applied to the grout throughout the analysis and to the right is the same contour for the simulation where I've changed the stiffness (increased it) after applying tension to the cable.

Why does this happen?

The stress contours and contact pressure contours seem fine and are comparable between the two analyses. But my bolt forces are significantly higher in the analysis with changed stiffness of the grout. The contact pressure contours also reveal that more of the applied force (applied to a tower sitting atop the T-flange) goes into the bolts rather than relieving contact between flange and levelling ring.

I wish to figure out why I get different bolt loads for the same applied level of loading. The biggest deviation between the analyses (apart from the bolt load of course) are the deformation contours I have attached.

in the unreinforced concrete model, after reaching the maximum force, it should experience failure and no increase in force occurs. Can anyone help?

Hello,

I am currently conducting a modal analysis on a reinforced concrete structure using Abaqus, and I am encountering an issue where all the natural frequencies calculated are negative. The model consists of a concrete slab reinforced with steel bars. Here are some specifics of my model setup:

Despite ensuring the mesh quality and reviewing the boundary conditions, material properties, and element connectivity, the simulation consistently results in negative frequencies. I have checked for common issues such as inappropriate constraints, incorrect material properties, and numerical instabilities but have yet to find a solution.

Has anyone encountered a similar issue or can offer insights into potential causes and solutions for this problem in Abaqus? Any suggestions or guidance would be greatly appreciated.

I'm trying to use CDP model but i only have ultimate strength of concrete how should i create stress strain data sheet

Investigating the role of hypergeometric series in Concrete Mathematics, seeking insights into its applications for combinatorial problem-solving.

Hi everyone,

I have simple one bay reinforced concerete. I am trying to analysis it with Concrete Damage Plasticity model and I want to get the hysteretic curves to compare with the experimental results. Although I can get good results about max and min capacities of the structure, I can not get the pinching effect and rigidity degredation. Can anyone give me an idea how to get pinching in cyclic loading?

Hi everyone!

I am working on ABAQUS model which consists of a reinforced concrete wall and has a cantilevered W-shaped steel beam embedded (see attached picture). In order to make it computationally efficient, I am modeling just half of the full-size specimen. The steel beam is subjected to a cyclic shear loading whereas the wall has its base fixed. I have built the model and am trying to match the output with the experimental results. The stiffness of the connection is more or less matching, but the shape of hysteresis loop is quite different. The connection is failing at the same loading stage as that observed in the experiment. In summary, every other thing looks good but just hysteresis loops are different. When I looked more in detail, I found that results from loading and unloading branches are crossing for some cycles. (Plot for one of the cycles is attached herewith.) I don't know what the reason for this might be. CDP is used for concrete and combined hardening is used for steel for defining plasticity.

I am defining cohesive interaction between steel beam and concrete. (Parameters for cohesive interaction that I am using are: Knn=0, Kss=Kst=32 kips/in2, nominal stress along normal direction=0, along shear1 and shear 2= 0.42 ksi, plastic displacement = 0.1 in.).

Can you please suggest me what may be the reason and what parameters I should focus on to fix these issues?

Thank you in advance.

I modeled a concrete coupling beam in Abaqus using CDP material. The cyclic response of the model does not contain pinching and proper strength degradation. According to suggestions, the best solution is using UMAT for this problem. If you have an example of the UMAT code or some reference that contains a reinforced concrete problem, please notify me.

Thanks.

In order to increase the amount of silica fume in reactive powdered concrete, we have to add calcium hydroxide to concrete.

How many percent of the weight of normal Portland cement can be the maximum allowed increase of calcium hydroxide?

I modeled the 2D frame with OpenSeesPy in a way that the concrete class is variable, there is a distributed load on the beams and horizontal load on only 2 nodes, I analyzed the statics in this way, but I am getting an error in the analysis part.

My modeling steps are very similar to the OpenSeesPy 2D Portal Frame example:

However, while I was doing the analysis using eigen in the example, I did not use eigen. I would like your comments.

import time

import sys

import os

import openseespy.opensees as ops

import numpy as np

import matplotlib.pyplot as plt

m = 1.0

s = 1.0

cm = m/100

mm = m/1000

m2=m*m

cm2=cm*cm

mm2 = mm*mm

kN = 1.0

N = kN/1000

MPa = N/(mm**2)

pi = 3.14

g = 9.81

GPa = 1000*MPa

ton = kN*(s**2)/m

matTag=1

for i in range(0,8):

# remove existing model

ops.wipe()

# set modelbuilder

ops.model('basic', '-ndm', 2, '-ndf', 3)

L_x = 3.0*m # Span

L_y = 3.0*m # Story Height

b=0.3*m

h=0.3*m

# Node Coordinates Matrix (size : nn x 2)

node_coords = np.array([[0, 0], [L_x, 0],

[0, L_y], [L_x, L_y],

[0, 2*L_y], [L_x, 2*L_y],

[0, L_y], [L_x, L_y],

[0, 2*L_y], [L_x, 2*L_y]])

# Element Connectivity Matrix (size: nel x 2)

connectivity = [[1,3], [2,4],

[3,5], [4,6],

[7,8], [9,10],

[7,3], [8,4],

[9,5], [10,6]

]

# Get Number of elements

nel = len(connectivity)

# Distinguish beams, columns & hinges by their element tag ID

all_the_beams = [5, 6]

all_the_cols = [1, 2, 3, 4]

[ops.node(n+1,*node_coords[n])

for n in range(len(node_coords))];

# Boundary Conditions

## Fixing the Base Nodes

[ops.fix(n, 1, 1, 1)

for n in [1, 2]];

fpc = [30,33,36,39,42,45,48,50]

epsc0 = [0.002,0.002,0.002,0.002,0.002,0.002,0.002,0.002]

fpcu = [33,36,39,42,45,48,51,54]

epsU = [0.008,0.0078,0.0075,0.0073,0.0070,0.0068,0.0065,0.0063]

Ec=(3250*(fpc[i]**0.5)+14000)

A=b*h

I=(b*h**3)/12

ops.uniaxialMaterial('Concrete01', matTag, fpc[i], epsc0[i], fpcu[i], epsU[i])

sections = {'Column':{'b':b, 'h':h,'A':A, 'I':I},

'Beam':{'b':300, 'h':500, 'A':300*300,'I':(300*(300**3)/12) }}

# Transformations

ops.geomTransf('Linear', 1)

# Beams

[ops.element('elasticBeamColumn', e, *connectivity[e-1], sections['Beam']['A'], Ec, sections['Beam']['I'], 1)

for e in all_the_beams];

# Columns

[ops.element('elasticBeamColumn', e, *connectivity[e-1], sections['Column']['A'], Ec, sections['Column']['I'], 1)

for e in all_the_cols];

D_L = 0.27*(kN/m) # Distributed load

C_L = 0.27*(kN) # Concentrated load

# Now, loads & lumped masses will be added to the domain.

loaded_nodes = [3,5]

loaded_elems = [5,6]

ops.timeSeries('Linear',1,'-factor',1.0)

ops.pattern('Plain', 1, 1)

[ops.load(n, *[0,-C_L,0]) for n in loaded_nodes];

ops.eleLoad('-ele', *loaded_elems,'-type', '-beamUniform',-D_L)

# create SOE

ops.system("BandSPD")

# create DOF number

ops.numberer("RCM")

# create constraint handler

ops.constraints("Plain")

# create integrator

ops.integrator("LoadControl", 1.0)

# create algorithm

ops.algorithm("Linear")

# create analysis object

ops.analysis("Static")

# perform the analysis

ops.analyze(1)

# get node displacements

ux = ops.nodeDisp(5, 1)

uy = ops.nodeDisp(3, 1)

print(ux,uy)

print('Model built successfully!')

My scrutinizing the literature on MS for decades failed to spot any concrete archetypal or milestone documents or the results of some topical statistical investigation that might support at least one of the repeatedly updated clinical definitions of the disease.

Isn't there some expert in neurology, neuropathology, or the history or philosophy of medicine who feels competent to explain, even lend some helping hand for overcoming, this conceptual deficit?

What justifies the characterization of MS in terms of neurological disorders being disseminated in space and in time?

Hello,everyone.

I am currently dealing with a non-convergence problem during meso-scale numerical simulation of a three-point bending test of concrete using a random aggregate model in ABAQUS, where the material chosen is a concrete damage plasticity model that is embedded in ABAQUS, and the load-CMOD curves obtained are incorrect, with a peak load of only about 60N. However, I got the correct results using the same material properties for the compression numerical simulation. In 3TB the contact between the support, the loading device and the specimen is face to face contact.

Please advise me what I should do next to modify the model?

The purpose of earthquake engineering is not to build strong and earthquake-resistant buildings that do not experience the slightest damage in rare and severe earthquakes. The cost of such structures for the vast majority of users will have no economic justification.

Instead, engineers focus on buildings that resist earthquakes' effects and do not collapse, even in severe external excitations. It is the most important goal of international standards in the seismic design of buildings.

Below I have mentioned some crucial points in reducing the seismic demand in reinforced concrete structures. If there is anything else that is not on the list, feel free to append:

1- Selecting suitable construction conditions with the desired soil type of seismic design

2. Avoid using unnecessary masses in the building

3- Using simple structural elements with minimal torsional effects

4. Avoid sudden changes in strength and stiffness in building height

5. Prevent the formation of soft-story

6. Provide sufficient lateral restraint to control drift through shear walls

7- Preventing disturbance in the lateral behavior of the structure by non-structural components

I'm doing a research on numerical investigation of behavior of steel concrete composite beams. I'm using the Abaqus software in my analysis. In my model, I'm using shell element to model the Steel beam and solid element to model the concrete slab where the reinforcement has embedded in it. The steel beam and the concrete slab is connected using the shear studs which were modelled using solid elements. My question is, If we use a tie constrain in between the steel beam top flange (modelled with shell) and shear studs (modelled with solid element) what would happen to degree of freedom in rotation of the steel beam? Here I have used a tie constrain to simulate the welded connection between the steel beam top flange to the shear studs. Will ABAQUS automatically constrain the degree of freedom in rotation if I use this interaction? If so will it cause any inaccuracy in the final results?

Also, is there any possibility to use shell to solid coupling to simulate the same interaction?

Which mixing approach is the best for producing recycled concrete ? in term of performance, cost and time ?

1/ What is the effect of using sea water on concrete? 2/ What are the ways to protect concrete from seawater?

Hi all! I am trying to understand the stress vs strain plot for my model. I am using Abaqus/Explicit so 'LE' is the strain that I selected for output. I am trying to understand the trend of stress vs LE plot. Why am I getting opposite that expected? Can anyone please help me to understand this? The loading and unloading branch are mirror image of what I am expecting. Also, why I am getting positive strain?

Hi all! There is an optional feature in Abaqus to define a concrete failure point by going to 'edit keywords' and adding '*concrete failure' for concrete damage plasticity model. Can anyone please explain it to me what will happen if this concrete failure point is added and what if it's not added? I know it is also essential to trigger element deletion but looks like it's inclusion is changing the output results not only the visualization.

Due to PPC, the strength gain of concrete is slower at the early stages. While OPC should gain strength of 65% of 28 days strength at the end of 7 days. Whether 45-50% strength is gained by PPC concrete after 7 days of water curing. Is that OK? Is there any reference code available to justify the statement?

What is the meaning of the AFt phase in cement concrete?

Is the number of passes to control the quality of compaction too extensive?

Please consider the problem, seriously, with concrete examples or evidence.

Hi ResearchGate world!

I am looking for a package in R to statistically compare the concreteness level of two words (e.g. huge vs tiny). I see that the R package 'doc2concrete' is associated with the database offered by Brysbaert and collaborators in which the participants told the concreteness level of 40000 English words. The authors provide in their database the mean concreteness level of each word along with the standard error of the mean and the number of participants who answered that question.

R package 'doc2concrete': https://cran.r-project.org/web/packages/doc2concrete/index.html

Article Concreteness ratings for 40 thousand generally known English...

See Electronic supplementary material( doi: 10.3758/s13428-013-0403-5)

With these data, I can do a Student's t-test comparing the concreteness score of two words. However, although this information is in the database, the package only seems to offer the mean of the level of concreteness (i.e., without the number of ppt and the standard error), so the statistical comparison cannot be made directly (of course there is the option to get the information I need in the databases and do the student t's in R, but I am looking for R to be able to access that information directly).

Do you know how I can do this with this package or another package in R?

Thanks!!

If there is overdosing of admixture then there is chance of segregation,shrinkage and other many problems and company also only provides dosages as 0.5-1.5% of cement in their certificate so how can we know the exact dosage of admixture for concrete??

After several trials 1% of admixture is fixed and in such case can we put 0.6% admixtures in starting time and remaining 0.4% after sometime(maybe 2hrs later) such that workability of concrete remains good for longer time. Actually i want to clear can we put admixtures two times in a concrete?

I have unconfined concrete cylinder test data of stress vs strain. I need to do abaqus modeling for confined concrete using Drucker Prager. However, the literature I am referring to just says that it implemented a "hyperbolic Drucker–Prager" yield surface. I am searching through the literature and most of them have formulas for "Linear Drucker–Prager". Can anyone help me in this process or guide me to literature that has a hyperbolic Drucker–PragerDrucker Pragerformula that can help me convert my unconfined concrete test data to confined concrete Drucker Prager model with a hyperbolic yield surface?

Does gamma radiation have a destructive effect on the microstructure of concrete?

What aggregates are used for protective concrete in your country ?

Dear Sir,

We all know that the water cement ration 0.45, which may vary due to the Mix-Design. But during the concrete due to changes of weather & materials SSD condition the slump changed (Generally Dropped) in mid time.

So looking the help from experience person, how many water may use for 1mm/5mm slump gaining. The equations also okay, I can check with our mix-design for getting the value.

Thanks in advance for your assistance.

Is it possible to analyze and design an inclined or slanted concrete column on a concrete beam in the ceilings of the eighth and ninth floors of a ten-story building using ETABS software?

According to the ACI Code stiffness modifiers (modifiers used to reduce the moment of inertia) are used for each structural elements for example 0.7 for columns and 0.35 for beams...

For those who do seismic and/or wind design according to Eurocode where are these modifiers used and if they are not clearly available like in the ACI Code how does the code apply these modifiers ? does eurocode use a coefficient to reduce the compressive strength of the concrete instead of using these coefficient?

I am currently working on a model which has steel beam whose one end is embedded in a concrete wall. The cantilevered end of steel beam is subjected to cyclic shear load. I am struggling to model the interaction between the portion of the steel beam embedded and the concrete. What will be the appropriate way to do it?

I tried by using 'hard' contact in normal direction and using coefficient of friction of 0.45 along tangential direction. The results obtained are different than experimentally observed.

Now, I am thinking of using surface based cohesive interaction, but I don't have necessary parameters which is needed for defining traction-separation and damage. Is there is a rational way to calculate these parameters without doing experiment?

Any suggestions and help will be appreciated.

Hello everyone,

I am conducting an isotherm/kinetics experiment to measure the capacity of a concrete filter/pervious concrete (a filter made of concrete) to remove heavy metals.

My question is, how can I measure how the percentage of the heavy metals removed is due to chemical precipitation and how much is due to the adsorption of heavy metals to the concrete filter?

Please take a look at the picture attached to see the concrete filter.

Please consider the following conditions:

The filter leaches Ca and carbonate, so precipitation happens.

The pH is constant at 12, and I cannot change it.

The adsorbent is in a filter stape as attached and is not in powder form. So, a part of precipitated heavy metal ions are trapped inside of the filter.

The picture has been extracted from Holmes et al. 2017 (Enhancing the Ability of Pervious Concrete to Remove Heavy Metals from Stormwater).

Hello everyone,

I'm simulating the axial compressive behavior of both circular and rectangular CFSST stub columns. Things went fine with the circular section but the opposite applied to the rectangular section as the solution didn't converge and not even reach at least my desired applied load (displacement control)

I used both C3D8R element for both steel tube and core concrete with contact property as follows:

Tangential direction: Penalty method with 0.6 coefficient

Normal direction: Hard contact (allows for separation after in contact)

The effect of corner region of the steel tube is also considered by partitioning the steel tube into multiple parts (See figures below). I tried both static general and static riks but none of them converge with the step time increment of:

initial increment: 0.001, minimum: 1E-20, max: 0.05 (or even smaller such as 0.025)

Please help me out guys. I'm really desperate for this problem.

For instance, the cylinder strength at 7 and 28 days exceeds that at 56 or 90 days.

We need modern methods and new management of rivers and streams on low drainages and low levels due to the change in the river’s regime and the nature of its course, and methods and studies in the same river, whether making submersible dams made of capillary or concrete, lining and narrowing the section of the river with dirt or stone, or lining it with concrete, concrete lining, or other methods. Because the river at this section is nothing but a swamp for sedimentation and evaporation

We need modern methods and new management of rivers and streams on low drainages and low levels due to the change in the river’s regime and the nature of its course, and methods and studies in the same river, whether making submersible dams made of capillary or concrete, lining and narrowing the section of the river with dirt or stone, or lining it with concrete, concrete lining, or other methods. Because the river at this section is nothing but a swamp for sedimentation and evaporation

I need some one to help me to do compressive strength analysis on concrete cube using APDL Ansys

I have some issue during analysis. The results of software aren’t same the experimental. I need to have some information about the boundary conditions and the unit of dimensions and stress in APDL is it in mm and MPa or different.

Hello... Is there a concept that stipulates that the increases obtained in the flexural or tensile test results must be higher than the increases obtained in the compressive strength assuming the use of steel fibers in a fixed ratio for geopolymer concrete with the reference mixture and adding a specific nanomaterial to it, or could it be less?

How can I effectively model the interface between two sequentially cast layers of Normal concrete in Abaqus, where the first layer (20cm thick) is cast, and the second layer (5cm thick) is poured within an hour before the initial setting of the first layer? Additionally, should I simulate stages of curing and hardening for the Normal concrete material, or is it sufficient to address this through material interaction modelling?

Is it more than a coincidence that some fields are dominated by rationalists while others are dominated by empiricists? Maybe the rationalists dominate fields that require more abstract thought. While empiricists dominate the fields that require more concrete thinking.

My complete opinion:

I am performing a bond test of concrete with metals. Most of the literature reviews that I have looked so far refer to the ASTM C234-91-a. This standard was withdrawn in 2000. However, many research papers and journals, even after 2000, are following the methods in C234. I am looking for ASTM C234 or any other suggestions for standards for doing a pull out / push out test of metals on concrete.

Thank You,

Dear Researchers

Kindly comment on the problem I am facing during titration.

To quantify chlorides ion in concrete, I prepared the sample following ASTM C1152. The chlorides were extracted from 10g concrete powder and the concrete I am testing is composed of OPC or FA/GGBS blends (FA/GGBS blended concrete is a geopolymer concrete with various alkali concentrations).

Now the problem is, when analyzing concrete samples, EP point was not detected but when analyzing blank sample (without concrete and with 2 ml NaCl) the EP point was detected at around 1.98 - 2 ml AgNO3 volume. I repeated the test atleast 10 times both on concrete and blank samples, each time the result is same.

What could be the possible problem? I am following the steps mentioned in the standard. since the blank titration was accurate, I assume there is no problem with titrode or machine.

One more thing I want to mention is, I successfully found EP for sample extracted from FA/GGBS geopolymer concrete activated by low Na2SiO3/NaOH ratio activator, where NaOH concentration was 8M.

Additional information: I am using Metrohm titrator and titrode is Ag with AgCl coating. Sulfides were not removed by oxidation (yet I was able to find EP for geopolymer concrete activated by low Na2SiO3/NaOH ratio activator, where NaOH concentration was 8M)

Kindly share your opinion so that I can rectify the methods I am following.

Thankyou in advance

#chloridetitrationn