Questions related to Reinforced Concrete
I'm doing a research project on progressive collapse. I was able to apply a controlled displacement of 1100 mm to the central column of a reinforced concrete frame, I obtained the force-displacement curve of the model but when comparing it with the curve of the experimental test of the IMF specimen, I found that the force of the model was the double the test force. I don't know if I'm making a modeling error. I am using ABAQUS software and my analysis is quasi-static. I used the Smooth Step amplitude type but I'm not sure what values to put in Time/frequency and amplitude to achieve a displacement of 1100mm at an application speed of 0.416mm/s.
I am doing Finite Element Analysis of spirally reinforced concrete columns on ATENA 3D. I am perplexed while defining the spiral reinforcement as there is no option available for it. So far what I have understood is I need to define joints for spiral then connect them using line segments. For this option, I need to calculate the coordinates of joints manually, which is surely a hectic. If you can help me then please do.
I am used to using ANSYS. My students use ABACUS. What do you think is the most popular and the easiest to model concrete elements.
I am trying to simulate blast loading on reinforced concrete bridges using time history by SAP2000 or CSI BRIDGE. have anyone tried that or check the validation of SAP2000 to analyze the blast loading by comparing results with any other software like (ABAQUS , ANSYS , LS-DYNA .......)
I am modelling a beam reinforced with GFRP bars on ATENA 2D. The experimental and analytical load-deflection behaviours are in agreement with each other however, my FE model terminates 10 KN before the experimental load due to stress concentration near to loading plate. I tried to avoid it by increasing the plate's surface area but it didn't work. Please guide me on how to prevent stress concentration.
In wide RC beams, the shear reinforcement (stirrups) are distributed along the beam length and across its width. There are limits for the longitudinal spacing of stirrup legs (SL) in the current Codes of Practice. But, Do these Code have provisions for the stirrup legs spacing in the transverse direction (Sw) of these wide RC beam? Only EC2 Code deals with Sw, where it assumes that Sw = SL = 0.75d.
I' researching the progressive collapse. In summary I want to see what happens if I apply un displacement controlled de 1200 mm under a reinforced concrete frame to simulate the loss of one central column. i.e I want to redo one model of this paper (usefi et al, 2016). Specifically this model: model.png (see atachments)
I already have my model, but it doesn't give me the correct results as in the paper. this is the model i made: mymodel1 and mymodel2.
as you can see, the results are no logical . I apply a downward load but it gives me positive displacement. and it seems that there is some problem with the analytical surfaces I think I'm making basic mistakes, because I'm not sure if I'm applying the loading speed correctly.
Any suggestions please?
I monitored some concrete samples that had reinforcement steel bars embedded in them. The samples were put in a solution of 5% sodium chloride to simulate exposure to chloride in marine environments (Coastal cities, Off-Shore buildings , etc.)
After I got the Nyquist curve and Bode plot, I want to fit the curve with an equivalent circuit. My question is how to decide what elements to use and what arrangement of such elements is the best?
I'm using the Gamry Potentiostat and has the Gamry software (Echem). I see that the software provides some typical circuits to start as well as having a model editor.
I attached an example of a Nyquist and Bode plots that I got as well as an illustration of the sample setup.
I have an answerable question regarding a reinforced concrete model with a monotonic load applied.
As shown in the attached image, there is a difference in the curve.
I think my model has no stiffness degradation in the plastic phase.
What are the factors and parameters that affect this and how to calibrate the model?
thank you very much .
Hello i'm doing my research on hyperbolic Reinforced Concrete cooling tower
i'm searching for a model to use it as my main model and i can verify it with another article but i can't find a complete one that Gives all the detail and the model should be new cooling tower
cause the vgb guild line or other designing codes may have changed over the years.
model should have the function of shell
Radius of different heights
and the measurement of columns and number of them
i'm totally destroyed on this problem
hope someone can help
I am running a model of concrete SOLID65 with LINK (bar) elements.
I have attached below my material properties and failure criteria.
The model has not converged yet.
Any tips on how to make the model converge?
I'm looking for referenceable information on the breakdown of buildings by primary structural support in the UK or EU e.g. Loadbearing walls of masonry, loadbearing panels, loadbearing frame and modular. Ideally also broken down for each year.
With the introduction of the latest version of the ACI-318, what are some of the impacts to design as well as organizational changes that this new document will pose?
As far as FRP is concerned, there are two documents in North America for the design and detailing of RC structures, i.e., CSA S806-12 and ACI 440.1R-15. I have been trying to find any similar documents in Europe but it seems there is no unified European document so far. Any clues?
If you were to strengthen concrete elements, which would you prefer? Reinforcing concrete elements with FRP rebars? How about coating the concrete with FRP jackets to strengthen it?
I am performing strengthening of the reinforced concrete beam using Carbon Fibre Reinforced Polyme (CFRP) strips with different strip widths placed at different intervals along the span of the beam using ABAQUS? What procedure and parameter should I use?
I am modelling a steel fibre reinforced concrete beam in Abaqus. I will be using the concrete damage plasticity(CDP) model. I have obtained the engineering stress-strain data from experimental tests. Now, when calculating the damage parameters and inelastic strains, do I need to first convert the engineering stress-strain curve to a true stress-strain curve?
GEO-GRID WITH POOR ELASTIC MODULUS AND BOND STRENGTH;
Those who defend the design principles of reinforced concrete members produced with the use of geogrids are academics who are far from the basic principles of reinforced concrete. Would they live in the buildings to be built with Geogrid? Even the structural performance of corroded convetional reinforced concrete members are better than those used geo-grids.
How to reduce the initial stiffness in a reinforced concrete model in Abaqus?
I have modeled the concrete with "CDP" and shear connectors are embedded in the model.
Thank you very much in advance!
So If a column isn't casted exactly in the intended location according to the structural drawings, and the centre of this column is moved 3 cm away from it's original location.now in the ACI code, accidental eccentricity is taken into account in the column design equation,so the question is how to check If that eccentricity is within the allowable range? According to the ACI?
I made a numerical model of a reinforced concrete frame in ANSYS APDL software in order to perform a PUSHOVER analysis, but the only experiment results that I got from the literature are obtained from a cyclic load experiment. However, the results are illustrated in terms of Base reaction versus roof displacement.
My question is, can I validate my numerical model with the envelope of the experimental cyclic results?
For example, one of the most related papers has been brought at below:
Wu, Jie, and Michael D. Lepech. "Incorporating multi-physics deterioration analysis in building information modeling for life-cycle management of durability performance." Automation in Construction 110 (2020): 103004.
In general, if we want to use the auto assign hinge in SAP2000 or ETABS, in the box shown in the second figure, what load combination or load case should be used for time history analysis?
Hello fellow practitioners. I Have a quick question please. I am currently verifying the resistance of a column that is reinforced with different type of steel. On the edges we have a total of 12 #6 bars with a yielding stress of 275 MPa. in the center of the column we added one #18 bar with a yielding stress of 517 MPa. I tried to find the answer on the code. But it doesn't discuss how to calculate Mr when the yield stress of steel is not uniform.
These attached figures are captured from Concrete Frame Design Manual using ACI-318 attached with Etabs Design examples.
It calculates the amplified moment due to second order effects using this equation:
, not by the equation proved in all stability books
I tried a design example in Etabs to verify this and I found that it does use the first equation.
For finding the behavior and effect of corrosion in the simulated specimens at a particular location. If the real stress generation due to corrosion with passing times are known at a particular location.
If a reinforced concrete beam is being tested under four-point bending. What would be an appropriate loading rate for the actuator if the applied load is load controlled.
What is the minimum socket depth for designing column-foundation connected by socket ? (Commonly used for precast concrete structures and the joint is filled with grout)
I am research scholar at SVNIT, Surat, India and working in the field of Design of Reinforced Concrete (Industrial) Chimney. I need a minimum of 5 international reviewer from academics for my research paper titled as "Moment-Curvature Relationships for RC Chimney Sections". In this paper moment-curvature diagrams are plotted using three different design standards namely IS: 4998 - 2015, ACI: 307 - 08 and CICIND 2011 and results are compared in terms of strength, ductility and energy absorption. Please let me know if anyone can review my paper.
In the pull-out tests, the rib face angle of steel bars is one of the important factors. Is there any paper or brochure that provides information about rib face angle of steel bars?
For example, I want to know what is the rib face angle of the 16 mm steel bars.
Are You by any chance familiar with any data/papers on the subject of RC or prestressed circular hollow sections (in columns, beam-columns, beams) subjected to preferably both axial force and bending moment or maybe under pure bending at worst. If Yes please share the links in the comments below.
I am interested mostly in experimental research but numerical analyses would also be appreciated.
I am simulating a reinforced concrete beam with CDP model under four points bending test. However I keep encountering negative internal energy issue and wonder what might be the problem causing this.
I am using dynamic explicit step with default mass scaling and time period of 1. Also, displacement load of 20mm and mesh size of 15mm.
Thanks for you help in advance.
Since Bond Slip Behaviour is about the project I am doing right now. I wanna know are there any method or technology to prevent the Reinforced Concrete from the occurrence of Bond Slip Behaviours
How I can plot the bond stress between the reinforcing concrete and steel, I use the
CONTACT 178 elements in the bond and in the other example the COMBINE 39.
You find the file below.
I want to analysis a beam under fire condition by developing a code based on finite element method (FEM). I have some problem with calculation of axial force in the beam due to temperature change. Do you know a good source which has explained the algorithm in detail?
I want to model steel fibres reinforced concrete beams in Abaqus, but I don't know how to model it. currently, my little research on the internet showed that I don't need to explicitly model fibres in concrete but I need to take fibres into account in the stress-strain curves.
Now please tell me that along with the stress-strain curve of FRCB's, what other parameters do I need in order to completely model FRCB's.
My SOLID65 element is reinforced concrete but what modulus of elasticity and material properties do I put? For nonlinear analysis
I need to perform a delamination test in abaqus to observe the cracking in a composite reinforced concrete specimen, should I use the concrete damaged plasticity and its parameters? and if so, can someone provide an example of these parameters so that i can use them for a try. thank you .
I'm going to analysis of theorical RC beam by FE nonlinear analysis then verify the RC beam models with FEA softwares.
I try to model a reinforced concrete coupling beam, as the push of cyclic response doesn't fit the experimental data, I modeled a cylindrical specimen under cyclic compression loading to observe the damage parameters efficiency. As per articles, the response push has to intersect the material data, but It doesn't happen. What is your idea about the results? Does the output method is correct (see the attached image)?
In the seismic design phase of reinforced concrete buildings infilled with masonry either by brick (solid or hollow) or by concrete block (solid or hollow), with the existence of shear walls, we need to know the appropriate value of the behavior factor for this interaction of systems.
My question is what is the value to be taken for the behavior factor in case of seismic analysis of this type of buildings to evaluate their seismic response according to the famous world seismic codes.
Wind energy has been established as the most profitable and tested energy since ancient times. It was first used on sailboats since ancient times, followed by windmills. Today it is included in "clean" energy sources, as they are commonly called non-polluting energy sources. A large part of the cost for the construction of a wind turbine is its support on the ground. Large wind turbines need huge reinforced concrete bases that use the same weight to prevent the wind turbine from overturning, which receives very large gusts of wind. There are wind turbines where their base consists of 2000 cubic meters of reinforced concrete. That is, they weigh 2000 m3 X specific weight of reinforced concrete which is 2450 kg / m3 = 4.900000 kg or 4.900 tons The cost of reinforced concrete in the mountains exceeds 300 euros per m3 That is, the cost of the base is 2000 m3 X 300 euros = 600,000 euros. If you put in the excavations, it is very expensive. In order to reduce the cost of support but also the cost of electricity, as well as the pollution from the manufacture and transport of concrete, the concrete base must be removed and replaced with deep ground anchors like that of the patent which I hope is the strongest anchor worldwide. The cost of support with my patent of this particular wind turbine of 2000 m3 will not exceed 80,000 euros.
We intend to use a sensor based machine to determine the residual strengths of corroded reinforced concrete.
I am looking for a company that produces a mesh / fabric made of hemp fibers, which I could use as a strenghtening for reinforced concrete elements. I would be grateful for any information.
I am trying to model interaction between longitudinal reinforcement and surrounding concrete using 2D-FE available in ABAQUS package as shown in attachment.
The model was defined as 2D Plane Stress. The concrete beam was modelled using CPS4R element whereas the reinforcing bar was modelled using truss element T2D2. It is important to mention that the truss element was created by using 2D Deformable Wire.
In some published articles (See below), I found that using Cohesive Element (COH2D) is possible when using wire as a reinforcing bar. However, none of the authors explained how the interaction was created between reinforcing bars as Wire (T2D2) and Concrete beam by using cohesive element.
It was not clear whether they have divided the concrete block into two parts to define cohesive element and reinforcing bar in between or kept it as one block and embedded the reinforcement into concrete.
Have any of you tried to use cohesive element to define interaction between concrete and reinforcing bar in 2D environment, especially Wire as a reinforcing bar and CPS4R as a concrete?
Published papaers where COH2D was employed.
I want to calculate the nominal moment capacity of some reinforced concrete beams in Etabs. I have designed these beams by section designer in Etabs.
I would really appreciate that if anybody could help with with this question.
I'm modelling a steel beam to reinforced concrete column joint in Abaqus/standard. I use concrete damage plasticity model for concrete modelling, but I don't know what value should I input for dilation angle? Does anyone have information about this? And the other hand, what about viscosity parameter? Does it make a problem if I take "0" this parameter as Abaqus user manual default?
Hello to everyone
For the early-age cracking behavior of continuously reinforced concrete pavement placed on a lean concrete base, how the values of normal stiffness and shear stiffness can be defined using DIANA software with a non-linear elastic friction model?
I am modelling concrete beam strengthened with FRP fabric in pure flexure zone on ATENA 3D. How can I define a material property for my FRP fabric? I am modelling the fabric as a macro-element then assigning property to it. I am confused about which material model should be used. Model associated with reinforcement offers the input of user-defined stress-strain curve, but it can't use in macroelements. What should I do? Please advise.
Ahsan Parvez in his paper modeled the confined behavior of HSC columns confined with HSS using built in material model CC3NonLinCementitious2 (User) along with Attard and Setunge stress strain curve for confined concrete. Apparently ATENA 3D don't give option fort stress strain curve in built in model, how the author carried out it? I am stuck in modeling softening part. In the pic, series 1 is exp curve, series 4 is atena result without transverse reinforcement, while series 3 is with transverse reinforcement. Please help.
I would like to consider corrosion in a column in my numerical simulation in ABAQUS? Can I just decrease the stiffness to simulate the corrosion? or any change in mechanical properties?
Is there any reference or paper or guideline about numerical simulation of corrosion specially in the steel or RC columns?
I modeled a SFRC coupling beam in the Abaqus using CDP and the response for lateral load-displacement is achieved as in the attached picture. Is this response acceptable? (The f'c of the model is 56 MPa)
The main problem is that I can't get the pinching on this graph. How is it possible to have the pinching on the Abaqus output?
What my understanding is lateral reinforcement will apply the confinement pressure by it self as the core concrete dilates; therefore, the modification in the concrete model not required. In the theory manual of ATENA, it is given that there is CC3DNonLinCementitious3 for confinement sensitive case; however, model with this name is nowhere while defining the material.
The orange one is experimental while blue is as predicted by ATENA 3D.
I want to know the best software to form a controlled crack in a concrete beam.The beam has different concrete grades.
I need a researcher who can simulate three-point flexure tests for 13 specimens of reinforced concrete beams. He would co-author a paper with me being published in Elsevier.
Dr.-Ing. Nazim Nariman
A practical mathematical way to find the cubic meters of reinforced concrete in small structures is to multiply the number 0.245 by the floor area and the result shows the cubic meters of the structures (without the bases) Floor 100 sq.m. X 0.245 = 24.5 cubic meters. The specific weight of reinforced concrete is 2450 kg / m3 The 24.5 cubic meters X the 2450 kg = 6025 kg or close to 60 tons. A floor of 100 sq.m. only its concrete 24.5 m3 weighs 60 tons. Each cubic meter of reinforced concrete has a steel reinforcement of approximately 140 kg / m3 The 24.5 cubic meters of the floor of 100 sq.m. X 140 kg / m3 = 3430 kg of steel the floor of 100 sq.m. One of the thousands of prestressing steel available on the floor, with a cross section of 20 mm, has a lifting capacity of 63 tons. That is, a single steel raises the floor in the air, while in an earthquake the construction presents problems. Why so much waste on steel, and why do earthquakes fail?
Answer. Seismic loads triple the intensities But this steel reinforcement is excessive even for a large earthquake. And yet, construction fails easily in a major earthquake. What's wrong? I will give answers to this big question below. Above I mentioned the tensile strength of steel. However, a reinforced concrete structure is also made of concrete. The compression concrete specifications are very good. It does not have good standards for all other forces such as shear, tensile strength. For example, the specifications of concrete in compression are 12 times stronger than in tensile strength. In reinforced concrete, steel and concrete work together with the mechanism of affinity. The cooperation between concrete and steel is achieved through the mechanism of relevance. When we say the mechanism of relevance we mean the combined action of the mechanisms which prevent the relative sliding between the bars of the steel reinforcement and the concrete that surrounds them. The mechanism of the connection consists of the adhesion, the friction and in the case of steel bars with embossed shape, the resistance of the concrete which is trapped between the ribs. The combined action of these mechanisms creates a radial development of shear stresses applied to the concrete and steel interface. When these stresses reach their limit value, the relevance is destroyed, by breaking the overlay concrete along the steel bars, and detaching the steel from the concrete. .
Shear stresses are created on the interface of the two materials. . The question is whether the concrete withstands the strong shear stresses imposed by the tensile strength of the steel; No it can not withstand and for this reason we have the pulling or otherwise slipping of steel through the concrete, and the destruction of the coating concrete around the steel. Conclusion 1) The premature shear failure of the coating concrete cancels the ability of the steel to tensile, because it does not manage to take on the tensile loads it can, because the cooperation wants two. Conclusion. The coherence mechanism is at least insufficient for these two materials. That is, if you put steel in butter, there will never be cooperation because butter does not withstand the pull of steel. If you put more pieces of steel in the butter or concrete you will have greater strength; Is it a Question? Solution There is also the concrete-steel co-operation mechanism of the prestressing which imposes compression on the concrete cross-section to equalize the tensile stresses that the affinity mechanism would receive. There is no steel-concrete connection in the prestressing mechanism, so the shear failure is non-existent. The prestressing mechanism strains the concrete only with compression which it can withstand because it can withstand 12 times more compression than it can withstand tensile stress, and it strains the steel only with tensile strength in which it is awesome. Even the protruding walls have a high rigidity, ie a small deformation, so they do not transfer deformation to the trunk of the beam with which it is connected to it at the node. Other causes of the relevance mechanism that pre-tensioning solves are as follows. A reinforced concrete wall, when its trunk is bent, one side is compressed and the other is stretched. That is, one side shrinks and the other grows. There is a point in its cross section where compression and tension have the maximum force. This point is the critical failure area. This point is responsible for the brittle failures of the structures in the earthquake. If we stop the bending of the wall we will eliminate the critical failure area. Is there a design method to stop the bending and the critical failure area? Yes there is. As we said the stretching side grows. If, with an unrelated tendon, we apply transverse compressive forces to the highest level of the cross-section of the wall side, greater than the tensile forces, then we have stopped the bending and the critical failure area. One problem was solved. Well now we have a rigid wall in terms of lateral earthquake strength without critical failure area. Like a rigid wall that is, its overturning moment will be transmitted through the nodes where it is connected to the beams, on their logs and after bending them easily as rigid as it is, it will break them. Another problem? There is a solution? Yes there is. If the protruding unrelated tendon that stops bending does not stop at the base foot of the wall, but extends and anchors into the ground, then the forces of the earthquake are deflected into the ground. The knots will not present great torques, capable of breaking the beams. For this reason I do not join the base of the sole with the ground but I join the upper ends of the sides of the walls with the ground with tense tendons without relevance. The reason is that with this method I stop both the torque of the nodes coming from the bend, and the critical failure area of the wall. The critical failure area of the walls is created in the cross section of the wall which is close to the base. This creates a potential difference in the adhesion of the reinforcement and the concrete. With the method of the invention, the tense unrelated tendon which is both embedded in the ground and the upper end of the wall, there is no potential difference or critical failure area. The problem of deformation with fringe failures is solved! In addition, the application of compressive stresses to the wall cross-section succeeds in increasing the cross-sectional strength of the developing floor and base intersections, increases the active cross-section, improves the sloping trajectories, and reduces cracks. The ground anchor mechanism increases the strength of the ground so that it can accept higher compressive loads. .
Why do we install steel reinforcement joining the construction of the beam and the slab with the balconies? Answer In order not to overturn. I do the same. I join the upper part of the wall with the ground so that it does not overturn in the earthquake ................................. ..............
. 2. Why do we apply prestressing to very large openings instead of simple steel reinforcement? Answer Because prestressing reduces flexion, and increases active cross-section. This is what I do to reduce the bending of the walls ...........
Why do I want to reduce the bending and torque of the walls? Answer Because the walls are connected to the beams and any change in the vertical position of the wall deforms the beams as well. The bending of the trunk of the wall and their overturning moment are the factors that break the beams and fall If we stop the overturning moment and the bending of the wall, how will the beam be deformed? .
The concrete damage plasticity (CDP) model can predict the hysteresis behaviour of RCC structure and it is mostly used in Abaqus FEM software. This CDP model is good for the visualization of plastic deformation/localized crack pattern. It is also good for confirming the peak value of each hysteretic cycle but the basic bond-slip behaviour is not noticeable in the output of the result when the CDP is used. This is why the actual energy dissipation area/boundary is not identifiable in the present state of the CDP model. So considering this issue, a new model like CDP is needed to be adapted where it is applicable.
Obviously, it is impossible to use continuous reinforcement concrete bars; thus, several splicing methods are available to tackle the problem. Among them, overlap with tie wire, coupling, and welding methods are the common ones.
The question that has been on my mind is: What is the force transmission mechanism difference between these methods?
In the overlap splicing method, there is inherent space between the center of the bars. It means that there is a discontinuity in force transmission in this method. On the other hand, in mechanical splicing (coupling), the rebars' center is in precisely the same direction. Several tensile tests in this method have shown us that the rupture will never happen in place of the patch (beneath the coupling). While in the overlap splicing method, a fracture could occur anywhere along the rebar.
The question is that, has the force transmission mechanism taken into account for splicing rebars? Or overlap splicing method exists just to keep the rebars in their place for concreting?
Because the mentioned methods are acting quite differently in terms of the force transmission mechanism.
Thank you so much for your attention and participation.
I tried modeling a simple 4 point bending test in Abaqus, but unfortunately, the load-displacement curve was ascending and the crack and final load didn't match the experimental data. I used embedment for reinforcements and tied the supports to the beam. The load applied to the reference points which are coupled to the cylinders tied to the beam. I used different kind of steps like static general, dynamic explicin or dynamic implicit but the outputs was close to each other. Do you have any suggestion to solve this problem?
The objective is, based on the impedance signature data of a concrete beam in operation, to define when a new obtained signature will represent a normal state of operation or if a local inspection will be necessary. It is known that, in the condition of normal operation, the beam is subject to several environmental phenomena (temperature, humidity) and phenomena of the operation itself (static and dynamic loads, for example). All of these phenomena influence the impedance signature. Shall we discuss about this?