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# Bridge Engineering - Science topic

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Questions related to Bridge Engineering

While estimating the contraction and local scour, there are many equations in the literature mostly produced by using prismatic channels (e.g. rectangular). However, in real case studies, we are modelling the rivers with their irregular cross-sections and for scour analysis, the approach channel depth or flow depth at just upstream of the bridge could be "Maximum flow depth", "Local flow depth" at the upstream face of pier, and "Average flow depth".

The question is which approach should be used for contraction and local scour?

For contraction scour the answer is most probably the "Average flow depth".

What about the scour around piers?

i have vibration data of bridge and process the data with different possible techniques such as FFT, Wavelet decomposition, Empirical mode decomposition, Hilbert Transform, Frequency domain decomposition, spectrograms, etc. but still i am not able to locate exact or pin point frequency of the bridge structure. in the following techniques the results are in a specific range of frequency such as 2.6 to 3.1 Hz. The data showing this specific range and not providing the exact frequency. because in this range any number can be the natural frequency of the bridge structure. so the actual frequency lies in this specific range but i want to go further in depth to figure out the exact value of the frequency in Hz. but the problem is i am not able to find any technique that will give me answer of my curiosity. i recorded data from accelerometers considering normal traffic conditions. there is not closure of bridge. vehicles are passing normal situation.if anyone have any clue about it or still my question is not clear so i can explain further

i attached some of my results

i will be very grateful to anyone who let me find my answer

thanks

Hi All,

l am modeling a composite slab on girder bridge on ANSYS APDL following the shown procedure.

I connected the shell element slab to the beam by using MPC184 rigid links.

All of my elements have 6 degrees of freedoms (compatible) and it's a linear static analysis.

I am applying a lateral force in the Z direction along the bridge parapet/railing.

Self weight / gravity is not added.

The nodes from all elements match and the meshing seems fine.

Its a simply supported bridge (roller on one side and hinge on the other)

The deformed shape of the bridge under lateral loading looks okay. But the reaction forces do not make sense. I change the location of the force laterally and the reaction forces do not change.

I glued the areas/lines before meshing.

What could possibly be wrong? I see it as a connectivity error but am not sure where I went wrong

What is the shell orientation mean in ANSYS APDL?

Does it mean that if I have a shell on the XZ plane then I set the orientation as 0 degrees as shown in the pictorial view

and if I have a shell on the XY plane then I set the orientation as 90 degrees?

Or does it mean something else? Like the direction of the fibers in the material?

I am modeling a bridge on ANSYS APDL using shell and beam elements. The beams and slab are connected using MPC184 (constrained element).

After I am done modeling and meshing I merge nodes with 0.001 tolerance yet I still get an error saying meshing will produce errors. even when i tried to merge all I still get a warning / error message

After Nummrg,all / Nummrg,NODE .... future commands which depend on the node to solid model connectivity (meshing, mesh, clearing, solid boundary condition transfer, etc.) may not operate properly.

My results are wrong. Is there a step that I messed?

I am not sure whether to use boolean A glue command to glue the areas / lines of my model together.

OR

just use merging nodes NUMMRG, node command

My model is a static linear bridge element where the slab and railings are shell elements, the beam flanges are beam elements and the beam web is a shell element.

Beam and shell elements are connected using MPC184 rigid links.

Hello!

I am analysing a cable stayed bridge seismic behaviour in Ansys Mechanical APDL, but I have got some problem unfortunately. I wolud like to run multiplie loadsteps in one work session. In every load step I want to prestress a pair of cables so that the other ones are stay prestress free. Every cable in the structure made of LINK 180 element. Here is the snipet of my code where I defining the loads and loadsteps and try to solve them.

!MEGTAMASZTASOK

!///////////////////////////

ALLSEL,ALL,ALL

NSEL,S,LOC,Y,15

NSEL,A,LOC,Y,-15

NSEL,R,LOC,X,0 !MEGTAMASZTAS

D,ALL,UZ,,,0

ALLSEL,ALL,ALL

NSEL,S,LOC,X,0

NSEL,R,LOC,Y,0 !SZELSARU

D,ALL,UZ,,,0,UY

ALLSEL,ALL,ALL

NSEL,S,LOC,X,144

NSEL,R,LOC,Z,-11.285

NSEL,R,LOC,Y,-23.463,23.463 !TELJES MEGTAMASZTAS PILON ALJ

D,ALL,ALL,,,0

ALLSEL,ALL,ALL

NSEL,S,LOC,X,444

NSEL,R,LOC,Z,-11.285

NSEL,R,LOC,Y,-23.463,23.463 !TELJES MEGTAMASZTAS PILON ALJ

D,ALL,ALL,,,0

ALLSEL,ALL,ALL

NSEL,S,LOC,Y,15

NSEL,A,LOC,Y,-15

NSEL,R,LOC,X,588 !MEGTAMASZTAS

D,ALL,UZ,,,0

ALLSEL,ALL,ALL

NSEL,S,LOC,X,588

NSEL,R,LOC,Y,0 !SZELSARU

D,ALL,UZ,,,0,UY

ALLSEL,ALL,ALL

NSEL,S,,,6168,6173,5 !LEKOTES

F,ALL,FZ,-4000*1000

ALLSEL,ALL,ALL

NSEL,S,,,6188,6213,25 !LEKOTES

F,ALL,FZ,-4000*1000

!TERHEK

!///////////////////////////

ACEL,,,9.81 !GRAVITACIO

!KABEL FESZITES

!///////////////////////////

*DO,I,1,2,1

ESEL,S,TYPE,,3

INISTATE,DELETE

ESEL,S,,,3733+2*I,3734+2*I,1,1 !KABEL ELEMEK

INISTATE,SET,CSYS,-2 !LOKALIS KOORDINATRENDSZER

INISTATE,SET,DTYP,STRE !FESZULTSEG

INISTATE,DEFINE,,,,,1000000000 !FESZITESI ERTEK

LSWRITE,I

*ENDDO

FINISH

!MEGOLDAS

!///////////////////////////

/SOLU

ALLSEL

ANTYPE,0 !ANALIZIS FAJTA

PSTRESS,ON

OUTRES,ALL,ALL !FESZITES BEAKCSOLASA

LSSOLVE,1,2,1

FINISH

Ansys solves the problem, but got an error wich says:

*** ERROR *** CP = 626.422 TIME= 17:49:37

LSSOLVE looping is stopped because of a solution error.

In post procesing I have some sort of result, but it has only one load step, and gives a rigidy body displacement (I added the picture as a file).

Do you have any ide what did I mess up? If I prsetess only one pair of cable, and ask Ansys for solution, it perfectly works withou any errors.

My other problem is about elemnt table results. I would like to write out the element table result into a text file, but I don't have any idea how could I extract the results with scripts.

Thank you in advice for your help,

Rafael

I mean simply a structural analysis of different bridges.

For modeling bridge deck slab on ANSYS APDL, why is shell element preferred over solid element?

I read somewhere that the mesh of shell elements is more efficient than solid elements. Why is that?

For the bridge shown below, the web is connected to both flanges, and the slab is connected to the parapet by meshing and merging the nodes, but what is the name of this connection?

is it semi-rigid? rigid? pinned? fixed?

Can i say the parapet-slab connection is rigid?

In general, what is the connection between elements on ANSYS when we merge them together?

I modeled a bridge on ANSYS APDL and added cross bracings / diaphragms as shown below. The diaphragms are not straight along the x or y or z direction, they are inclides BEAM188 elements.

how can I get the axial stress for inclined Beam188 elements?

I want to automate all by bridge modelling not directly using the program interface rather using a scripting language like matlab,vba,.net etc.

Sap2000 provides OAPI but I could not find options for substructure design in the software using OAPI and CSI bridge seem to not giving any OAPI.

So I want to know which is the best FEM software available which gives scripting or api interface to model my bridge(both superstructure and substructure)

Which feature of Fluent 14 is able to simulate pier scouring?

Dear colleagues

I have faced to a problem in extracting contact force of rail-wheel in transition zone which have been modeled in ABAQUS. there are many kind of contacts there, but I'm not sure which one suites my problem in transition zones. I was wondering if you can help me to find out this subject.

by the way I enabled CF(contact force) of Field Output but there is no CF in my .odb files which are my results.

many thanks for your kind consideration.

best regards,

Saeed Sotoudeh

The reinforced concrete plane frame with lumped plasticity approach is developed in OpenSees using Joint2D element for panel zone and elastic elements for beam and columns. When I model four springs with Modified Ibarra-Medina-Krawinkler Deterioration Model with Bilinear Hysteretic Response (Bilin Material) for four springs and elastic spring for shear spring at the center of the beam-column joint, I got unexpected results using this bilinear model. It means that I am using inappropriate material model or something is missing to include nonlinearities in beam column elements.

Please suggest me which material model should be used for four spring considered in Joint2D element (Arash Altoontash, 2004). In addition, advice me how to model shear panel in RC beam column joint by any other options to get reasonable results.

BRIDGE ENGINEER

M.E/TECH IN STRUCTURAL ENGINEERING

ABOVE 7 YEARS OF EXPERIENCE

I am performing non-linear analysis on a bridge deck modeled as a layered shell element. The bridge deck is supported by four concrete girders which are modeled using section designer in SAP2000.

I am applying the load in steps in order to measure the deflection on in the model for the loads.

Hello,

presently we are joining big (example 5 meter X 5 meter) laminates using bolts or some other aiding material etc etc. My question is how to join these big panels with zero radius. and if it is there what is the price?? Thank you in advance. Material is glass reinforced polyester laminates.

I'm working on the RCC bracing concept to reduce the displacement. using push over analysis through Etabs V13. Do the bracing required to be assigned with hinge, if yes which book could I refer?

What are the methods for internal damage detection of structures?

Hello everyone!

I just enrolled for a phd and need to determine what my research and thesis will be about. From the start I considered concrete bridges for research. There is an incredible opportunity in my vicinity where two concrete girder slab bridges will be built. Both bridges have two roughly 25m spans, but one bridge is an integral reinforced concrete construction, while the other one is a prestressed concrete construction with bearings on the abutments. This seems like a perfect opportunity to set up a thesis, put some monitoring instruments on the bridges and in a year or two draw a conclusion and see differences in reinforced concrete bridge and prestressed concrete bridge. Whatever the thesis is about the plan was to also do a numerical model of the bridges and see their behaviour using probably SOFiSTiK.

All of this is fairly overwhelming so I would like to ask all of you for help. I already looked up some dissertations but cannot decide what would be good to do here. I am open to all suggestions (creep, shrinkage, cracks, earthquake, etc.) with little guidance.

Thank you all very much for your time!

I am trying to model the foundation of a bridge that has damage to the junction of the column foundation with the piles and loss of cross section and, I would like to know how it could take into account the damage to the piles in the mathematical model.

Any and all advice would be great

Thanks!!!

What might be the future of cable-stayed bridges in terms of need, choice, affordability and number !?

Could anybody share the details geometry and material properties of simple supported reinforced concrete bridge beam/girder based on following.

1. AASHTO, Eurocode or any others standard

2. Without prestressed strands, only reinforcement concrete (with reinforcement details)

3. geometry details based on different span

4. T-Beam/Girder or just simple rectangular beam

I would like to know if "2008 NYC DOT seismic design guidelines for bridges considering local site conditions" is implemented in practice or not. If anyone has some information regarding this it will be really helpful.

Hi everyone,

I am developing a shell element model for a concrete bridge. I am currently at a stage of assigning the traffic lane UDL.

As you can see in Figure 1, the traffic lanes are unfortunately at a angle (not 90 degrees) with respect to the horizontal direction, in other words, are not in parallel with the bridge span direction.

My model is shown in Figure 2. It is already been meshed.

Can someone please give me some hints on selecting the elements that are under the traffic lanes; hence I can apply required UDL on them?

if the lanes had been perpendicular to the horizontal, I would have used NSEL,S, LOC,Z,(elevation of bridge deck) and NEL,R,LOC,Y, (coordinate of the left and right boundary of the lane), to select the elements. However, it's been difficult when the angle is not 90.

Thanks.

Hello all,

I would like to ask about how to model rigid and flexible joints "connections" in SAP 2000?

Thank you in advance

I am looking for any resources related to this field. It might include things like 1] aesthetic treatments to hard surfaces (soffit, paved traffic islands, bridge retaining walls, etc), 2] Lighting, 3] Signage, 4] Pedestrian and Vehicular Safety, 5] Greening of the interchange, 6] etc.

Bridge is of a 175m span, post-stressed cables, Software preferably in Sofistik AG, could be in Autodesk Robot 2012.

For Curve Segment Cable Stayed bridge. What is the design criteria for max. twisting moment to find manually as per IRC or lrfd or any other standard. or a any equation related to find twisting moment.

I have to calculate the optimal thickness of well steining for a well foundaton having external diameter 11.6 m and depth 30 m.

IRC 78-2014 gives the formula h =kd√l .Using this formula, thickness will be about 1.9 m. It has been proposed to use Jack down method of well sinking.

Clause 708.2.3.5 of IRC:78-2014 allows to adjust the steining thickness according to design and construction requirement if specialised method of sinking such as jack down method are adopted.

Some case studies to mention here are:

Signature bridge, wazirabad in north delhi having 0.8m steining thickness for a well diameter 8m and depth 35-39 m (jack-down method used here)

Pretensioned sutlej bridge in Punjab having steining thickness 1.05m tapered to 0.75m for well having diameter 6m and depth 32m. (jack down method not used here)

According to the book "Soil Mechanics and Foundation" by B.C. Punmia page 789, steining thickness is given by

t =D/2{1-√1-4r/ρD} ; t is thickness, D is Dia of well, r is unit skin friction, ρ is unit weight of concrete for steining.

As per this equation for a constant skin friction, steining thickness should decrease with increase in diameter of well.

According to the book "Structural detailing in Concrete" by M. Y. H. Bangash, thickness of steining is given by

t=k(0.01H+0.1D) ; t is thickness, k is sub soil constant, D = external dia of wall , H is depth of well.

Using any of the formula, the thickness of steining wont come close to the thickness provided in the case studies i mentioned above.

By using Jack-down method of well sinking, thickness will be reduced, but how to calculate the optimum thickness of well steining in case of jack-down method?

I notice that the steining thickness equation provided in IRC 78-2014 gives the thickness which increases cost of the project.

Your esteemed comments and experiences are highly welcomed and appreciated on this topic.

Hello everyone

I am simulating the suspension bridge given on the pictures by ANSYS workbench.

However, I just add the earth gravity force(self weight ) on the structure but it has exceeded the allowable deflection in vertical direction.

So I was wondering whether the anchorages of bridge use the pull force to cancel the self weight of bridge?

I will very appreciate any replies.

I modeled a concrete bridge by sap2000 and developed nonlinear time history analyses to obtain maximum deck displacement in longitudinal and transversal directions. Could anyone have an idea about it?

how i can find the results of the " flieden bridge piled-raft foundation " paper ,if it possible please ?

Hello,

I need to calculate the area which is less than 0.5Pa.

In Wall shear stress contour, I would like to calculate the area except for the red colored-legion.

Please let me know how to do it.

I have the data such as x,y,z, WSS and so on in the excel.

Thank you in advance.

I'm new in Bridge Engineering

How can I modelling a steel box girder (deck) using Midas Civil engineering software?

There has been historical mention of the construction of bridges in ancient societies even in B.C. times, but I have yet to find any documentation on any specific bridges from this time period. I am interested in learning more about these ancient bridges, but as most of these bridges are not still in existence I'll have to rely on documentation on the existence of these structures, or archaeological evidence proving they existed. How would I go about finding this information?

Are there mitigation measures put in place?

for experimental analysis of scour depth at particular site, How can I proceed if I am starter in the civil engg. field ? What experiments are mandatory for this?

I want to apply the statistical parameters (bias ,and COV) on three and four lane bridges but the available data can be used for one and two lanes.

I am looking for references regarding piers which are monolithically connected to deck at concrete bridges with prestressed-precast beams.

For the analysis design and construction of a suspension bridge.

I want to automate my bridge constructions for which I am using sap2000 OAPI.But I could not find any OAPI for the csibridge.

Does any OAPI exist for csibridge or it is provided for only for the sap2000??

sap2000 OAPI does not contains the substructure modules so please tell me how do I automate my model if it has substructures and other options (like bearing,abutments)which can be done in csibridge.

I wonder if someone can send me reports or address of links that I can find relating to severe damages of concrete bridges in Iran based on past earthquakes.

my research about an experimental test on horizontally curved steel I-girder bridges, so I need the AASHTO LRFD formula 1998 for comparesion purpose

For determining the acceleration parameter Ss and S1 the site class is compulsory to select first.

As per ASCE 7-10 which site class (form A-F) can be taken as it can be similar with the medium soil site given Indian Standard IS1893-2002?

Both method consider that loading is at crown of masonry arch bridge. For a train having multiple axles at boogie, there is a standard loading as mentioned in brackets but that is a maximum axle load of any axle for that locomotive. If I get a value of Provisional Axle Load (PAL) by MEXE, how do i compare that with railway standards?

Hi everyone,

We know that AASHTO LRFD bridge design specification for stud design is based on the push-out tests performed by Slutter and Fisher. They proposed an equation showing the relation between stress range amplitude and number of cycles to failure for a shear stud as follows,

Δτ = 1020 n

^{−0.186 }_{where Δτ = stress amplitude and n = number of cycles}

Could anybody please tell me whether this relationship is accepted by AASHTO LRFD to calculate number of cycles to failure when stress amplitude is known. If not, then how it can be determined.

Physical modelling requires to assume some scale factor according to the available space for the model study.But it is also fact that low scale give good results(CHETN XIII-3,Briggs 2013, USACE). Why is it so? How is it related to scale factor?

I am trying to calculate the fatigue life of a concrete structure under cyclic loading.

The methodology for completion of fatigue assessment of concrete bridges is not that clear.

for steel structures, the procedure is vague. The code has been adopted based on Euro-code 3, but it seems that there is still a need of the old version of AS5100.6 in order to complete the assessment.

The effect of DLA is doubled in formula ( once has been applied in AS51000.2 as f* and again in AS5100.6). Considering this change and value for Lambda(t) , the fatigue life significantly reduce resulting in an adequate remaining life for bridges.

I would appreciate if you share your experience with the new code and provide procedure/examples that you have used in your assessment.

Regards,

Mehdi

Dear Structural/Bridge Engineers!

As per AASHTO LRFD, we can ignore earthquake loads while designing of single span bridges. My question is if the span is long so should we consider the seismic loads or not?

Thanks

I am tryng to assess whethere the deflection under traffic load for a bridge slab is acceptable. Can anyone help with this ?

A motorway bridge has collapsed near the Italian city of Genoa, sending vehicles plummeting some 100m (328ft) to the ground and killing at least 11 people, local media report.

I have designed a 60 meter (196.85 feet) simply supported cast in place (directly casting on bearing pad) post-tensioned prestressed concrete I girder due to the requirement for horizontal clearance of the respective channel following AASHTO LRFD Bridge Design Specification.

Do I need to consider any special check besides traditional design checking of post-tensioned prestressed concrete I girder?

Please provide the values or equations for (corresponding references if any available)

- Crushing strain of confined core concrete
- Spalling strain of Unconfined cover concrete

Thank you

On pages 148-151 (RG numbers 171-174) of my book,

**Geometry-Do**, I prove the skew angle theorem, some other related theorems and I solve several triangle construction problems.Are there any structural engineers on Research Gate who have worked with skew bridges? Can you suggest any theorems or triangle constructions that would be useful in the construction of bridges?

I want to make my geometry book as useful as possible to engineering students and I will very much appreciate any suggestions.

Hi all,

I am doing analytical study on behavior of chevron (eccentric) bracing with pall friction damper in RC structures using Etabs. I am looking details for mass, size and stiffness of pall friction damper connected between braces and roof.

I saw that in many design details of bridges.

I am looking for the governing equations of infinite plate hole problem. For reference, i have added the picture. I have found the exact solution of the infinite plate hole problem in terms of stress and displacement however, i want to know the main governing equations in terms of differential equation.

I will appreciate this..

Thanks

Regards

Zulfiqar Ali

Indian standard code of practice for Prestressed Concrete Design I

*for varying l/d ratio and reinforcement index. However, the***S 1343 1980 had table number 12 for the design of Unbonded post tensioned concrete***. Nothing is mentioned explicitly why it has been removed?***same has been removed in the recent revision of IS 1343-2012**Does that mean Indian standards does not allow Unbonded PSC design in INDIA?

Yesterday in the field we had some trouble with the bleeding in our concrete, the bleeding was adjudicated to the admixture (we use sikament 450 at .08% per weight of cement), here is some data:

· We were constructing a part of a bridge column of 200 cubic meters, the F´c was targeted at 350 kg/cm^2, the concrete slum was aimed at 18 +3 cm.

· Mix design

400 kg Cement

957 kg Gravel (3/4”) M.F. 6.7

783 kg River Sand M.F. 2.7

210 lt Water

3.2 Lt Sikament 450 (low range water reducer)

The aggregates satisfy the regulations and codes, but due to the severity of the bleeding, i want to find out:

1) The probable source of the bleeding (I think it is the excessive use of dispersion admixture)

2) How can I stablish the severity of the bleeding?

3) Is the color or the bleeding water normal?

I want to find the torsional and bending stiffness for a box girder. Is there any particular formulas or software which I can use do i need to find for individual member and then add them together?

hello again guys,months ago i've asked you for a software that was able to solve dams modeling and your answers were awesome, now i have a new question for you, i've been looking for some information about Tension and Compression Models on bridges, im reading the bridge design practice and i dont have a clearly idea about this topic, can you help with this please? im looking for more especific information about this, or if you can, give some type of bridges that are on tension and compression model, thanks for the answers, regards.

Hi everyone

I am studying the suspension bridge.

But I can not find any information which is vertical and horizontal allowable / permissible deflections for suspension bridge.

who can tell me?

It is best to provide the links for me.

Thank you very much!!!

I need to do scaled down model studies of an existing river bridge. Froude number dynamic similarity would be maintained.I need to know the criteria for scaling down the size and properties of the river bed material to be used in the model.

Dear all,

Most of the research papers are showing academic applications of the various truss structure.

I would be glad if you please share some real world examples of various truss structures (as spatially for topology optimization). Please share related webs, images, pics etc.

Please refer trusses designed in the following papers

Thanks for your support

bridge girder is placed on three columns placed next to each other . which method we have to opt to get optimum results to design ?

In SAP 2000 in a analysis time history is the behavior of a link element that simulates the behavior of a force displacement of a hinge assumed when using the direct integration method?

Isolation Time Period T= 2 sec

Bridge is horizontally curved 3 spans box girder 88 m length

8 isolators - 2 under each pier and 2 at each abutment

I'm doing link slab design for prestressed concrete bridge, may i know is there any formula in accordance to BS code which determine the end rotation of link slab due to creep and shrinkage?