# Questions tagged [structural-analysis]

Structural analysis is the determination of the effects of loads on physical structures and their components. Structures subject to this type of analysis include all that must withstand loads, such as buildings, bridges, vehicles, furniture, soil strata, prostheses and biological tissue.

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### How can we derived the equivalent Lumped Mass Model for irregular building and how to calculate the errors?

Intuitively, building can be represented as a lumped mass model ( the taller the merrier!): Assuming a building is a lumped mass cantilever column also makes the global stability checks easier ...
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### How quadrilateral elements represented in most FEA solvers for structural mechanics problems?

How quadrilateral elements represented in most FEA solvers for structural mechanics problems? I know that Nastran-95 represent quadrilaterals for membrane and bending elements as a set of triangles: ...
284 views

### How to integrate ∫vᵢ(uᵢ² + vᵢ²)dA in calculating monosymmetry index of an angle?

I saw this question asking about calculating monosymmetry index of an unequal angle. What I need is a formula to calculate $\int v_i{(u_i}^2 + {v_i}^2)\text{d}A$, given the depth $d$, breadth $b$ and ...
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### How to obtain relative movement and rotation of bridge bearings?

In structural analysis of a bridge using whatever software, such as MIDAS or SAP 2000, it is easy to obtain the deformation of individual nodes. However, for bearings, what we want is the relative ...
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### Does hitting an obstacle hard enough to break it actually reduce self harm?

Lets say that Car-A hits barrier that is fixed to immovable posts on either side of the road. The car's momentum is such that the barrier absorbs the impact and the car comes to a near instantaneous ...
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### Bar released from upright position rotates about a lower hinge before being caught by a steel cable, how to calculate the tension on the cable?

I wish to check the safety factor of a steel cable that I've designed to catch a heavy bar that rotates freely due to the gravitational force acting on it. From the upright position, I'm assuming that ...
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### Hencky nets/slip-line fields on the the interior of a closed domain

This is a crossed post. The equations for Hencky nets are usually solved in the exterior of some domain; typical examples are the upper half plane or the exterior of a circle. I would like to know ...
369 views

### Bending moment calculation

Considering all the variables are the same, how to rank these connections from highest to lowest bending moment?
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### Help sizing of lug attachment flange/plate?

Apologies for the crude drawing attached, but here goes. Given Fx, Fy, and Fz loads applied at the lug hole, I've distributed the loading into each of the 6 fasteners to size them. I've also sized the ...
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### In a nonlinear static two-step subcase, why does the load step decrease after the first step?

I am using MSC Nastran for nonlinear static analysis (sol 400). Step 1 contains a small perturbation load laterally on a thin-walled cylinder. Step 2 contains a very large compressive load. ...
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### How to compare two acceleration sensors side-by-side?

I have a single axis analog capacitive acceleration sensor (from PCB Piezotronics) which is very reliable but expensive. Now I need more axis, unfortunately can not afford buying anymore. So I have ...
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### Analysis method for two-way slab floor with central column

What method would be appropriate to analyze this concrete structure? A two-way rectangular concrete slab with walls and central column. I would like to understand how to model it with either yield ...
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### How to join two beams rigidly?

Hi I am making a beam model using Abaqus. There are two beams created. I wanted to join two beams rigidly in the connection to transfer moments between beams. However, I do not know what connector or ...
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### Affect of Cast in Pipes in a 1m thick Raft Slab on shear

I am designing a 1m thick raft slab and the drainage guys have thrown in 100mm diameter cast in pipes all over the raft. See Attached images 1 & 2. Wondering how this will affect the shear in the ...
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### how to release specific degree of freedom in ANSYS Workbench?

I'm designing a truss which has 9 elements in ANSYS Workbench. since it is a truss, all of the elements are truss elements and can not tolerate momentum. I used <...
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### FBD of folding table leg

I've drawn an FBD of one leg of the table the picture. I've a feeling I'm missing something. Am I?
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### Structure's equlibrium state

The state problem of a structure at equilibrium is generally expressed as: $K(x) ~u = F(x)$ where $K$ is the stiffness matrix, $u$ is the displacement vector, $F$ is the force vector, and $x$ is the ...
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### Pumping water from under concrete slab basement

I have this situation, and wanted someone's opinion. Info: Concrete foundation basement, slab floor Weeping tiles and a sump pump is present / operational The house is near a pond. Grading is alright,...
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### Finite Element Method for Spherical Objects

I am familiar with the procedure of the FEM for simple planar objects like truss and etc. but my question would be whether it would be possible to use this method to calculate the stiffness or ...
1 vote
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### What material performs best in this situation?

Take a long, thin rod, say .25 mm in diameter and 200 mm in length. Filling these fixed dimensions, what kinds of materials could the rod be made of such that it minimizes how much the rod bends under ...
1 vote
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### How to determine the resistance provided by cement mortar?

I am attaching a steel rail and post guardrail to the coping of an existing parapet. The actions produced by the guardrail on the coping incur at point A as shown below. However, how do I find out if ...
1 vote
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### Why is there a negative sign in case of moments caused by longitudinal stresses?

I came across the following relations in the plate theory. I, however, don’t understand the reason for the negative signs in Mx and My. There is, however, no negative sign in Mxy. I am guessing, this ...
1 vote
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### Do we allow mass and moment of the footing itself, when calculating ground support and eccentricity of a footing?

Suppose we are designing a footing for the wall of a building. There are two checks that are crucial. Ground support: suppose the ground is assessed as being suitable to load up to 80 kN/m2. Then a ...
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### Will my brick veneer wall sustain the additional load of natural thin veneer stone, wire mesh, and plaster placed on top?

I have a (full, not thin) brick veneer wall on the front of my house. It is tied into the plywood (covered with paper) via wall ties and screws. I am wondering if I can apply plaster and wire mesh as ...
1 vote
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### Tension cable underneath rafter tie?

I just bought a new property with a large garage and I'm curious about the roof structure. The roof structure is supported entirely on the front/rear walls using rafter and collar ties. The rear wall ...
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### How to export 'simplified' geometry from Simulation workspace in Fusion 360 to ANSYS Mechanical?

I would like to export the defeatured version of my design to ANSYS. I tried adopting the following methods but they weren't working out. (https://forums.autodesk.com/t5/fusion-360-design-validate/...
1 vote
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### Using seismic base isolators in light, flexible buildings

Using seismic base isolators dissipate a great deal of energy that would enter to a structure, but at the same time they increase the natural period of vibration of the structure. Now, if we had a ...
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### Distribution of Forces into 3D Bolt Group

I'm trying to create an Excel spreadsheet that takes a 3D bolt group with x y and z coordinates, applied loading, and determines the distribution of forces into each bolt based on weighting by the ...
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### Should I use ST or LT values for extruded rod?

In MMPDS for AA7075-73511 (extruded rod) the Table 3.7.10.0(g3) show both ST and LT values for transverse directions. For a rod with circular cross section there is really no Short and Long transverse ...
1 vote
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### Modal Response Spectrum analysis

Is "Modal Response Spectrum Analysis" the same as response spectrum analysis? How about modal superposition analysis? This is the same or different? Or all are same?
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### In Nastran, how to ignore fatal error due to failed convergence and move on to next subcase?

At the moment the whole analysis stops when 1 subcase fails to converge. How can I keep the analysis going such that all subcases are are run, even if they all might produce an error? I'm pretty sure ...
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### Finding reactions of a continuous beam

is it possible to find all the support reactions of this continuous beam using fourth order equation without using principle of superposition?
1 vote
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### Analysis Of Planar Frame Using Hardy Cross Method (Moment Distribution) With Sway

The image shown below is a sketch of the structure/frame that I am attempting to analyse using the Hardy Cross (Moment Distribution) Method. I need to find the bending moments, axial forces and shear ...
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### Constrained optimization using Lagrangian

I'm trying to optimize the weight of a truss with the constraint that the trusses don't face more stress than the material resistance. Here is a sketch of my truss: I have a Python function that ...
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### Etabs Semi Rigid Diaphragms

In Etabs, if I model a building with semi-rigid diaphragms assigned to the floors, the floors will now transfer gravity loads when default meshing is assigned (as compared to rigid diaphragms ...
1 vote
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### How to state the PSD value (random vibration)

In random vibration analysis, the load is given as a PSD (power spectral density). The values are often $G^2/Hz$, but I have an example where the PSD is a pressure $Pa^2/Hz$. The value is written as \$(...
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### Honeycomb structures vs shear stress

Honeycomb structures are made of top and bottom shells and honeycomb geometry at core. In terms of bending load, maximun normal strains take place on top and bottom hence, sheet parts can support them ...
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### STEEL CONNECTIONS

Hi, so, would you consider the connection detailed here as fixed or pinned during your structural analysis?
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### Most efficient way for finding the rotation angles after moment distribution (Cross method)?

First of all, I have taken a look at the Grinter's method, which is similar to Cross, but balancing angles instead of moments. My question assumes that we are using the Cross method, and not the ...
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### What does 'Analysis Model Value' in NASTRAN optimization mean?

I am new to MSC NASTRAN and PATRAN. I am running a simulation on composite laminate optimization. While creating the design variables for the study, I noticed that there is a parameter called '...
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### Calculating the Structural Forces Required to Support a Robot on an Overhanging Beam

this is my first time posting on here and I have a question regarding the structural properties a beam will need in order to fulfill some requirements we have for our robotics team. The scenario is as ...
1 vote
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### Beam element stiffness matrix for variable area cross section with mass and shear center not coinciding

I would like to find the full (12 by 12) Timoshenko beam element stiffness matrix for a variable cross section with mass center axis and elastic center does not coincide. I have the full stiffness ...
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### Check of a nominaly pinned steel joint

I am interested how to check a nominally pined joint. Especially how to check its rotational capacity and whether i can define it as nominally pinned in structural fem model. I understand that there ...
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### Maximum slope of the road for a car pulling a trailer

I have a five meter long, 2.40 meter wide, 200 kg portable catamaran I've built at home. To transport, I bought a semi-finished trailer, just the running chassis; and built the upper structure, namely ...
1 vote
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### How can I use the bending stiffness of corrugated cardboard to determine maximum stacking heights of pallets loaded with glass bottles?

I am doing a project at the moment which involves improving the packaging operation at work. Right now I am looking at ways to improve packaging selection based on engineering principles, rather than ...
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### What are the general consideration for tendon profile in a post tension slab?

How the tendon profile is calculated for banded-distributed disposition? In the following figure why is the tendons profile one in the top fiber and the second in the bottom fiber? If the location is ...
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### What is the minimum diameter for vertical bars in a column according to ACI?

What is the minimum for vertical bars in a column according to ACI and I am looking for a particular condition where diameter must be greater than 0.625 in. (when using S-concrete for column design it ...
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### Is it possible that a considerably thicker portion of slab would decrease the moment capacity of a raft slab

If I Design this slab as a flat 1500mm thick slab throughout ignoring the step will the design be conservative. I'm worried the extra stiffness created by the step, will attract the moment into the ...
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### How would I model a load bearing brick wall supported on a beam in FEM

I have a continuous beam supported on columns. I need the brickwork above to act as load bearing wall for the next floor above. How would I model this in a FEM suite like SUMO (Prokon) ? In SUMO I ...
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