Questions tagged [structures]

Questions relating to or the engineering application of a device that must withstand a loading via deflection, stresses, resistance to buckling, or natural frequencies.

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1answer
347 views

How do I create a graph of the phase angle and response of a harmonic excitation in Matlab?

In my course of dynamics of structures, I am struggling with some basic principles. As a practice, I am plotting (or attempting to plot) the curves that are shown in the course book, with the help of ...
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1answer
606 views

Which is the best way to construct a trapeziun dome with a 76' diameter

When building a trapezium dome, is it better to construct the dome row by row or by first making a vertical arch? Is some form of bracing required?
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546 views

How different is using styrofoam rather than empty cans when pouring concrete?

In the recent 6.4 earthquake that hit Taiwan, it was seen in a newswire photograph of rubble that metal cans were embedded in the concrete. The quote from an official regarding this practice: For ...
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0answers
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best way to reinforce existing structural header?

House remodeling. I need to enlarge (from 7 to 10-12 ft) and shift (about 5ft sideways) an existing header where one passes between rooms. On one side, the header has 2x8 ceiling joists nailed to ...
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2answers
1k views

How is biaxial bending considered for reinforced masonry design?

I am faced with a problem where I have to design a reinforced masonry beam for biaxial bending. The governing code is ACI 530-11. I cannot find a provision in this Code for biaxial bending. The only ...
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2answers
4k views

Best angle and length for a diagonal wood support for a pull-up bar

I want to construct a freestanding pull-up bar like the one described here. But I was wondering what would be the best angle for a diagonal support considering that the things I care are: That it ...
3
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1answer
278 views

Calculating stresses of section with varying depth

I'm trying to solve the question attached below (please note the handwritten values are ones that I calculated/not part of question) I am assuming that to find the load $q$ I need to get the bending ...
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1answer
4k views

Finding Neutral Axis of a simple shape undergoing axial load

I know that the neutral axis occurs where the sum of stresses (bending + axial) is equal to 0. I have found the stresses and drawn a diagram to represent forces. How do I determine the neutral axis?
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1answer
1k views

How to estimate the required thickness of a transfer floor

I am examining a high rise building project of 30 floors with a podium underneath and 2 basements. The structure in the tower and the podium varies between flat slabs, steel structure for wide spans, ...
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2answers
8k views

How to calculate deflection of a simple beam with a load in the center?

Given this type of arrangement: - image by Hermanoere Where the beam is of rectangular cross-section. I am specifically thinking of a wooden beam where I can look up some material characteristics (...
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1answer
1k views

Loaded Truss problem

Hi, I'm having some problems with this truss question that I have in my homework. So far this is my solutions. I worked out my solutions to the reaction forces but don't know if they're correct. The ...
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5answers
9k views

Is hydrostatic pressure a dead load or a live load?

I have a structural analysis question. I want to know if the hydrostatic pressure in a water tank is a live load or a dead load and why?
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1answer
1k views

Calculating automotive suspension wishbone loads by considering the structure as a 3D Truss

I am trying to calculate the loads in the suspension components of a typical car double wishbone setup. I have found a thread on the www.fsae.com forum, which seems to be exactly the kind of thing I ...
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2answers
417 views

First glance: structural integrity of this roof

There's a rooftop we recently discovered with a great view, and it's easily accessible for us. Obviously we'd like to go up there a bit more, particularly in summer with a couple of fold up chairs or ...
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3answers
406 views

How much strength does adding a T piece add?

If I have a flat span of steel material, 3.0m x 150mm wide and 5mm thick, and apply an increasing downward force to the middle, at some point it will fail. But if the profile of that piece of steel ...
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1answer
706 views

FEM 3D truss analyzer produces forces that do not sum to zero at joints

I am writing some code for the analysis of 3D truss structures. The program is a typical implementation of the direct stiffness method for truss elements. While testing it and comparing results to ...
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1answer
481 views

Dynamics of structures: combined plane stress and plane strain conditions

Problem statement For an engineering project in school, we are checking the stability in the longitudinal direction of an apartment building, taking into account the dynamic effect of earthquakes. ...
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1answer
16k views

What angle - for a strut - provides the greatest vertical strength/support for a cantilever?

I want to affix a cantilever to wall. I will support the other end of the cantilever with a strut made of wood, that attaches to some point on the wall below the cantilever, as shown in this sketch (...
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3answers
2k views

Does the length of a beam change upon deflection?

I have made a Python program in which I have computed the deflection of a beam. I am plotting the deflected beam and am now asked to show the length of the beam. If the beam is not deflected, it is ...
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2answers
3k views

Beam with constant load distribution on three supports - force distribution to supports

I have following example (the question is at the bottom): The load distribution $q$ is constant. I add condition of zero bend in center of the beam, $w_B = 0$, and the assumption $F_{RA} = F_{RC}$. ...
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3answers
1k views

Is a permanent platform that is hanging and moving a dead load or a live load?

If a permanent room or platform is suspended from a larger structure (say, on a cable that is attached to a hook on a track in a ceiling) and designed to be in constant but not necessarily repetitive ...
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3answers
483 views

Is a distributed load in two parts equal to a full distributed load?

I have a structure like such: Due to my lack of knowledge of ANSYS, I have made the singular distributed loading (GI) represented as two distributed loadings (GH and HI). Would this be an accurate ...
13
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1answer
976 views

Why does prestressing in trees make them stronger?

In "Structures: or Why Things Don't Fall Down" James Gordon talks about trees being prestressed with the outside in tension and the inside in compression. Why does it make a tree stronger to have it ...
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1answer
2k views

Logic behind location of shear centre

When we apply a vertical shear force Sy and the structure is symmetric about x axis, then why is it logical to have the position of shear center at the location of intersection of line of action of ...
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0answers
291 views

How to account for pistons inside a free body diagram? [closed]

If you have taken basic statics classes you'll remember the free body diagrams used to calculate the forces inside a mechanical system; such as a beam structure consisting of pivots, rollers, fulcrums ...
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1answer
1k views

How high can you stack mobile homes?

In Ernest Cline's novel Ready Player One, the main character lives in the "stacks" - a dystopian vision of what a trailer park may look like in the future. The "stacks" are primarily composed of ...
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1answer
264 views

Is a building story actually 10ft (3m)?

In common US usage, the heights of tall things are sometimes converted to a "number of stories". The thinking is that people can better compare heights to similar tall buildings that they might have ...
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1answer
447 views

Is there a theoretical bound to how tall a structure can be built?

Assuming that there are no constraints on cost, land to develop, or supply of materials, is there a theoretical limit on how tall a structure can be built? What are the main physical constraints that ...
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3answers
686 views

What concerns would I need to consider for building a swimming pool of gold coins?

If I wanted to build a gold coins swimming pool [as in DuckTales], what engineering (not security) concerns would I need to address to make such a pool feasible? For example, since gold is much ...
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1answer
2k views

Why build a cell lattice tower with square cross-section instead of triangular cross-section?

First, a neat image from Wikipedia Here the cell tower has three vertical (or maybe slightly inclined to the inside) thicker pipes which are located at angles of a triangle and those three thicker ...
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2answers
1k views

What is the best insulation wall for a house? ACC wall, Cavity wall, etc

Normally, people use Autoclaved Aerated Concrete (AAC) to build a concrete house because ACC is a good thermal insulation brick that easy to buy and not expensive ...
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2answers
2k views

What is the practical limit on the number of storeys in residential buildings built with monolithic reinforced concrete?

I have recently bought a flat in a 25-storey building. I wonder what is the practical limit for the number of storeys in a mass-produced residential buildings built from monolithic reinforced concrete?...
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1answer
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Why are hyperboloid towers not popular anymore?

Hyperboloid towers were very popular in the end of 19th and the first half of 20th centuries - water towers, powerline anchor towers, sometimes tall radio towers were built using this design. The ...
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1answer
364 views

Additional jacking force to overcome stiction/dry friction

It is common to lift bridges to replace bearings, etc. In an ideal world the lifting capacity required of the jacks would be the self-weight of the bridge divided by the number of jacks (+ allowances ...
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5answers
366 views

How can we prevent/detect hydrogen embrittlement?

There has recently been a series of high profile bolt failures on 'The Cheesegrater' in London, which have been attributed to hydrogen embrittlement. What can engineers do to ensure that hydrogen ...
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2answers
1k views

Why are three way bridges rare?

It's true that most bridges are "two directional." But three way bridges are pretty rare, globally. I can understand why there wouldn't be many for rivers, but if bridges are designed based on the ...
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3answers
2k views

What kind of protection should I give structural steel in a natatorium (swiming pool) environment?

What would be the best type of steel to specify? Would a heavy galvanization suffice? Are there specialty paints/coatings available for this particular application? If so, how long do they last?

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