Structural Engineering Blog: SkyCiv S3D

7/6/2017

Working with S3D, Structural Analysis and Design Software In The Cloud, Anytime and Anywhere

SkyCiv is a structural engineering design and analysis software that runs on the cloud. SkyCiv files and programs can be accessible from a web browser anywhere and at anytime with any device. With SkyCiv’s organized file management system and cloud network, files can be navigated easily and be sent to other SkyCiv users for design coordination and progress reporting.

There is a diversified collection of programs within the SkyCiv Cloud Engineering Software, from calculators for beams, trusses, frames, and shafts. However, we will focus on Structural 3D (S3D), a 3D structural design and analysis software that can analyze structural members and plates.

Special Elements of SkyCiv:

Using preset material properties or customizing own materials

S3D already has default material properties installed within its software, from structural steel to aluminium, from concrete to high strength concrete, and from carbon fibre reinforced plastic to oakwood, etc. When choosing a material, default properties will be selected, such as modulus of elasticity, material density, Poisson’s ratio, yield strength, etc. On the other hand, material properties can also be customized or altered to suit project requirements.

Choice of modelling with the model or the database

In S3D, the structural model can be modelled by traditional methods of creating nodes in model space and connecting them with members manually or the model can be modelled by inputting your node location in a tabulated Cartesian coordinate system in the database. Therefore, S3D’s choice of input methods can cater to your modelling and organization style.

Realistic and Advanced Options for Members

You can specify the member’s type in S3D. It can be normal (supports tension and compression), compression-only, tension-only, or a cable. Members can also be offset from their centrelines with respect to the centrelines of their connecting members. This is since members are not usually fabricated or constructed at the centrelines in reality, since beams can be on top of columns or columns can be at the bottom of beams. Results with this function are the same as the results when both centrelines of the connecting members are collinear. This offset function is to present a real world representation of member locations.

Advanced Plate Analysis Options

S3D has the option for users to select whether their plates or slabs should be analyzed considering shear deformations or should be analyzed not considering shear deformations. There are also various mesh options, such as mesh geometry, meshing method and the level of mesh finess.

Section Builder

The Section Builder embedded in S3D provides an interface to build customized sections or to find the appropriate preset section in their database library. Here, you can find common geometries, such as hollow rectangular sections, circular sections, I-beams, angles, channels, box girder, etc. Once the appropriate section is selected, dimensions can be inputted or changed. The Section Builder includes different sections used in different international regions. Sections include American, Australian, British, Canadian, and European sections. You can also customize your own (or fabricate your own) structural member sections by building complex built-up sections or composite sections with different materials. Not only can you create your sections in model space, you can also import a CAD file (DXF file) of your section into the software for analysis.

A built in calculator is also provided to determine section properties that can be used for calculations and analysis. Parameters include:

Geometric properties such as area and centroid
Moment of inertia
Section modulus
Shear properties
Torsion properties

SkyCiv also went one step beyond and created an automated Hand Calculation function to show the derivation of these section properties.

Various Load Input Options

You can input area loads, distributed loads, moments, etc. In my test model, superimposed dead area loads (3 kPa for waterproofing and screeding at the roof) and live area loads (2 kPa for roof maintenance loads) were inputted via the software’s tabulated format. Using the Distributed Load function, a distributed load for 200mm thick and 150mm high roof parapet load and wind loads were inputted into the model. Distributed loads inputted do not have to be uniformed throughout. You can develop trapezoidal or triangular distributed loads. Using the Moment function, the moments due to the wind loads on the parapet are also inputted in the model.

For load combinations, you can customize your factor of safety for each load case or you can import load combinations based on code requirements from international standards and design codes.

Structural Analysis Solver

There are three methods of structural analysis that you can use.

Linear static method – This method analyzes linear structural behaviour, where stress is proportional to strain and no plastic deformation is induced.

Linear static and buckling method - This method considers Euler buckling and outputs maximum buckling loads of members and buckling load factors.

Non-linear static and P-delta analysis method – This iterative analysis method considers secondary moments created by the ends of laterally displaced structural members.

S3D considers usability and efficiency by having these three structural analysis options available. For more preliminary and faster results, you can choose linear analysis. However, if you want to consider nonlinearities, you can choose nonlinear analysis.

Presentation of Outputs

S3D outputs various results for your analysis:

Reactions (fx, fy, fz, mx, my, mz)
Shear and moment of members
Axial forces
Force diagrams
Torsional effects
Deflection and rotational displacement of members in x, y, and z direction
Bending stress, shear stress, combined stresses
Plate analysis

Presenting your results to your clients can be a breeze with S3D’s clear visual outputs. These visuals can show the deflected shape of the model under different directions. This shows the client where the locally stressed and deflected locations are in the structure, indicating structural areas of concern and where more strengthening works should be used.

Integrated Design Modules

SkyCiv also has integrated design modules such as AISC 360, which has a range of features for the design of steel structures. You can generate various results, such as your force capacity ratios and deflection analysis, and create a comprehensive data report of the results of your structural steel members.

SkyCiv

Try SkyCiv's S3D now!

This post is sponsored by SkyCiv.

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Structural Engineering Blog: Foundation Failures

5/24/2017

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The Different Types of Foundation Failures

Foundations provide the support and resistance of the loads of the structures above. They serve as structural systems that transfer loads to the soil below and that provide stability, including resistance to overturning, sliding, and uplift, for the overall structure. Due to the importance of their structural system to the overall structure, it is imperative that their structural integrity is maintained for the overall structure to function. However, in some cases, foundations can fail. We are now going to explore the different types of causes that can affect the failure of foundations, in order to prevent and remediate the failures.

Causes of failure

Source: http://www.msdpe.com/

Uneven loading

The uneven distribution of loading from the superstructure can induce uneven stresses at different locations of the foundation. This can cause differential settlement at locations where vertical structural elements, such as columns and walls, directly transfer the superstructure loads to the foundation. Differential settlement can eventually lead to cracks at the foundation.

Overloading

Overloading from the superstructure can also create foundation failure. Foundations can fail by cracking when the design moment and/or shear is above its moment and/or shear capacity. Failure can also occur when there are large concentrated or point loads, which can induce large punching shear onto the foundation, and when there is over designing of bearing pressure.

Different properties of soil at the foundation interface

Different parts of the foundation can rest on different properties of soil. For example, one part of the foundation can sit on clay, while another part of the foundation can sit on rock. When all design checks are adequate for one part of the foundation due to that part resting on good soil and when checks fail for another part of the foundation due to bad soil properties at the other part of the foundation, the whole foundation can fail.

Ground investigation will need to be used to determine these different soil properties. The foundation structure will need to be designed in consideration of the different soil stiffness and soil properties.

Source: https://cormsquare.com/

Insufficient soil compaction

The soil fill underneath the foundation might not be compacted properly and to its required degree of compaction. Since the soil is not compacted properly, air voids can be created within the soil, in which soil and water can displace in and out of. There will then be movement within the soil, which causes swelling and contracting. The swelling and contraction of the soil can cause pressure to the foundation that the soil supports.

Air voids within the soil can cause loose soil or soil with low density, which lacks adequate strength to support the foundation. Poor compaction equipment can also lead to foundation failure.

Therefore, it is best to compact the soil beneath the foundation to its required compaction degree before concrete placement of the foundation, in order to reduce soil displacement, to increase subgrade reaction and soil density, and to reduce differential and overall settlement of the foundation.

Source: https://frhi.sharepoint.com/

Uneven moisture levels of soil beneath the foundation

Similar to the above scenario, uneven moisture levels of the soil can cause soil swelling and contraction at specific parts of the foundation. This can lead to stress at intersecting locations where the soil is swelling and contracting and where the soil is not.

Changes in moisture levels of soil beneath the foundation

Moisture levels of the soil can change due to varying humidity levels, rainy weather, or poor drainage conditions, which can cause soil to swell (or heave) and contract, therefore leading to cracks. Similar to insufficient soil compaction, the voids within the soil can be filled up by water or other fluids, which can create pressure onto the soil particles from the fluid.

However, when there are dry periods, the water evaporates from the soil and leaves from the voids within the soil. This can cause soil shrinkage.

Moreover, when there are cracks within the foundation, water seepage can also occur.

Vibration from adjacent construction

Vibration from nearby construction can displace soil particles underneath the foundation. This can then create air voids within the soil, which can loosen up the soil and lower the soil density. The lower the soil density, the lower the soil strength for the support of the foundation. This will then cause foundation failure.

Transpiration

If there are trees adjacent to the foundation, the trees can evaporate the water from the soil into its roots and into the atmosphere. This can cause changes in the moisture level of the soil.

Next, we will explore the different remediation and prevention techniques.

But before we do that, are there any other causes of foundation failures you have encountered? Any examples that you experienced? Be sure to let us know in the comment section below!

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sturdy structural blog

Structural Engineering Blog: SkyCiv S3D

Working with S3D, Structural Analysis and Design Software In The Cloud, Anytime and Anywhere

Structural Engineering Blog: Foundation Failures

The Different Types of Foundation Failures

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sturdy structural blog

Structural Engineering Blog: SkyCiv S3D

Working with S3D, Structural Analysis and Design Software In The Cloud, Anytime and Anywhere

Structural Engineering Blog: Foundation Failures

The Different Types of Foundation Failures

About​

Featured in...

Categories

References

By using this website,​you agree to theTerms and Conditions.

About

By using this website,
you agree to the
Terms and Conditions.