not only bridges

How can civil engineers improve the sustainability of buildings?

There are some simple tips that can help improve the sustainability of our building solutions.

First of all, go for structures that are durable and avoid premature obsolescence. The most sustainable thing we can do is to provide structures that will be used for decades with simple and affordable maintenance. Replacing structures is expensive, so it is worthwhile finding out if their service life could be extended. Consider the enlargement, demolition and reuse of your structures. Good engineering consulting is to keep others -colleagues or clients- informed about more than the initial costs.

Then, civil engineers need to select the appropriate material which will not produce much harm to the environment, this is, using eco-friendly materials for the building. There’s a thin line between sustainability and locality. Sometimes the first step to sustainability is to choose materials which are locally found and widely used in the location. Consider minimizing the construction waste, noise and pollution on site. Also, try to understand the strengths of the local manpower and the traditional construction knowledge. Bear in mind that one size does not fit all and do your best to avoid the gross errors of the international style modernist movement.


Finally, adopt sustainable practices in your personal life and read about sustainability as much as you can. Craddle to craddle is a good book to start and get inspired. Whether our green proposals are accepted or not, we always have a chance to make a difference leading by example.

Photo: Bilbao Arena Miribilla, ACXT-Idom

Preferred geometry file for FEA: IGES, STEP or SAT?

IGES and STEP are the widely used neutral CAD formats and accepted in nearly all software packages.

IGES or IGS (Initial Graphics Exchange Specification) is the first CAD data exchange standard developed and it is capable of exchanging only geometry and topology information between different CAD systems.

STEP or STP (STandard for the Exchange of Product Data) enables storing, retrieving, sharing and archiving member data (f.ex. profie sections, material properties, etc...) throughout its life-cycle among different databases and STEP has become the industry standard for Data Exchange.

For Finite Element Analysis (FEA), preference for one or the other depends upon several things including:
1) the source CAD that is used to create the neutral format.
2) the target CAD, CAE or FEA package and the use for which the file is intended.
3) the kind and complexity of geometric elements included in the design (e.g., prismatic elements, splines, surfaces, etc.)

In IGES the output is in lines and surfaces while STEP file keeps the assembly hierarchy and output is a mixture of solids,volumes and surfaces. For FEA purposes IGES may be enough as you don't usually need solids/volumes. IGES works ok for importing beams and sometimes works well for plates.
For those that work in the 3D solid modelling world, STEP format may be preferred as it retains the solid geometry and brings the part into the 3D modelling software in solid format. In general STEP is also more robust than IGES for plates and shells imports.

ACIS SAT is very similar to STEP. The kernel of many AutoDesk and Dassault products is partially based on ACIS. For example Abaqus uses ASICS (*.SAT) as it's native kernel so I usually start there and then go to STEP and IGES would be the last choice.

Stupid as it may sound, I generally request more than one format and a screenshot image of what it should look like.

How do I validate FEA results?

First of all, check the numerical consistency of the results:

- Ensure convergence of solution: refine mesh and check if changes in the answer are smaller and smaller.
- As an error estimation look at strain jumps between adjacent elements with results not averaged or smoothed.

Then, compare to other theoretical/numerical results if available. Compare to empirical results if available. For hand-made engineering calculations I recommend MathCAD (or Smath Studio) instead of Excel because the formulas are readeable and with named variables.

Last but not least, compare with systems of increased complexity. For example, if you are analyzing 3D dynamic system with nonlinear material, start with 2D linear static and build confidence in your solutions by adding complexity step by step.

Monster bridge machine

The awesome mega bridge machine SLJ900/32 is being used in China for bridge girders construction.



The manufacturer is Beijing Wowjoint Machinery Co and the main features are:
  Weight: 580 tonnes
  Measures: 91.8 meters long - 7.4 meters wide - 9 meters high

Indeed, China is becoming a great industrial nation.

How to build a gas processing plant

This is an award winning short film for its educational value to the oil and gas industry. It is a pity that the video does not come with music. Included are construction methods, sequence, resources and timelines. Activities covered in the video are earthworks, pipe racks, slugcatcher, steel tanks, heavy lifts, welding & spool fabrication, pavements and fencing.

   

In the past two years, David H Moloney, an Irish engineer, has made and uploaded short films like this one onto YouTube showing us how civil projects are constructed. These projects range from airports, seaports, motorways and railways to oil and gas pipelines, metros, in-situ piles, bridge construction, post-tensioning, precast yard, quarry, roofing and more. I strongly recommend to visit his channel.