Monthly Archives: July 2011

bamboo tricycle

I want one!

Rather than using energy intensive processes to bend sustainable bamboo into shape post harvest, Alexander’s unique approach involves manipulating the bamboo stalks during the plant’s growth process. Tension is applied to the bamboo stalks as they grow over a reusable skeletal sub structure, that forms the structural basis of the vehicle. The natural energy from the plant does all the rest!

Splice (lap) lengths for ties in round columns

Anybody know what the splice or lap length should be for ties in reinforced round columns?

I would think it would be considered a class C splice in the ACI code. Somebody in our office also thought they should be considered top bars, I disagree with that idea.

If you look up this issue on the Internet it is pretty difficult to find a solution.

Thanks!

Arch ABC County Bridge Concept – Coffee Break Style

So I was thinking, how could I use high strength concrete in a ABC county bridge? Concrete in the range of 30,000 psi compressive strength. (206,842,718 N/sq.M)

Well I thought, an arch system, is the way to go, because arches are in compression, and concrete loves compression. So, on break, I came up with a really shallow precast thin arch panel bridge, which I think could be built quickly in the field.

Two problems (well lots of problems), one, the panels are the deck so you would have a “hump” on a road which could cause a fun jump at high speeds and two, I think you would need to post-tension parts of the bridge to keep the panels in compression. (Integral abutments can flex losing some of the compression forces)

I placed some tensioning strands on the outside of the bridge, so you could get at them and see when they need re-tightening. The panels would also have to have cross strands and shear keys to keep the deck working as a whole system. The railing could be the typical county rail that gets bolted on or you could place a slip formed rail, tied into the panels.

Okay here it is, and remember it might not work…….

Some more images……
Continue reading

Carmageddon!

Highway 405 in California is closed for the weekend, so they could remove the Mulholland bridge, a variable depth concrete bridge.

DBM winner

Meoowwww, the winner of the designbymany bridge competition is not actually a bridge….it is a series of dancing girls in front of a bridge. I’m not even going to give a link, you can find it.

Well designed, well presented but not a bridge concept. (yes I am the king of sour grapes)

Whats New

Things are a little quiet of the bridge front. I have finished my summer teaching ( I know you care) and I am waiting to hear about the fall. (teaching is outside my full time job)

I have also contacted a number of bridge engineers, hoping to start a series of short interviews for this blog. I thought it would be interesting to read about practicing engineers and their projects. (well maybe I will be the only one reading it…) But as you can imagine it is difficult to get responses to “cold” emails asking for answers to questions…..for a goofy bridge blog.

The idea was to ask five questions which would be short enough for a blog post, be interesting and manageable for a engineer to fit into their schedule. We will see how it goes.

What else? I have come to hate my usb Blue Snowball microphone. I can’t seem to get good sound out of it unless I am in a padded room and I hold the mic two inches from my face. (I believe that is two kilotonnes away for you metric types…) I wanted to make some “GOOD” videos for a change but, hey its the mic’s fault….(no really.)

One other idea I have been working on is a use for the ultra high strength concrete mixes out there, in “real” bridges, at an affordable price. We seem to use the stuff in traditional shapes (beams) and then pay extra for something we probably don’t need. An arch bridge is the way to go because it is typically completely in compression. I will work on it. (hopefully ABC)

hat-tip to David for some good photos.

Restoring Mont Saint-Michel

Hat-tip David.
An interesting project in France with a bridge!

Since 1995, when the French State and the Syndicat Mixte Baie du Mont-Saint Michel became involved, and subsequently the launch of the initial works in 2005, restoring the Mont to its marine setting has turned out to be one of Europe’s most original and remarkable site restoration operations. The European Union, which is contributing funding, has highlighted its dimension as a genuine sustainable development project to serve the area.

The main idea is to restore a marine setting to Mont St- Michel with tidal water all around on a regular basis, by using the combined power of the water from the incoming tide and from the River Couesnon. Reclaiming the sands in this way also means doing away with the 15 hectares of car and coach parks, as well as the causeway linking the rocky island to the mainland, as they have blocked the tidal currents for over 130 years.

The idea is also to have a completely new approach to the monument for the 3 million sightseers who come to see it, and often faithfully come again. From the mainland up to the Mont, a new approach road is to be constructed: you arrive at a parking area with reception and information services, 2.5 km (1.5 mi) from the Mont, and take the footpaths or public transport shuttle. You will then be able to taste the old spirit of crossing over to Mont St-Michel, taking the time needed to take in the bay scenery, stopping off at the dam then the pedestrian footbridge offering an unbroken view of Tombelaine rock, Mont St-Michel and the bay.

These new conditions of access to the rock will play a crucial role in controlling the influx of tourists. They will help to preserve, now and for future generations, the abbey approaches, a major cultural and spiritual destination, and the natural landscape of the bay listed as a Unesco world heritage site.

Ban Powerpoint?

A Swiss group (also part of an advertising campaign) want to ban powerpoint. I think engineers should join up.

According to the APPP, the use of presentation software costs the Swiss economy 2.1 billion Swiss francs (US$2.5 billion) annually, while across the whole of Europe, presentation software causes an economic loss of €110 billion (US$160 billion). APPP bases its calculations on unverified assumptions about the number of employees attending presentations each week, and supposes that 85 percent of those employees see no purpose in the presentations.

For a revival of innovation in civil engineering

Hat-tip David!

by Didier Brazilliers, Thierry Kretz & Jacques Resplendino

On a french website.

Key directions for innovation:
Four major orientations emerge, that can be combined into the design of the structure.

1 – Lightening and economising of structures by using high-performance materials;
2 – Use of renewable materials and with lower environmental impact;
3 – Design of structures with no maintenance or whose maintenance can be programmed by the integration of “intelligence” into the structure;
4 – Design of evolving structures that can be adapted as needed.

The first direction is to move towards building lighter structures by using of higher performance materials: self-compacting concrete with very high performance, high-performance fibre-reinforced concretes, steels with very high yield strengths can yield gains in materials savings of from 30 to 60% compared to conventional solutions, while further improving the sustainability of the structures.

The second direction is the use of renewable materials and those with lower environmental impact: it can be concretes formulated with a lower proportion of cementacious materials – higher performance being obtained by the optimization of the granular skeleton and the reduction of water content – or recycled aggregates; it can also be developed the use of organic materials such as wood and structural fiber reinforced polymers.

The third direction is to design works which need zero maintenance or where maintenance can be programmed by the integration of “intelligence” into the construction. In the field of bridges, there is the example of innovative solutions of integrated bridges that is to say built without the need for road joints, with no bearings required; these are items causing high maintenance costs and direct or indirect discomfort to the user.

There is also the possibility of avoiding the need for painting of metal structures by the use of “autopatinable” (self-weathering) steel or stainless steel, or to design innovative hybrid structures where the steel parts are fully embedded or protected by concrete. Predeflected beams with embedded spacers on the supports or at the concrete abutments are research topics in the National Project “MIKTI” and presented in this same issue of “Travaux”, are also good candidates because the concrete cover is maintained in a state of compression or under little tension in normal service conditions.

Integration of “intelligence” into works is done by equipping the construction with sensors and devices facilitating inspection and maintenance, like in motor vehicles (Eg: corrosion sensors or detection of the penetration of chlorides, combined with the use of contact protection cathodes).

The fourth direction is to allow the adaptation of structures to changing needs, for example increasing capacity, changing purposes, the extension of life, seismic strengthening, etc..
The design of new structures must include the possibility of flexibility of use and increased performance. On existing structures, new techniques are appearing to allow adjustments and needed reinforcements.

Free Software for Engineering Students

I am going to help out with a freshman engineering cadd class this fall. The construction engineers will be using Revit, the civil engineers, Microstation and all of them will be learning some Sketchup.

I’m sure your wondering why I go on about sketchup so much. I consider sketchup a gateway drug software program that allows and encourages engineers to explore new concepts.

Lets face it, engineers can not draw anything by hand. We don’t take classes that help us visualize our ideas on a napkin. We draw lines, which I think leads to simple line structures. I just taught a concrete class where most of the examples are based on line drawings that represent 3D structures.

All we do is draw lines….well try something new.

Free software for students:

Powerdraft by Bentley

MicroStation PowerDraft V8i is a professional-level application that maximizes your production drafting functionality:

Premier 2D/3D drawing-oriented solution for projects in all disciplines
Employs an easy-to-use graphical interface, intuitive viewing techniques, and an innovative set of industry-recognized tools for production work
Interoperates with other MicroStation solutions as well as with a wide variety of other applications, including the Google Earth™ service.

Revit and Autocad

Important Note :The Autodesk Student Version software incorporates all the functionality of our professional licenses, but includes a print banner making the software inappropriate for professional, commercial, or for-profit purposes. Autodesk Student Version software may not be used in the classroom or lab for instructional purposes, or for commercial or for-profit purposes.