Response to a Reader Question... from 2007! About Billboards.

The e-mailer asked:
I was wondering if we could discuss billboards of the flexible type? I am a BS Geography student finishing my thesis right now and trying to find resource persons or key informants.
My thesis is about the hazards the billboards pose to human life and property. In line with my recommendations part, I wanted to seek alternatives on billboards, if not alternatives for the laws for it. Since I see that billboards can not really be wiped out, due to its economic contributions to the LGU or National government, your concepts are deemed vital.
The initial plan I have in mind is to interview you RE solutions we could make if and when billboards can not be banned totally.
Billboards proved to be something that can affect adversely the lives and properties of people. As a social scientist, I saw it very interesting to tackle but not really focus on the technical aspects of it. Flexibility is understood as a solution to the social problem.  
I replied:

I think you are using the term "flexible" differently from how I use it, e.g. as in an earlier paper I wrote
I can answer some of your questions and contribute to your thesis, and at the same time, clarify the use of the term "flexible" when talking about the structural or strength design of billboards. Actually, myself and my professor/mentor/thesis adviser believe that the term, "flexible," can really be confusing. What we really mean when billboards should be "flexible," is that the dynamic effects of wind should be properly accounted for in the structural design of billboards. When a structure is "flexible" it tends to attract larger dynamic wind effects, and thus, a stronger structure is required in the design. 
One thing I can tell you now is this. Dynamic wind effects has not been used in the practice of structural design engineers (of billboard structures) mostly because: 
First, it is not part of nor required by earlier standards for billboard structural design (e.g. the National Structural Code of the Philippines or NSCP, 4th ed., 1992, and earlier). 
Second, although it is now required in the current standard (NSCP 5th ed., 2001), a procedure detailing how dynamic effects in the design of billboards to withstand strong winds is not available. [NOTE: This reply was in 2007; the current standard is now the NSCP 6th ed, 2010, which already details the procedure to consider dynamic effects on billboards.]
Third, in the collapse of these billboard structures, the non-consideration of dynamic wind effects in the design of these structures is only one of many other possible causes. For example, the actual wind speeds during the typhoon may be larger than the design wind speeds. [NOTE: Per my recent research, the actual wind speeds in Metro Manila during Typhoon Milenyo were lower than even the basic wind speeds and much, much lower than what are supposedly the wind speeds at the onset of yielding or collapse.] Or, because wind is so complex and its effects are dependent on the quantity, size, shape, and arrangement of obstructions such as other billboards, buildings, and other man-made structures as well as natural terrain/topographic features, the state-of-the-art in defining the design wind forces could not really 100% accurately reflect that of actual wind forces. 
Of course, in engineering design, there are so-called "factors of safety" allowed.
So really, I believe that better engineering would result in stronger billboard structures that would not collapse even during strong typhoons. Better engineering may require better engineering education. 
Better engineering would also mean better engineering design of billboards, which is governed by the standard or code, which is, in this case, the current NSCP (5th ed). The NSCP could certainly use some improvement, as do most other codes and standards all over the world (even from highly developed nations such as Japan, USA, Australia, and those in Europe), again because wind is really a very complicated natural phenomenon that we are trying to define with very simple mathematical formulas. 
I also strongly believe that the NSCP could be improved by research. Research meanwhile requires time and funding. However, I don't personally think research, particularly in this field, is a high-priority interest of the general Filipino public, nor of the government. Funding and research in IT (info.tech.) seems to be more the priority. 
Between earthquake engineering research and typhoon/wind engineering research, there also seems to be more focus on earthquake engineering. But unfortunately, the facts tell us that typhoons have collectively caused more damage in our country. We have been promoting "typhoon engineering" though in the past couple of years. To reduct the effects of typhoons on people and property, we believe it will take a multi-disciplinary approach, and I am glad to hear that a social scientist such as yourself is studying at least this aspect of the billboards' collapse during typhoons. I may have to request for a copy of your thesis, when you have finished defending it. 
In any case, my MS thesis/research presented one suggested improvement to the NSCP, and hopefully it will be considered for the next update of the NSCP. [NOTE: This reply was in 2007; the current standard, the NSCP 6th ed, 2010, already includes my proposed improvements.]
Lastly, I would also like to mention that in most other countries, including Indonesia and Malaysia, they have functioning wind tunnel laboratories were wind and its effects can be simulated via scaled-down models of buildings, and whole metropolises. Unfortunately again, we don't have one - we used to have one in UP but I heard it is not working anymore. I have a source that told me they have one in PAGASA, but how it is being used, or if it is being used at all, and for what purpose, I am not so sure. 
So, I hope you have gained a better understanding of these billboards and their (structural) design, at least directly from an engineers' point of view.

By the way, with regards to your search for possible billboard alternatives, I have the following recommendations:
  1. Retrofit (strengthen) existing billboards that can be found by engineering analysis to be structurally deficient to withstand either design typhoon or earthquake events. 
  2. Use building facades (or those Edsa-MRT columns) instead for advertisement space. 
  3. Design new billboards considering dynamic effects, and other wind effects, as well as earthquake effects. 
I can't think of other alternatives right now. The thing is, you can use other types of structures as an alternative to the billboard structures right now which are of the lattice- or truss-type, but if the design strengths of these are not adequate, they will still collapse. So the important thing really is the (structural) design. 
There are other issues that you might be interested in.
  • I have heard that structural engineers are not paid so much for designing billboards. 
  • It is also possible that billboard owners, architects, or contractors, wanting to save in costs, sometimes instruct the design engineer, or the contractor, or the architect to use smaller and thus weaker steel materials, thereby compromising the strength of the billboard structure as a whole to withstand strong winds during typhoons.
I followed up in 2010 if he has been successful in completing his thesis work but I didn't receive any reply. If you know anyone who wrote a thesis related to billboards from back in 2007, please tell us about it.

No comments: