Pedestrian Bridge
Pedestrian Bridge
(OP)
Technically I'm not suppposed to engineer this bridge. They will be replacing the main members and deck exactly as they are currently constructed so as to avoid having to bring it up to code:

My responsibility on the project is to simply document the process, draw an as built of the bridge and provide a scope of work (what members are being replaced etc...) The pilings were inspected and approved by some state agency and were deemed acceptable so those will remain.
In the process of replacing the main members the owner would like to do some minor upgrades:
1.) Provide strapping to secure PT glulam beams to pier system directly below.
2.) Provide strapping between abutting PT glulam beams for continuity and so beams have less chance of "walking" off of their bearing points. This pedestrian bridge services the golf course as well as pedestrian traffic so vibration from vehicles (albeit small) is something to consider.
3.) Provide some form of anchorage between the abutments (concrete) and the end terminal beams. Currently they are just bearing on a concrete ledger without any securing mechanism, see image below:

A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com

My responsibility on the project is to simply document the process, draw an as built of the bridge and provide a scope of work (what members are being replaced etc...) The pilings were inspected and approved by some state agency and were deemed acceptable so those will remain.
In the process of replacing the main members the owner would like to do some minor upgrades:
1.) Provide strapping to secure PT glulam beams to pier system directly below.
2.) Provide strapping between abutting PT glulam beams for continuity and so beams have less chance of "walking" off of their bearing points. This pedestrian bridge services the golf course as well as pedestrian traffic so vibration from vehicles (albeit small) is something to consider.
3.) Provide some form of anchorage between the abutments (concrete) and the end terminal beams. Currently they are just bearing on a concrete ledger without any securing mechanism, see image below:

A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com






RE: Pedestrian Bridge
If the "main members and deck" are in bad shape, what about the piling?
RE: Pedestrian Bridge
Being familiar with residential work and conventional light frame construction my first inclination is to turn to my Simpson manual. Whether this is a reasonable solution or not is somewhat of a question to me so I want to put it out there for others to weigh in:
1.) Secure beams to piling system with CS14 and 10d stainless nails
2.) Tie beams together at ends with strap nailed to one side of beam, CMST14 and 10d stainless nails
3.) Either a couple of DTT2Z into the side of each beam and a 5/8" all thread epoxied into the concrete abutment or some form of angle bolted into the bearing ledge and then into the beam.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
I think what you are describing would be considered design or redesign. I don't like to use "engineer" as a verb.
RE: Pedestrian Bridge
Of course he wants all this done by tomorrow and I am the only one in the local area that is willing to take it on with such short notice. So that is how I'm stuck with this one. Drawing up the scope of work and as built is a no brainer, I'm just a little uncomfortable recommending additional repairs/upgrades when I am not actually applying any numbers to it.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
RE: Pedestrian Bridge
pick one or the other.
another day in paradise, or is paradise one day closer ?
RE: Pedestrian Bridge
I think you've hit the nail on the head.
I just met with him about an hour ago to review a few last minute items to add to the scope of work. Specific design flaws in the original bridge construction caused the bridge to rot out (main members). This time around he will be taking measures to avoid those previous mistakes, so realistically there are some design changes but the hope is that these design changes are minor enough that it does not trigger a "new design" by the building department.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
Notice the end of the smaller beam, it has rotted to the point it is collapsing down on to itself, kind of scary to think they were just running 1,000 lbs golf carts across it a couple weeks ago.
Of course the major problem with the original bridge construction is the use of non-pressure treated glulams in a very wet environment (olympic peninsula, WA) and it is within a 1/4 mile of the beach.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
You ought to be applying some real numbers to the problem. This isn’t just the IRC in its lightest version, where you follow the cookbook and ask a bunch of questions on a forum, to form some engineering determination. If you haven’t got the experience to do this job, maybe you shouldn’t be doing it. Have you read that part of the engineering registration and stamping criteria which says you should only practice in areas where you have experience? Someone has to make an engineering judgement about the foundation of this bridge, its condition and the profile of the pile caps, or you’ll end up with about the same thing you have now, but with newer floor beams and decking. The City Bldg. Dept. is being chicken shit too, in saying replace it in kind or you need an engineer to stamp it. In their case, do they want someone with good engineering experience to evaluate the entire condition of the bridge, P.E. stamp or not, or are they only looking for a cheap-fee engineer who is really acting as the insurer of last resort, through his insurance coverage. There seems to be incredible misunderstanding, partly intentional in today’s world, about the duties, responsibilities and obligations of a registered engineer’s involvement in a project. Why don’t they go directly to a reinsurer if they aren’t willing to pay an engineer for his knowledge, experienced, time and judgement in bettering the outcome of a project? Hell, just go to the big box store, they probably have a program to sell material which will design this for them.
RE: Pedestrian Bridge
If I were doing this, the first thing I would want is to see the inspection report and approval by the "some state agency" who gave the pilings their blessing.
RE: Pedestrian Bridge
My responsibility now is to simply provide a scope of work for the replacement of the bridge main members, deck, and guard rails. I am also to provide an as built drawing of the existing bridge showing the location, size and length of each beam. Both the drawing and the letter will have a large disclaimer that there has been no attempt to provide any engineering or re-design of the bridge and I am not making any declaration as to is suitability or fitness for use of any purpose. Furthermore I cannot make any claim that the bridge meets or complies with any building or bridge codes (ASHTOO, IBC, ASCE etc...), in fact I will categorically state that the bridge in all likelihood does not comply with current code as it relates to lateral wind and seismic loads. Technically anyone could draw up these documents it does not need to be an engineer but the city official has required that a registered design professional provide them in order to issue the permit.
I appreciate your advice and insight @dhengr and @hokie66 on the liability and politics of the situation. I see your point where the city is probably trying to leverage some liability at some level from me even though I'm not working on this as an "engineer", at the same time appease the owner by giving them an easy out. Thank-you for helping to clarify this. Even with all of the disclaimers in place does it protect me from the liability if the bridge were to fail in the future? I guess the question is can an engineer really take a non-engineering role? I will consult with my mentor first thing tomorrow morning and make a determination on how best to proceed.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
RE: Pedestrian Bridge
www.PeirceEngineering.com
RE: Pedestrian Bridge
i'd vote to replace the bridge with a couple of "ski-jump" ramps ... just gun it !
another day in paradise, or is paradise one day closer ?
RE: Pedestrian Bridge
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Use the AASHTO Guide Specifications for Pedestrian Bridges either the Standard Specification version or LRFD version, depending upon the requirements of the AHJ. I would use the Standard Spec version if the substructures are to remain. The guide spec gives you the loading and vibration requirements; nothing mysterious about it. The design requirements for the timber would be based on the AASHTO Standard Specs, which more or less taken from NDS.
Railing is railing although AASHTO has a variety of loading cases to account for bicycles and pedestrians.
Tie downs are tie downs; use the AASHTO wind loads or even ASCE -07.
The USDA Forestry Service has a variety of publications and plans for timber bridges.
RE: Pedestrian Bridge
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
You claim to be a Professional Engineer, although as a Mech.E. you are kinda working outside your educational area and probably even your professional experience area, so you better start acting like a real P.E. You have to be able defend and explain this experience/knowledge situation/gap if the issue comes up, and it will if anything goes wrong with that bridge. Assuming you only do some measurements, drafting and comments about member condition, your work will still be judged as having been done by a P.E. (not just some dumb draftsman) you should know enough to sound the alarm if anything about the whole design does not measure up. You must know enough about the foundation conditions to do the design correctly. If the owner wants to save a buck, by not doing the whole thing right, he puts you in a pretty precarious position if anything goes wrong. But, don’t worry, all they can take is your house, your car, your savings, and your engineering licence, they can’t take the other tools of your trade. That is, your pencil and.... It isn’t the Bldg. Dept. which has a decision to make, it is the bridge owner who must determine that he will spend the money to make it right, and not leave you alone, hanging on a hook. The Bldg. Depts., these days, always swings a big stick, and assumes very little responsibility, despite their ignorance about anything other than the exact code verbiage. But, you have to guard against the owner trying to save some money by putting all of the responsibility and liability on your back.
RE: Pedestrian Bridge
I think medeek has gotten the message. Your last posts probably crossed.
medeek,
Good decision.
RE: Pedestrian Bridge
I have been doing structural work for almost two years now. Just because I started as an ME doesn't mean anything. I know two other practicing structural engineers who both began as ME's and ended up in the structural field. To be honest I feel that an ME actually has a better grasp of certain fundamentals that a CE might not. Whenever I encounter a project or potential project that is outside of my experience and comfort level I immediately consult with a couple of very experienced structural engineers who I have worked closely with the last couple of years. In certain cases I have ended up turning over entire projects to these more experienced engineers. In recent months I have tried to work out a joint program or a peer review arrangement. Unless I stretch myself and reach out to some of these projects I do not learn and my own progress as any engineer stagnates. The key of course is to gain more knowledge and experience while at the same time ensuring that the product I provide meets engineering standards, code and life safety issues. With peer reviewed jobs I typically make very little, most of it going to the consulted engineer, but that is the price of education.
I disagree, it is up to the building department to enforce the city building code and the law. Granted he may lean on me for some guidance but ultimately he is the law and if he allows the owner to proceed with a repair without a full engineered design that is within his power and jurisdiction to do so. If I were him I would insist that that bridge be brought up to current code or no permit. Unfortunately, the politics in this small town may unduly influence the decision.
If I disagree with their decision to simply repair the bridge as is do I have a duty or recourse that I can or should take, and secondly if I were to publicly disagree with this decision would it not simply be viewed as a conflict of interest since I am losing a potential job and money because of their decision.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
A 50 year old bridge in that location just must be life expired. How the city inspector has not simply condemned it I don't know.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Pedestrian Bridge
The city is not leveraging any liability, they are requesting a letter which hundreds of building department request when reviewing repair work. This is spelled out in the code, it is the responsibility of a registered design professional to determine the ability of the structure to withstand vertical and lateral loading and if the structure is noncompliant what is required to bring the structure to compliance. You do not have the qualifying experience or the stamp to provide this letter or make the evaluation. If you provide the letter or recommendations and an issue occurs you are responsible not the city.
RE: Pedestrian Bridge
@Sandman21
No, the city was not requesting a letter from me to assess the bridge and its current state, the decision was already made that they would not engineer it and they wanted documentation for the repair and as-built drawings as currently designed, any draftsman could provide that information. Trying to be helpful I let myself get caught and offered drafting services. Then the owner started plugging me for ideas with regards to upgrades etc...
Unfortunately, due to the economics and population base of the area I work a good percentage of my time is spent providing design and drafting services for residential customers rather than purely structural analysis. The upside to this is that I get to be involved with many facets of a project rather than being pigeon holed into a specific task. The downside is that the engineering sometimes takes a back seat to the design work.
I don't stretch myself on other's peoples dime, I stretch myself on my own dime. If this project were to ever land in my lap it would be a joint project with myself and one of my mentors (PE, SE) who has considerable experience with these types of bridges.
@LittleInch
This is why I post on this board, even though it is not always fun to take some of the heat from certain corners. The conversations are always quite lively and usually quite educational. Generally though I find it is often hard to get a consensus on a specific matter. You can ask the same question and get ten different answers, and they are usually all over the board and every shade of the rainbow. Even my two mentors, whom I absolutely respect, had completely differing opinions on this bridge project. Sometimes it takes a few heads getting together to get it right.
I think the reason this bridge was never condemned years ago was that no one ever actually looked at it and the owner kept applying small fixer uppers to keep it from having any major issues. There are numerous repairs and even some of the main beams have been replaced, all without permitting or approval. The first thing I did was condemn it and subsequently the City roped it off. It doesn't take an expert to say something is wrong when you can take a screwdriver and physically push it all the way through a 5-1/2" glulam beam. However, it did take a formal letter to the City citing life safety concerns before any action was taken. Given the state of the bridge I would say the repairs are 10-15 years past due, and the City is very lucky that there has not been a catastrophic failure which would have resulted in serious injury or death.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
This is part of the evaluation requirements for a repair with substantial damage, section 3405.2.1. You can’t know if the impacts are substantial or not without an assessment of the damage. You do not have the qualifying experience, or stamp, to make this determination. One of your “mentors” should have been reviewing the bridge and making the determination, with you providing the drafting, so that you could actually learn. This is the part that people have an issue with; you sold services which you are not qualified to perform. Any liability insurance you may have would not cover the damages should something happen.
If someone is paying you for the work that you are stretching yourself with, than it is there dime that you are learning on. You can’t have a joint project as it will be someone’s stamp and they would be the EOR.
RE: Pedestrian Bridge
After the decision was made by the owner and the City that a replacement was too costly and the best course of action was a repair they approached me for a scope of work and as-built drawings. I viewed these as a drafting assignment not as an engineering assignment, and mistakenly so. This effort was terminated by me shortly thereafter upon talking with my mentors about liability and what was the perceived intent of all parties involved.
In this whole episode the only money I have received is for my initial site visit to survey the bridge and for my letter to the owner and City.
On previous jobs I have worked with my mentor where I do the engineering and stamp it. They then review my work (drawings, calculations), typically ask a number of questions regarding various assumptions, sometimes provide corrections or alternative solutions based on their experience. Then at the end they compose a letter stating that they have thoroughly reviewed the packet and stamp and sign it. Is there something wrong with this procedure?
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
Even though I disagree with you on a few points you do bring up a good point with regards to how to address jobs that come up where experience or knowledge is lacking.
The vast majority of jobs I see usually involve residential or light commercial work involving convential light framed construction however once in a while something comes along that is either completely bizarre or somewhat outside my comfort zone. Most jobs can be categorized into the four following groupings:
1.) Knowledge and experience coincide with job -> Take job and complete it as the stamping engineer.
2.) Knowledge and experience mostly coincide with job -> Take job and complete it as the stamping engineer with peer review.
3.) Knowledge and experience do not coincide with job but want experience -> Work with other engineer on job or similar arrangement.
4.) Knowledge and experience do not coincide with job and do want experience -> Pass job on to other engineer.
However, sometimes certain jobs don't fit so nicely within the brackets. What is other's experience in dealing with this sort of thing. When can you stretch yourself a little but don't put yourself at risk. When and how do you draw the line?
I have found that education does not come cheap. I either end up having to spend a lot on other consulting engineers or I spend a lot of time and hence money in the books.
A good example is pole barn buildings. A year ago I had never analyzed a pole barn (only conventional framed structures up until this point) and then a job came along. On this one I took the study the books approach as well as contacted one of my mentors who allowed me to purchase some of his pole barn plans for study purposes. I went into the job thinking I could figure it out in a week. A month later I had finally figured out the details behind pole barn analysis, and came up with a nice spreadsheet calculator in the process. Unfortunately, the extra time taken to complete the job was just something I had to eat. The customer was inconvenienced by the time I took to complete the job but was forwarned that it might take longer than expected. In the end did the customer get an inferior product, I would submit that they did not. In fact, I probably went far and beyond the call of duty in my analysis because of my own insecurity and because I tend to be a perfectionist.
In a perfect world when I decided to cross over into the structural field I would have loved to find employment with a structural firm that had some SE's on board who could eventually endorse me so that I could sit for the SE exam. Unfortunately, our system does not look kindly on people that want to expand their boundaries. At 40 years old no one wanted a ME who is interested in becoming an SE. One principal I interviewed with came right out and told me that "Why would he want to hire a stamping ME and train him when he could easily hire a kid fresh out of college and pay him considerably less for at least 10 years". Even though I was willing to take a pay cut to make the transition I was mostly laughed at by all of the big and small firms I applied at. At 40 years old if you are not firmly entrenched in your discipline let's face it your "washed" up, or at least that is the message I was getting.
Luckily there was one engineer who was willing to take me on and offer me some jobs that were basically very low paying but enough to at least get my foot in the door. After quickly realizing (within a matter of two to three months) I was leaps and bounds ahead of this engineer and their methods I decided to strike out on my own. This has not been without some difficultly as I have had to turn away potentially lucrative jobs that were above my pay grade. After a couple of years though I'm now at the point where I feel I have enough experience to begin to push my education and reach out to more opportunities.
The point of this post is that as an engineer you should always be learning, if you stagnate you are retiring in my opinion. I am not just talking about learning the new provisions of some minor code cycle updates but also stretching oneself to better understand topics that you are currently not an expert in.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
I don't see how you can make such general statements about medeek's qualifications based on what he has told us. It sounds to me like he acknowledges his level of experience, and although he is a PE, he realizes that he still has some learning to do. Don't we all?
RE: Pedestrian Bridge
Medeek - your system is not unreasonable. Lots of people work at what are considered top notch companies and get little to no mentoring and very little oversight. Everyone has a different path into it but I'd bet a good portion of us taught ourselves just as you're doing, even if we weren't solo like you are. Most of us are still doing it in fact - why else are we asking questions here?
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Medeek, congrats on successfully pursuing your goals. I once heard of a "Dear Abby" advice column wherein the correspondent wrote something to the effect that he had always wanted to be medical doctor but now he was 36 and if he went to med school for four years, followed by another four years of residency, he would be 44 years old when he got out. Her response was to ask him how old he would be in eight years if he didn't go to med school.
RE: Pedestrian Bridge
With a mechanical background (and I assume a mechanical degree and sitting for the mechanical PE), the state board would probably say that your area of expertise is mechanical not civil/structural. To seal structural drawings, you should be a licensed structural (PE or SE). To be a licensed structural you not only need 4 years of experience under a PE/SE, but also the appropriate degree.
If you are not sealing the drawings and are simply contributing to the project under the supervision of the EOR, I think this type of project would be an excellent way to broaden your experience.
RE: Pedestrian Bridge
Medeek puts more thought and time into small projects than a lot of "high-level" engineers put into large projects.
RE: Pedestrian Bridge
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Jayrod12 you bring up a interesting point with regards to degrees and testing. When I took the PE exam in Oct. 2012 I had been out of engineering school since about 1996. The basic engineering stuff like statics and free body diagrams you never really forget but a lot of the other more mechanical specific topics I basically had to relearn almost from scratch, or at least if felt that way. Overall a very strange experience as I reviewed intensely for the exam (about 4 weeks) and slowly everything came back to me.
Now 4 years later I have been focusing and honing my knowledge and skills in the structural field and to be perfectly honest I doubt I could answer less than 50% of the mechanical questions that I successfully answered on the PE exam without some test preparation or review. This gives me some pause and makes me wonder how well do the NCEES tests really guage one's performance as it relates to practical engineering. The other important point it brings out that unless you are using specific knowledge on a daily basis that knowledge soon goes by the wayside. At the very least though, the test proves that you have good test taking skills and the ability to retain some knowledge to a certain degree no matter how briefly.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
RE: Pedestrian Bridge
To sit for the Civil/Structural PE exam in Washington either education with 4 years of related experience or 8 years of related experience (no education) would be necessary, at least that is how I am interpreting the rules. To obtain an SE only two additional years of experience is required and the type of PE you hold prior to the SE is not specificied.
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
I am an ME as well. I took the ME EIT exam but the Structural PE exam.
I now have 24 years of experience and have had the benefit of being able to do some ME jobs in the past.
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The big question, of course, is how much education/experience is enough. The answer is, that if something goes wrong, you didn't get enough.
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I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
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If that's the case then it's a sad commentary on the current state of civil engineering programs. But perhaps it's true. I've spoken to recent graduates who say that their departments have been overtaken by the environmental movement. They are now required to take so many environmental courses that actual design courses have been relegated to being electives only. It makes a mockery of the program and does a disservice to all. It used to be that a bachelor's degree in civil engineering was practical and sufficient to launch a young engineer into a design career, if he chose to pursue such. Less so now, from what I'm hearing.
RE: Pedestrian Bridge
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Pedestrian Bridge
Environmental engineers deal with things like waste management (both human and industrial) and impact on local ecosystems from new builds and all that kind of jazz. They do need an engineering qualification, usually a BEng or BSc, to do the job. I don't think this is a new thing, it's just another speciality that the civil engineers of old used to deal with save for the ecosystems stuff. I don't think anyone really gave that a thought back in those days.
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That sounds like the kind of name bin men come up with to sound more important.
RE: Pedestrian Bridge