Conventional MSE Wall Design Responsibility
Conventional MSE Wall Design Responsibility
(OP)
Hello Everyone,
Just received a project where several types of wall will be used. One of the walls is conventional (standard) MSE. Would like to clarify, who shall provide the design of the concrete panel in terms of the thickness and reinforcement? Also, who should design the steel strip length, number and type. Is that something kind of patent design the manufacturer have and he only the one shall design them or that is the responsibility of the structural engineer? In general, how is the design for standard MSE wall be handled?
Appreciate your input.
Thanks,
Just received a project where several types of wall will be used. One of the walls is conventional (standard) MSE. Would like to clarify, who shall provide the design of the concrete panel in terms of the thickness and reinforcement? Also, who should design the steel strip length, number and type. Is that something kind of patent design the manufacturer have and he only the one shall design them or that is the responsibility of the structural engineer? In general, how is the design for standard MSE wall be handled?
Appreciate your input.
Thanks,





RE: Conventional MSE Wall Design Responsibility
I dont know what you part of the wall you are referring to when you say concrete panel or steel strip length but the above companies would supply a complete service. They would not take responsibility for bearing capacity assessment so the consultant geo would have to confirm founding conditions.
Thats my experience anyways.
RE: Conventional MSE Wall Design Responsibility
www.PeirceEngineering.com
RE: Conventional MSE Wall Design Responsibility
Also, my above comment shouldnt have included "build". Tensar etc dont build the walls (as far as i know)
RE: Conventional MSE Wall Design Responsibility
www.PeirceEngineering.com
RE: Conventional MSE Wall Design Responsibility
RE: Conventional MSE Wall Design Responsibility
Good Luck!
EIT
www.HowToEngineer.com
RE: Conventional MSE Wall Design Responsibility
If you are part of the design, you can do a preliminary design in order to produce costs for budgeting purposes. I think that you will need to do this anyway in order to also allow the contractor to cost the project. Your drawings/specs can be performance-based (i.e. request for a minimum FOS). Then the contractor will choose a MSE wall contractor that can do the actual design and build the wall. The design can be reviewed by the design team.
On the other hand, I think that if you want to do the final design of the wall, it should be done by the geotechnical engineer who is part of your design team.
Bottom line, I think it will depend on how the project is managed. In my case, I do preliminary designs following the rules indicated above. It is also fun to be in the construction side, though !
RE: Conventional MSE Wall Design Responsibility
RE: Conventional MSE Wall Design Responsibility
However, there is a segment of transportation projects that are classified as design-build where the design-build team has responsibility for all facets of the project and will have to divide up the responsibilities for things like global stability among the team members. In almost all cases, the geotechnical engineer is the most qualified to do this work since they are in charge of the geotechnical exploration program and will determine what exploration and testing will be done.
The US private sector is completely the opposite of the transportation sector and everyone tries to pass responsibility down to the lowest levels on a project so that a person with a tractor is responsible for getting global responsibility checked on a wall he is building. Of course, there are no borings taken in this part of the jobsite since the geotechnical engineer was never retained to do any more work than the initial investigation where structures were not yet identified (I am being kind here to low bidders).
Back to the OP, proprietary wall systems (panels, blocks, etc) typically design their components for a given project but this requires a lot of trust. Specifications are necessary to determine for example the concrete used in the panels if the owner wants a strong and durable concrete panel. It would be like asking for a design-build driveway and not specifying the concrete material and letting the contractor choose for you. It all looks good for a year or two but what about 10 or 20 years? The same holds true for many aspects of the MSE wall design, you should understand all the key elements to be able to specify then check for conformance to whatever standards required or specified.
RE: Conventional MSE Wall Design Responsibility
pss: I think there is a difference in doing a global stability analysis and running global stability software. Any engineer can run software, a global stability analysis requires knowledge of a site, local soils, groundwater and the establishment of short and long term strength properties to make a reasonable assessment of stability. This is almost impossible to do well unless one is the geotechnical engineer and has been charged with acquiring the necessary information for a given retaining structure. This does not mean it is not done based on assumed soil conditions quite often but the results are only a guide and may or may not reflect the actual stability of wall structure.
Sorry to hijack the thread but this topic never goes away.
RE: Conventional MSE Wall Design Responsibility
EIT
www.HowToEngineer.com
RE: Conventional MSE Wall Design Responsibility
From my experience, the consulting geotechnical engineer has the responsibility for external and global stability and the wall-system manufacturer has the responsibility for the internal stability.
External stability relates to the stability of the reinforced zone when acted on by the external forces.
Global stability relates to the stability of the reinforced zone as it induces shear in the adjacent soil.
Internal stability relates to the forces acting within the reinforced zone.
I don't think of the latter as a design-build component. I think of it more as a shop drawing.
f-d
ípapß gordo ainÆt no madre flaca!
RE: Conventional MSE Wall Design Responsibility
Design-build transportation projects many times will have very limited geotechnical information and the full scope of geotechnical work is part of the design-build package. This makes it very difficult to prepare the cost estimates when no geotechnical issues or parameters have been established and it is beyond me how the contractors actually put the numbers together without huge cost contingencies.
The private sector is the opposite and treats everything as design-build for the most part with minimal geotechnical information available and everyone else is responsible for all soils issues on the project other than the owner. The number of private projects that are completed from preliminary geotechnical reports (defined as a handful of borings on a large site since there is no site plan developed yet) is quite amazing and one has to wonder what happened to good engineering practice to follow through with the real soils investigation. The minimum required to obtain the permits is all that is required in the private sector.
Just from my experiences...
RE: Conventional MSE Wall Design Responsibility
Out typical d-b advertisement will include some subset of geotechnical data. Perhaps 30 to 70 percent of what's expected by my program. The d-b imagines their bid price and gets an award. The responsibility to complete the geotechnical requirements of the program then shift to the d-b, who has to follow our book of words on minimum data requirements. They have 180 days to get their own compliant geotechnical engineering study completed.
When their geotechnical study is completed, we enter into scope validation where we will consider type 1 work orders - i.e., those that develop from incomplete information. After 180 days the d-b no longer has access to type 1 work order adjustments.
There is always recourse for type 2 work orders.
Our d-b projects consider risk management in that light.
f-d
ípapß gordo ainÆt no madre flaca!
RE: Conventional MSE Wall Design Responsibility
fattdad - 50 states and probably about that many different approaches. Sometimes it is a funding issue when money becomes available and a project is pushed forward on a D-B basis ahead of the engineering thus minimal data. I also refer to other transportation projects like mass transit that many times fall under a different section of the DOT (they used to be called highway departments). They are typically handled different than highway D-B projects. I have seen all kinds and some are much worse than others.
RE: Conventional MSE Wall Design Responsibility
This seems the logical responsibility scenario but as we see far too many in the world are not logical.