Who started M2 Consultants Inc. and why and what is new for 2022?

M2 was founded by Yogesh Prashar in 2004 after he works for several years with Kelinfelder Inc. in the role of the Numerical Modeling Practice Group leader. He realized after performing over 50 numerical modeling projects of varying sizes that he really enjoyed working on a wide variety of projects with multiple offices. He also realized quickly being in business for himself while doing something he loved and making (more) money while doing it made a whole lot of sense. He resigned from Kleinfelder then to start M2 Consultants Inc.

In the year 2022, Yogesh Prashar made the decision to resign from public service and pursue his passion of running M2 on a full-time basis.

Why is numerical modeling so expensive?

This is a very complex question and we will attempt to provide a general and simplified answer. Trying to solve static or dynamic engineering problems using finite element or finite difference methods can seem expensive. Numerical methods have been around for quite a while (1970s) and have seen a steady increase in use for projects of all types. The methods include the use of engineering software that is developed by engineers, scientists, geophysicists, programmers and researchers, and other experts in the field. The software is generally quite expensive and the professional's whing these tools are generally specialists in the field of geotechnical and earthquake engineering. Generally, the problems that require the use of these expensive tools are too complex to use simplified tools. The input data and material parameter definition of the boundary for the models are time-consuming to initially set up and also to "run" and "calibrate" properly. Often times these models will have reviewers (for good reason) to ensure the engineers performing the models have done their due diligence performing the modeling work. This review cycle can also add to the required effort and thus cost. Numerical modeling costs have been decreasing if one considers the improvements in models and value-added to models compared to past models' capabilities.

How do you know the model is correct, garbage in garbage out (GIGO), right? What are some precautions to take to avoid GIGO?

Yes indeed, GIGO! A very complex and loaded question and statement. In our experience following is a summary of things to look out for:

• Numerical models used should be tried and true and have been evaluated, calibrated, and tested by researchers, and practicing engineers.

• Engineers or scientists performing the models should be experienced and have some specialized training or experience in the field of geotechnical earthquake engineering.

• The material models or model codes for "stress-strain" relationships being used for all different materials should be updated by the software manufacturer or modeler.

• The stress-strain codes (constitutive models) should generally be widely used in the field by researchers and practicing engineers.

• If a static or even pseudo-dynamic (simple earthquake) problem is being solved then conventional methods should be used first and then only resort to numerical modeling.

• When performing a dynamic problem, again as mentioned above, use simplified solutions first or determine why the simple solution is just not applicable if it violates the physics of the problem. Unfortunately, sometimes modelers will try and "match" the numerical modeling results to simple solutions that are simply violating problem physics. Do not calibrate to a "wrong" method!

• The individual performing the model for the project should make sure the model 1) geometry, 2) material parameters, and 3) boundary conditions are correct.

• The modeler should have an idea of the limitations of conventional methods and why numerical methods are being performed or recommended.

• For dynamic problems, the modeler should perform a simple one-dimensional site response analysis using at least 2 different computer codes (see below) and compare the two for at least three acceleration or velocity time histories.

• Calibration should be performed in all model runs where material model modulus reduction and damping versus strain are compared for all materials within the models.

• Several "histories" of acceleration, velocity, and displacement should be recorded and evaluated to study the model response.

• If strong motion records are available for the site from historic events then the site response can be modeled to calibrate it against actual performance.

• This list can be exhaustive and perhaps will be extracted and expanded to a user group with open solicitation for all at a future date.

What computer codes are the best for numerical modeling in geotechnical earthquake engineering?

We have simply provided of list some more commonly used codes in no order and list suppliers. We do not have any affiliation with the suppliers and this is not an endorsement. No details are included for brevity and the links have comprehensive information:

• QUAKE/W: https://www.geoslope.com/products/quake-w

• SHAKE2000: http://www.geomotions.com/modules.php?name=Content&pa=showpage&pid=8

• DEEPSOIL: http://deepsoil.cee.illinois.edu/Files/DEEPSOIL_User_Manual_v7.pdf

• PROSHAKE: http://www.proshake.com/PS2.0Educational.html

• PLAXIS: https://www.bentley.com/en/products/brands/plaxis

• FLAC: https://www.itascacg.com/software/flac

Please e-mail us if you feel your product should be listed here.

How do we develop earthquake ground motions for a site, it use to be pretty straightforward, so why do we need to hire "experts" nowadays?

One doe not have to hire "experts" and can still do simply look up the codes and get the answer for your projects for many sites. The need for expertise comes when the site being proposed for development or modifications etc. meets the specific criterion. Since the mid-1990 there have been significant changes to the building code and we have been moving towards the development of performance-based ground motion parameters. In ASCE 7-16 (and IBC 2018) this changed from a "uniform Hazard Response Spectra" to a "Risk Targeted" approach. The codes also imposed the requirement upon the designer to make a conservative assumption of "Site Class D" for example if a site-specific characterization was not available.

The requirement to perform a site-specific analysis (site response analysis and ground motion hazard analysis was also increased compared to past codes. In future revisions to the building codes (ASCE 7-22 and IBC 2024) it is likely that the development of ground motions will get more complex than in the "early days" of code-based ground motion parameters.

Is "M2" short for anything and is there a meaning to the company name?

M2 Consultants: M2 is more like M*M or M^2 and is meant to be the short form for "Mathematical Modeling" applied to Geotechnical Earthquake Engineering practice. Additionally, the motivation for M2 was to match the first name of the owner's wife and daughter.

What's is M2's competitive advantage in other words why should we work with you over the competition?

M2 has been in practice since 2004 and its key staff is dedicated to tackling challenging practice-oriented problems applied to geotechnical earthquake engineering. Although we are small we are extremely focused and targeted and are experienced in performing the "right" amount of work without making academic research projects out of practice-oriented projects. M2 has clear and open communication with our clients in the initial scoping level meetings and develops the modeling approach, details, and outlines the limitations of the recommended scope of work to fit project requirements.

What is a better approach for site response analysis: equivalent linear or non-linear?

M2 has used both approaches on projects and in general although equivalent linear is simple, faster, easier, and more predictable than non-linear, the non-linear approach is better and more applicable for higher seismicity areas and also where soils are softer and can undergo loss of shear strength during seismic shaking.