2021 Seismic Design Competition

Clarifications

If you would like to submit a clarification request, please do so here: 

Clarification Submission Form

Please note that it may take a couple of days to be addressed.

 

General Questions

  • General Question problem 01: To what extent can we consider any retrofitting of the existing structure, both for deliverables #2 and #3? Can we add components or strengthen existing ones (eg. column jacking)?

    Retrofitting of the existing structure is not permitted for deliverables #2 and #3. This will be one of the primary components of deliverable #4, so it may be beneficial to brainstorm retrofitting options in anticipation of deliverable #4 based on your current analyses.

  • General Question problem 02: To clarify, the 5-Slide poster that is to be created on PowerPoint/GoogleSlides is just a singular slide with 5 different sections, like an academic research poster? Or is it 5 separate slides?

    We would prefer that your poster is 5 separate slides. This will allow for better viewing on a computer screen when you submit the 1-2 minute video overview of the poster slides.

  • General Question problem 03: How much time will we be given for the presentation and, given that the scoring rubric does not mention an Architecture slide, is it safe for teams to not include the section if we are to be considerate of time?

    The scoring document states that teams will have a maximum of 7 minutes for their presentations. Teams should mention architectural considerations that played a role in their design or may highlight an architectural challenge that their project responds to especially well. This would likely be beneficial when judges are scoring the presentation, but the focus of the scoring will be on the topics listed in the rubric.

  • Deliverable #2

  • Part 1 - Problem 01: When converting the given time histories to .txt, SAP keeps giving an error that the data is unreadable as a time history function. Is there any possible solution to this issue or potential to provide a .txt for the given time history data?

    Make sure you’re converting the time histories to .txt files separately for each scaled ground motion. They should be uploaded as separate time histories in SAP or ETABS. Otherwise, consider discussing with an advisor or looking at online resources to troubleshoot this issue.

  • Part 1 - Problem 02: Question 3 asks to consider the internal operation of the building. I am assuming that this part should apply to both the existing structure and the extension. Please confirm if this is the case. Thank you!

    Yes, this is correct. You do not need to consider the layout of the existing structure before the extension is added. However, the existing structure should be considered in conjunction with the extension after it is added. Because no prior layout is provided for the existing structure, it is up to the team to design the layout.

  • Part 1 - Problem 03: In the SDC – Existing Construction Documents, it is stated that the horizontal struts intersecting braces for floor 1 are “only located adjacent to and in-place of braces”. Does this imply that beams along the mid-height are not intersected by interior beams?

    At the mid-height of floor one (3” elevation from the ground), there are no interior beams. The horizontal struts at the mid-height of floor one are only on the exterior of the structure in the locations shown on the elevations. Interior beams do intersect exterior beams and braces at all subsequent floors.

  • Part 1 - Problem 04: Since only one Poisson's ratio value is given, is it assumed that the balsa is isotropic rather than orthotropic or should we be specifying material properties for each principal axis (This is in regards to defining the material properties in SAP/ETABS)?

    Just use the single Poisson’s ratio and assume that the balsa is isotropic. Although this is not entirely accurate, you may make this assumption for simplicity.

  • Part 1 - Problem 05: For inter-story drift ratio calculation for SAP users (since I believe ETABS has this already calculated), is there a location of preference to make these calculations? This question could also be reframed as reassurance that the diaphragm is still assumed to be flexible (and therefore not rigid nor semi-rigid as ASCE 7-16's third drift calculation criterion dictates).

    The best approximation may be to select the nodes at/closest to the Center of Gravity. This is one way of calculating the Center of Gravity:

  • Part 1 - Problem 06: For this part, do you want us to run the full time history analysis? Or should we input the time histories and tell SAP to analyze the data using a response spectrum analysis?

    The full time history analysis should be run for each ground motion.

  • Part 1 - Problem 07: For the design checks in Question 5 Part 1, which grade should we use when determining the size factor in NDS Table 4A for member capacity?

    You may assume a dimension lumber grade of No.1 for the purpose of determining the size factor.

  • Part 1 - Problem 08: Since the buildings diaphragms should be flexible and have zero stiffness, should we ignore torsional properties of the building or how should we account for this instead?

    Torsion should still be considered regardless of how diaphragms are defined. Torsion will likely appear in your mode shapes and it would be advantageous to attempt to
    minimize torsion in your design.

  • Part 1 - Problem 09: The deliverable states that Allowable Stress Design load combinations should be used when determining member forces, referring to ASCE 7 for the appropriate load combinations. Should we choose the combinations according to paragraph 2.4.5/pg.8-9 from ASCE? Could you give us more insight about these combinations, taking into account the fact that we are not familiar with ASCE and we want to avoid introducing wrong data in our SAP2000 model?

    Yes, you are correct that section 2.4.5 of ASCE 7-16 refers to the appropriate load combinations. Rather than calculating Ev and Eh using section 12.4.2, it is permitted to
    simply input the time history as Eh and neglect Ev. Additionally, you may disregard overstrength.

  • Part 1 - Problem 10: The deliverable states that we should report the maximum axial, bending and shear forces that are undergone by individual members. Does this mean that for each TH we need to check each member in our balsa wood numeric model in SAP2000 and report the maximum? Is this what individual members refer to?

    Yes, but only members with the highest axial, bending, and shear forces must be reported. This should be easily obtainable by viewing member force diagrams or output
    tables from the software. Note that in question 3, we are asking for the highest forces, but in question 5, the highest stresses will also depend on cross-sectional area, so we recommend that you find the peak forces in each type of member that has a different cross-sectional area.

  • Part 1 - Problem 11: In this part, construction details are required. Could you provide us a norm or a specific document in which we could find some regulations regarding this aspect?

    There is no required format to your construction details. We are primarily interested in your thought process and reasoning behind your construction sequence. Diagrams would be a good way to convey your ideas but there is no required format.

  • Part 1 - Problem 12: Can we assume that non-structural elements can close in the story to calculate the floor area (i.e curtain wall)? If so, can these elements extend past the tapered building shape as the figure shows in the structural design guide of the existing and addition (i.e building elevation - south)?

    Non-structural elements such as curtain walls are permitted to extend past the required footprint of the building. The plan dimensions specified in the design guide and
    drawings are for the purposes of constructing your numerical model. Any architectural features may extend outside of these bounds. However, please keep non-structural elements within reason (if they extend far outside of the structural bounds, then they would likely require additional structure outside of the structural bounds).

  • Part 1 - Problem 13: Assuming a Seismic Design Category D, which we had calculated in the Geotechnical deliverable, Section 12.5.4 of the ASCE manual allows using Section 12.5.3a or 12.5.3b to satisfy the additional requirements of the low Seismic Design Category. The first is to design for “100% of the forces for one direction, plus 30% of the force in the perpendicular direction”. The alternative option is to have a simultaneous application of orthogonal ground motions, which would result in only 4 analyses. Since the SLC instruction asks us to analyze each direction separately do we use 12.5.3a or do we simply apply 100% of the force in only one direction?

    For this deliverable, please just apply the 100% of the force in only one direction

  • Part 2 - Problem 01: Regarding the addition, should we make it from the upper floors of the building already created (tenth floor onwards) or should we make a different building next to the one already created?

    The Addition should be on top of the existing building

  • Part 2 - Problem 02: In Table 1.0 of the SDC - Structural Design Guide, two elastic moduli are presented: E and Emin. How should they be applied to the analysis? Are we expected to test both values for our Modal and Time History Analysis or are they used somehow to represent variability in the balsa stiffness?

    E should be used in your ETABS or SAP2000 models. Emin should not be used in your numerical model, but may be used in addition to E when determining member capacities according to the NDS. Equations in the NDS explicitly call for E or Emin.

  • Part 2 - Problem 03: Is our addition (and future retrofit, including all bracing, etc.) restricted to a set footprint/the footprint of the existing structure?

    Please refer to “2021 SDC Structural Design Guide” for all the details regarding the extension building geometry, member sizes and spacing requirements.

  • Part 2 - Problem 04: What is the total duration of construction for the addition (ie: 4 years, etc.)?

    This is something up to the designer; however, the addition should be constructed as fast as possible within a reasonable timeframe and ensuring that the existing hospital structure is functional.

  • Part 2 - Problem 05: Is our addition (and future retrofit, including all bracing, etc.) restricted to a set footprint/the footprint of the existing structure?

    Yes, all parts of the existing structure and the addition should be restricted to the set footprint of each floor, as outlined in the provided drawings.

  • Part 2 - Problem 06: According to the deliverable, ‘a thorough analysis of the structure with the addition is not required in this deliverable’. Does it mean that we need a SAP2000 model for the existing structure and another model for the additional structure, respectively, or do we need a model which contains both structures together?

    For part 1 of the structural deliverable , your results should be based on your SAP/ETABS model for the existing structure only. For part 2, the addition should be
    incorporated into your existing model and the two components should be modeled together. For any future questions about the additional structure, analysis should be conducted based on your SAP/ETABS model that has both the existing and the addition structure together.

  • Part 2 - Problem 07: Should the addition be treated separately from the existing structure? If so, please confirm.

    No, please consider the addition and existing structure as a single building in part 2 of the structural deliverable. In reality, the additional structure will be put on the existing
    building to perform together in an integral way

  • Part 2 - Problem 08: This section notes "Use drawings to describe how connections will be designed between the addition and the existing structure and how connections will be implemented within the addition itself." Does this mean we are to design steel connections or balsa wood for the drawing package

    We would like you to design balsa wood connections for this part. The structural drawings in part 2, question 3 should all correspond to a balsa wood model.

  • Part 2 - Problem 09: The Deliverable mentions "Your company has been tasked with designing a structural system that will accommodate this tapered geometry without altering the existing hospital structure." If we had determined poor performance in part 1 where the structure would be at risk of failing, are we only to look for acceptable performance of the addition under the assumption that the existing structure will be edited and fixed in deliverable 4, or are we to make a structure that is expected to stand in this deliverable?

    Yes, this is correct. In this deliverable, we are asking for a preliminary design for the additional structure that you believe will perform well with the existing building once the
    existing building is retrofitted.

  • Part 2 - Problem 10: Is it allowed to use shear wall in the extension? since it is mentioned that we will be able to revise the existing building and make changes so that the shear wall connects the entire building.

    The use of shear walls is allowed, however, as mentioned it should be connected to the existing building foundation (in the final version of the building).

  • Deliverable #3

  • Part 1 Problem 01: We were wondering in the LEED question if we are going to send a scoreboard with checked applications we did in our design, or we should just mention our environmental design decisions in general? As there are missing data that are needed to fulfill LEED prerequisites.

    Teams should say how they will apply the points mentioned in the scoreboard in the LEED official website in a practical way in their designs, not just tick or check the points in the scoreboard.

  • Part 2 Problem 01: What scale should the architectural model be done at? 48” to 1” on paper (1:48)? 96” to 1” on paper (1:96)?

    The scale of the architectural model is up to the discretion of the teams. The only requirement for the scale of the model is that the render and drawings fit on size 8 ½” x 11” paper.

  • Part 2 Problem 02: For the architectural model, what should we assume the structural member material to be? For example: glulam, steel or concrete?

    For the architectural model, you can assume any material that you think would be appropriate for the members. Balsa wood is required for the structural model, but there is no specified material requirement for the architectural model.

  • Part 2 Problem 03: The deliverable asks for 4 pages, but also asks for floor plans and renderings. Do the floor plans and renderings count toward the page limit, or should we just make these images very small? Since floors 12-19 have different dimensions, does each level need to be inserted into the deliverable?

    For Deliverable #3, only architectural renders and schematic drawings are required. The floor plans for the addition is part of the structural deliverable.

  • Part 3 Problem 01: What are the scaled-up dimensions of the floors in terms of how big the real building would be? This would be helpful for choosing room sizes for the internal floor plan. How many floors do you want schematic drawings for?

    The floor dimensions of the real building are up to the discretion of the teams. As an approximate range, you may consider about 2000 to 3000 square feet when deciding the layout of the internal floor plan. Include schematic drawings for whenever the layout of the floors changes. If you have a repetitive floor plan, simply label it with the floor levels it applies to. Teams may use their judgment to decide the number of schematic drawings needed to adequately convey their ideas.

  • Part 3 Problem 02: What is the scale of the structural model? We need this information in order to determine the appropriate internal layout of rooms in the building.

    There isn’t an exact linear scale of the model to the real building. When determining the internal layout of rooms, consider a floor area of approximately 2000-3000 square ft, but you will not be penalized for going outside this range.

  • Part 3 Problem 03: We are aiming to achieve a LEED BD+C Healthcare certification. Does this certification apply to the whole hospital (existing + extension) or just the extension? If it applies to both parts, should we assume for instance materials used for the existing to achieve the certification? Thank you again!

    Consider both the existing and extension parts when aiming for the LEED certification. You may make an assumption for materials or put more emphasis on LEED points that are independent of material type.

  • Part 3 Problem 04: Access points are listed as 1"x2.25" in the Design Guide, however, in our scaled-up version to real-life dimensions, an access point in internal hospital renderings is roughly 6ftx13.5ft. Do the access points from the structural requirements have to be maintained in the architectural rendering? For example: when completing the renderings and internal operation of the hospital, do we need to provide hallways/doorways to match the size and location of our access points (eg. 6ftx13.5ft) , or do hallways/doorways in the rendering need to match the location only of our access points?

    Your structural configuration should be taken into consideration when completing this part of the architectural deliverable. For example, you should consider where columns
    and braces are located in the floor plan and where your access points are located. However, the dimensions of your access points in the real structure may be adjusted to accommodate the functionality and architectural interests of the hospital. Strict adherence to dimensions of your balsa wood structure is not required.

  • Deliverable #1

  • Part 3 - Problem 01: The deliverable rules state that we should assume a site class of D. Do we assume that this site class was calculated using the “future geophysical tests following liquefaction mitigation”, or are we just assuming site class D because we are not sure what the actual future site class is?

    The site class of D was determined by performing additional in-situ tests after the liquefaction mitigation methods were performed.

  • Part 3 - Problem 02: A site class of D is assumed for this part. Using ATC hazard tool parameters such as S1, Ss are to be obtained. However, in the tool drop-down menu there are two site class D options (stiff soil-default). The two options provide the same Ss & S1 values, but the other parameters’ value are different. So what’s the difference between site class D(stiff soil) & site class D (default). And how is it possible that they both provide the same values for parameters Ss and S1 but different values for the other parameters?

    The difference in choosing site class D (stiff soil) and the site class D (default) is stated in ASCE 7-16 section 11.4.3:”where the soil properties are not known in sufficient detail to determine the site class, Site Class D … shall be used unless the authority having jurisdiction or geotechnical data determine that Site Class E or F soils are present at the site”. The “default” selection (based on insufficient data) is typically more conservative in its values than the “stiff soil” selection (based on the available data). Because shear wave velocity data is available near the project site, it can be assumed that we have sufficient data.

  • Part 4 - Problem 01: The deliverable for Part 4 Q1 states to “Fill in the rest of the inputs with the information already provided”. when inputting the Site class on the USGS website, should the Site Class found in Part 2 be used, or should a site Class of D be used (as noted in Part 3 to use Class D for all subsequent calculations)?

    Use Site Class D.

  • Part 4 - Problem 02: The deliverable states that we have to provide screenshots for the deaggregation plots for T=1.00 s to T=2.00 s. Several plots were provided for spectral period 1.00s: hazard curve, uniform hazard response spectrum, and spectral acceleration for 1.00 s. which ones need to be provided in the final documentation?

    Please provide a screenshot of the deaggregation plot only. This is the 3D bar chart.

  • Part 4 - Problem 03: The deliverable states that on the given website we introduce the information already provided in the previous points. What diagrams are expected to be plotted and which option do we have to choose? (total deagregation, source:fault, source:grid, source:slab and source: interface) our solution:from the spectral period we chose peak ground acceleration and total deaggregation and provided screenshots with the diagrams.

    Please plot the “total” deggregation for the spectral periods that we specified in the deliverable (not at PGA).

  • Part 4 - Problem 04: As our National Code and Eurocode show little resemblance than ASCE, could you provide us some supplementary information about ‘others’ category?( what is the precise meaning of grid/slab/fault etc.)

    These are all potential seismic sources that are mapped and considered in the hazard calculation. Interface and slab (sometimes labeled intraslab) sources indicate the location of a source relative to a subduction zone. Faults represent seismic sources from known or mapped faults. Grids indicate potential background seismicity not related to a known fault, and use an algorithm to smooth this data over gridded coordinates.

    Details regarding gridded seismicity can be found here:
    Frankel et al. (1996). “National Seismic-Hazard Maps: Documentation.” Open-File Report 96-532, Denver, CO. June 1996

  • Part 4 - Problem 05: According to the deliverable, Grid, slab, and other sources without a defined m and r should be grouped in the “Other” category. Should we change the component to source:slab/grid/fault etc. in order to complete the ‘other’ category in the table?.

    The “other” category can be evaluated by leaving the deaggregation as “total.” All remaining percentages without an m and r value can be added to make up the “other” percentage.

  • Part 4 - Problem 06: Should we consider the ‘other’ category (slab, grid etc.) together or each one of them separately in the table? (for example, at T=1.00s, for slab we have 3 different values and for grid we have 7 different values; do we have to list each one of them or add them?)

    Please just add them together and present the total only. There is no need to distinguish between these sources for this assignment.

  • Part 4 - Problem 07: It is stated that “Grid, slab, and other sources without a defined m and r should be grouped in the “Other” category”. Just for example, for T1 – the deaggregation results on the USGS website do not show a defined m and r for two source sets with the type “fault”. However, when the deaggregation report is download, the m and r are given for them. Should this be counted/not counted as having a defined m and r?

    That part of the assignment should only be referring to what appears on the webpage, not the downloaded report. Please keep those fault sources without m and r presented on the webpage (such as “Geologic Model Full Rupture”) in the Other category. These are expected to be minor sources and may not always represent actual mapped faults.

  • Part 5 - Problem 01: The data from PEER and the data from the given seed motion spreadsheet seem to have different time scales(i.e. The independent variable, T, has different sets of values for the two different sources. Are we expected to manipulate the PEER data and/or modify the spreadsheet?

    You are not expected to manipulate and /or data or modify the spreadsheet. The given seed motions’ period (T) and pseudo-spectral acceleration were obtained using a different  method than what PEER is using, hence the discrepancy in the T values. it is okay to use a different set of T values for the response spectrum obtained from PEER.

  • Part 5 - Problem 02: Since we can’t change the given excel for the four ground motions, the values of the selected ground motion from the PEER will correspond to a smaller time range which will not even reach T=1.0 sec for scaling purposes. Also, the geomean values will not be accurate. I want to make sure that you’re aware of this problem.

    See answer to question below.

  • Part 5 - Problem 03: When populating the section on the spreadsheet designated for the PEER database ground motion, the discrepancy in the scales of the period between the seed motions and the PEER motion causes the values of the Geomean to populate incorrectly. In this case are we to input the PSA values according to the period values given for the seed motions or remove these values from the Geomean altogether?

    Yes, we did not foresee this issue with the geomean. Please use the period range provided by PEER for the response spectrum only. Still provide a plot with your scaled geomean using only the four provided seed motions.

  • Rubric: The rubric mentions a 12 page limit (included title page, excluding references). Would any appendices holding referenced tables and sample calculations be included in this limit as well?

    An appendix with sample calculations and referenced tables will count towards the 12 page limit. We are primarily interested in seeing your final answers and/or recommendations to the stated questions, with only the necessary supporting information. The
    reference section should only include citations of referenced resources.

  • Rubric: The rubric states that the title page should include a computer-generated image related to the deliverable. Does this requirement apply to the first deliverable, where we are not required to generate any renders or models? If so, what kind of imagery is expected?

    Since this deliverable is not as graphic-heavy as later deliverables, the image can be considered as optional.

  • Deliverable #4

  • Part 1 - Problem 01: the Design Guide notes that "rentable floor area may only be within the continuous perimeter beams of the floor" (page 5). When calculating the total rentable utilized floor area of the structure, do we calculate the area from the centerline of the perimeter beams of the floor or from the inner edge of the perimeter beams of the floor?

    We would like you to use centerlines of perimeter beams when determining the total rentable floor area of the structure.

  • Part 1 - Problem 02: The deliverable document specifies page limits for calculation appendices and drawings. If our drawings/appendices take up less pages than the limit, can other sections of the report be extended to use up the extra space, or are those pages reserved?

    Yes, you may adjust other parts of the report as long as the total report is within the 11-page limit. Please only use 11×17 size pages for drawings (i.e. if you use fewer than three pages for drawings, you may not use an 11×17 page for the body of the report).

  • Part 1 - Problem 03 (part A): Does the member requirement of 0.2”x0.2” max area specified in the Design Guide apply for the applied retrofitting scheme technique? For instance, can the designed bracings on the extension structure done on Deliverable 2 be retrofitted to have a total dimension bigger than 0.2”x0.2”? This is technically retrofitting the proposed initial design and not proposing a new design.

    We would like you to stay within the specifications of the Design Guide for all parts of the addition. You are permitted to deviate from parts of the Design Guide for the existing structure because you’re restricted by the original design of the structure. With the addition, however, you have the ability to completely adjust the design of the addition and should therefore be able to come up with a configuration that meets the Design Guide criteria.

  • Part 1 - Problem 03 (part B): As part of the retrofitting scheme, can the existing column dimensions be increased to exceed the 0.2”x0.2” specified area from the Existing Construction Documents?

    Yes, you are permitted to increase the column dimensions of the existing structure as part of the retrofit scheme. However, if you choose to do so, please describe how this represents a real retrofit technique.

  • Part 1 - Problem 04: This deliverable states that we are asked to use flexible diaphragms for the existing structure (Deliverable 2 states that "Diaphragms should be completely and have zero stiffness"). Taking this into account, we considered that for the analysis of the existing structure the rigid diaphragm condition was neglected and we did not use diaphragms (wall members/slab), as it was not imposed . Is it correct ?

    Yes, this question in Deliverable 4 asks you to consider how the modal results will differ when you change the initial Deliverable 2 assumption and impose a rigid diaphragm.

  • Part 1 - Problem 05: The deliverable states that the assumption of flexible diaphragms with zero stiffness should be changed with the rigid diaphragm condition. Does it mean that for our numerical model in SAP2000/ETABS a certain thickness diaphragm should be introduced in order to satisfy this assumption ?

    Because you are assigning rigid diaphragms rather than semi-rigid diaphragms, the thickness that you assign to the slab element should have little consequence on the behavior of the structure. Rigid diaphragms have infinite in-plane stiffness rather than considering the actual in-plane stiffness, so the slab thickness would not affect the behavior.

  • Part 1 - Problem 06: If the retrofitting scheme includes structural dampers, do we need to provide a method of proof as to how we could have built a scaled damping members with the properties we input to the SAP model? The main problem being the confirmation that our proposed member design would have the properties we suggest.

    If your retrofit scheme includes dampers, then yes, please provide information about the properties of the dampers that you input into the ETABS/SAP model and how those properties relate to dampers that could be constructed in a physical balsa wood tower and/or how the dampers are similar to dampers that are implemented in real structures. 

  • Part 1 - Problem 07: If we were to consider a retrofit design similar to BRBFs, is the dimension limitations specific to the member in its entirety or to each of the materials considered in the design of this member?

    For any retrofits applied to the existing structure, you may deviate from the dimension limits of the Design Guide in order to simulate a real retrofit technique. When considering a BRBF-type member, you may choose to stray from the dimension limits for the entire composite member or for each of its components, but please provide justification for how this would relate to a real BRBF and/or how it could be constructed in a physical balsa wood tower. It may be more appropriate with BRBFs to adjust the material properties rather than go outside the dimension limits.

  • Part 1 - Problem 08: The definition of existing structure is unclear. When replacing flexible with rigid diaphragms, does existing structure include only the first 10 stories, or all stories on the existing structure with the addition?

    For this question, change the diaphragms from flexible to rigid for all the levels from the bottom floor up to the 10th floor (roof of the existing structure). Keep the diaphragms of the extension (11th floor to roof level of the addition) flexible. You are asked to compare mode shapes of this configuration to mode shapes of the structure with all flexible diaphragms.

  • Part 1 - Problem 09: When applying density to our model in deliverable 3, we accidently applied as weight per unit volume rather than mass. However when changing this value, our model yields very low displacements and forces. We would like to confirm that the 8 pcf value is in fact weight per unit volume for our final model and analysis

    The 8 pcf value is the weight per unit volume for the balsa wood members. This is similar to mass per unit volume but expressed as a specific weight rather than a density. Make sure that in addition to this self weight of the balsa wood members, you apply a dead load of 1.44 psf to all floor areas. This dead load should be included in the seismic mass of the structure and therefore be activated as a lateral force when conducting a modal analysis or running a ground motion. If the 8 pcf self weight of the balsa wood is the only load considered in the analyses, your results will have very low displacements and forces. This could be the issue, but also keep in mind that a small-scale balsa wood model would have much lower displacements and forces than a real structure

  • Part 1 - Problem 10: If we make changes to our addition from what we submitted in Deliverable 2, what should we use for the D/C checks in Part 1-1? (1) The deliverable 2 addition plus existing structure OR (2) The addition that we're currently working on, plus the existing structure but not including the retrofit of the existing structure

    Because this was not clear in the instructions and the question and response were posted very close to the submission deadline, either of the above checks will be acceptable. However, we would prefer option (2) as a more direct comparison between the unretrofitted and retrofitted conditions.

  • Part 1 - Problem 11: Our final construction drawing shows every member in a single line and then states the thickness of each type of member in notes. When we calculate the weight of our design, can we still subtract out the weight of the overlapping connections to make it actually accurate? Or will you guys not account this reduction due to connections? We found that subtracting out the redundant volumes for connections can potentially make a 5% difference, which can mean getting a penalty or not.

    For the sake of simplicity, we would prefer that this reduction due to overlapping connections is not taken into account when determining the weight of the structure. Also, consider that if you’re measuring lengths of members from centerline to centerline of perpendicular members, the overlapping member volume on the inside corner of the connection would be picked up by the missing volume on the outside corner of the connection so it would be more accurate to not include any reductions. This calculation becomes more complicated for braces and non-orthogonal geometries and it may be more accurate to apply the reduction for redundant volumes in these cases. If you do reduce weights because of overlapping volumes, we just ask that you clearly state this in your report and provide any example calculations to prove the accuracy of your reduction.