Questions submitted for the 2017 EPD Competition
Q: If the weight of the EPD is a little (around 10 grams) more than the maximum allowable weight (3500 grams), will it be accepted with a penalty or disqualified? Also, if the dimensions are exceeding by 3-4 mm above the specified maximum limit, what would be the consequence?
A: Typically, if a submission does not conform with the rules, it is disqualified, though the decision is ultimately up to the judges. We would recommend making the necessary modifications to the EPD prior to arrival at the competition so that it meets the requirements of the rules.
Q: If the longitudinal reinforcement placement (taking in consideration that the angle respect the horizontal plane of the reinforcement is greater than 30º), would it count against the maximum stirrup number as just 1 stirrup or as 2 stirrups?
A: As shown in figure 1, reinforcing is accounted in 2 dimensions. For sloping longitudinal reinforcing qualifying as stirrups, reinforcing in the same plane will only be counted once. In this example, the 2 sloped longitudinal bars would count as 1 stirrup.
Q: Does the maximum weight need to be 3500 g for the EPD, or will the judges allow a range of 20 g or 50 g more?
A: The rules provide the target parameters along with any tolerances, if there are any. It is also important to consider the possibility of the variability between different measuring equipment. It is dangerous to fabricate to the edge of the rules and assume that different measurement equipment will reproduce the exact same values as those used at the fabrication facility without some slight variability.
Q: For the reinforcement, will the judges be strict to the permitted diameter of 1.6 mm, or if the reinforcement diameter is slightly higher, will the participants be allowed to continue the tests?
A: The site judges will have the ultimate decision; however, it is likely that designs that do not meet the rules will either be disqualified or at least penalized.
Q: When the rules mention that the reinforcement should not be visible, do they refer to all types of wire including lashing, or only longitudinal reinforcement and stirrups? How strict will the judges be with visible reinforcement?
A: The ultimate decision will remain with the site judges, but designs that do not meet the rules will likely either be disqualified or penalized.
Q: Is there any restriction on the angle of inclination of the stirrups? Or can these be placed the way we want?
A: Judges are not able to review and approve individual cage designs. The rules state reinforcing requirements in Section 2d. Restrictions were placed on size and number, but not on specific placement or orientation.
Q: For Figure 1 in rules, about the footing, is it permitted at any side of the EPD, or only external as shown in Figure 1 of the competition’s rules?
A: Restrictions on the geometry of the EPD are located in rules Section 4. Orientation in Figures 1 and 2 are hypothetical designs used to demonstrate the written rules.
Q: Can we use a copper/ brass wire for tying the stirrups?
A: The rules do not specify a material type for tie wires.
Q: Would a single bar bent at 90° at the junction of the horizontal and vertical member that is primarily longitudinal in both be considered a stirrup in the other?
A: No. See Figure 1 for an example of rebar accounting.
Q: Are the stirrups what we believe to be a stirrup in a traditional sense? Such as a U shape or a box shape or are they a single straight piece in a perpendicular orientation to the long bars?
A: Both would count as a stirrup. Some examples of stirrup designs are depicted in the FAQ section of the ACI website for the competition, but standard stirrup designs are commonly used in the structures. Stirrups can and have been simple or very complex.
Q: What is considered a smaller gauge tie wire? Can we use the smaller tie wire as a spacer/hanger for the longitudinal bars?
A: If the judges consider the tie wire of sufficient size/quantity to add reinforcement to the structure, the students risk them being counted as reinforcing - stirrup or longitudinal as appropriate. Often, students use 26-30 gauge wire that is commonly used for jewelry making and is available at hobby stores as the small-gauge wire.
Q: Is it allowed to weld a wire with a lesser diameter around the longitudinal wire reinforcement to give it adherence?
A: Please pay careful attention to Rule 2d for all reinforcing steel design requirements. Please note that "No... welding of cages is permitted."
Q: In the following image, we show the EPD's reinforcement. Can you tell us if we are following the requirements of the rules?
A: The committee does not have the ability to review and approve reinforcing designs. Please pay careful attention to Rules section 2d and Figure 1.
Q: Can we use fibrous agreggate to mix our concrete?
A: All aggregates but steel are allowed; however, if the judges see the fractured specimen and interpret the aggregate as fibers in the mixture, the team risks being disqualified as fibers are not allowed.
Q: How many EPD's each team is permitted to bring to the student competition?
A: Only one EPD may be submitted per team.
Q: Is It allowed to use two different concretes, one on the column and the other on the beam?
A: Two different mixtures can be used within the structure of the EPD as long as it meets the requirements of the rules and both of the mixture designs are within the submitted report.
Q: What is the height from the top of the egg to the base plate?
A: Refer to Rules Section 4 and Figure 2 for required size for the EPD. Eggs will likely be of different sizes depending on local availability and Ostrich farm proximity.
Q: Can we use this kind of stirrups, instead of the common stirrups?
A: The stirrup configuration appears acceptable. Please note that the method used to connect the pieces of reinforcement is limited by Rule 2d.
Questions submitted for the 2012 EPD Competition
Q: The rules say that every 360 degrees counts as one of our 15 stirrups. Does that pertain solely to a helically shaped member or would we be allowed to spin the wire without “wrapping” it into a spiral or circle, but merely twisting it? The wire itself would not take any other shape other than a straight line once we are done doing this.
A: The 360 degree turn refers to helical-shaped or spiral reinforcing. Spinning the wire reinforcement would be acceptable, as long as the final diameter does not exceed the maximum permissible diameter.
Q: Can you define "small gauge tie wire"?
A: Please refer to Section 4 of the rules and the associated sketch. There are no minimum requirements for the width stated, except for the 100 mm long section noted in Rule 4.d.
Q: My question is regarding Rule #4 Part (a). My teammates and I are not sure how to interpret the dimensions given. It makes sense that every EPD must span 400 mm ± 5 mm, but I was wondering about the 200 mm ± dimension. I understand it cannot be any bigger than that, but if we designed ours to be 100 mm wide, does that fit this guideline? (What I am unsure about is if at some point our EPD MUST hit 200 mm ± 5 mm and 400 mm ± 5 mm or if that is just the maximum, as the EPD must fit into the base plate of those dimensions.
A: These are maximum dimensions to account for the hole in the base plate. There is no minimum width stated in the rules, although the EPD will have to be stable to protect the egg.
Q: In the rules, Number 2, letter c states that we can't use flat-plate-type embedments or covering. Can I use Styrofoam in columns?
A: Materials are limited to those specified in the EPD Rules, Section 2. Any materials not listed but used in the EPD may result in disqualification. Final decisions will be at the discretion of the judges on site.
Q: Does the EPD need to be the 200 mm (± 5 mm) thick or can it be the same width as the top pad where the load is to be dropped (50 mm)?
A: Please refer to Section 4 of the rules and the associated sketch. There are no minimum requirements for width stated, except for the 100 mm long section noted in Rule 4.d.
Q: We saw the rules for mixture of concrete in Section 2a; is Ductal an approved concrete?
A: The committee is not immediately familiar with Ductal concrete, but in accordance with Rule 2b, fiber reinforcement would not be permitted.
Q: Can I use lap reinforcement to achieve the desired length? Will the lap be considered a type of bundling? Will the lap affect the number of bars in a cross section?
A: As the rules state, no more than eight longitudinal bars may pass through any cross section. This would include lapped reinforcing. Determination of bundling will be at the discretion of the judges, but any reinforcing grouped together will likely be considered bundling.
Q: What is the ACI definition of "stirrup" that will be used in judging?
A: Per Rule 2b, a stirrup is reinforcement typically bent into a u-shape or box-shape and placed perpendicular to or at an angle to the longitudinal reinforcement, causing it to be used as shear reinforcement running in the transverse direction to the cross section of the EPD. Numerous configurations would be possible.
Q: Is the use of braided reinforcements permitted?
A: Braiding of longitudinal bars is allowed per the current rules; however, the stirrups shall not be braided, as that is considered a form of bundling, which is not allowed per Rule 2b.
Q: It states that no more than 15 stirrups may be used in the EPD. Does this mean that there can only be 15 stirrups total including those used in the columns of the EPD?
A: Yes, per Rule 2b, stirrups are transverse reinforcement, which would include reinforcement placed in the transverse direction in the columns (legs) and no more than 15 total stirrups are allowed.
Q: Would a spiral reinforcement setup for the columns be acceptable?
A: Yes, spiral stirrup reinforcement is permitted. Each full 360-degree turn (or step) is considered one stirrup. For example, if in one leg of the EPD a team has five steps of spiral stirrup reinforcement, 10 stirrups would be left for the rest of the EPD.
Q: Do the reinforcements need to be on a major axis? Can it be curved or skewed?
A: Reinforcements are classified as longitudinal and stirrups (transverse) per Rule 2b. Many different reinforcement arrangements are possible so an exact answer can't be given; however, reinforcement arrangement, which contains curved or skewed reinforcement, are possible. When determining the classification of a particular pile of reinforcement (longitudinal versus stirrup), the judges will consider what function that piece of reinforcement is primarily servicing (that is, flexural resistance, shear resistance, and so on.).
Q: Does the concrete have to have aggregate material or is cement paste sufficient? Additionally, if aggregate is required, is coarse aggregate required or will fine aggregate suffice?
A: Aggregates are not required to be used. Rule 2d covers the aggregate permitted to be used; either fine and/or coarse (up to 3/8" size) aggregate may be used.
Can we use the figure above for the stirrups of the beam?
A: It appears that you are planning on your stirrup configuration to be a closed stirrup with two crossties, which would be acceptable. However, keep in mind that the method to connect the various pieces of reinforcement making up the stirrup (main stirrup and two crossties) is limited by Rule 2b.
Q:May we use Brazilian cement?
A: Per Rule 2a, the cementitious binder shall meet the ASTM standards listed. It is certainly possible that the Brazilian cement you are planning to use will meet these requirements (a lot of international cements do); however, you should obtain a letter from your cement supplier verifying this.
Can the loop configuration adopted for the anchoring of the reinforcement longitudinal beam be used?
A: It appears that you are planning to provide a hooked end to your longitudinal reinforcement, which would be acceptable.
Q: May we use other forms of mesh? The rules state the restrictions of wire mesh but not a plastic- or carbon-based material.
A: Mesh is not permitted. "Wire mesh" does not imply what the material is (that is, steel versus fiber reinforced polymer). Also note, the mesh would likely violate the maximum amount of reinforcement for both stirrups and longitudinal reinforcement, as well as the maximum diameter.
Q: How many specimens may we enter in the competition?
A: Per Rule 1f, each school may enter up to two items. Each team submits one EPD for testing.
Q: Does the eight bar/wire limit apply to the maximum amount that can run perpendicular to the plane of the cross section provided in the rules (in and out of the cage)? Can you explain the difference between the direction of the stirrups and longitudinal reinforcement?
A: As indicated in Rule 2b, the eight bar/wire limit applies to the longitudinal reinforcement that generally runs parallel to the length of the member—that is, the length of a beam or the height of a column—but this does not necessarily mean that they are exactly parallel (for example, draped reinforced in a beam). The stirrups are generally normally oriented or at an acute angle to the longitudinal reinforcement and are generally perpendicular to the length of the section but may not be exactly perpendicular (for example, inclined stirrups in a beam). As many different configurations of reinforcement are possible, it is impossible to describe every scenario. However, ACI does define these terms on their Web site under "ACI Concrete Terminology."
Q: Since the rules state that "fibers are not permitted" and that "any type of aggregate may be used," does this mean that aggregates cannot be composed of fibrous materials such as wood or bamboo? Can you explain exactly what "fiber" means?
A: As previously mentioned, ACI defines the term "fiber" in the "ACI Concrete Terminology" section on their Web site. Fibers that may be desirable to use as reinforcement (part of ACI's definition) are not allowed in the EPD. Note that ACI's definition of aggregates indicates that they are granular materials; granular materials are not long and slender like fibers. Fibrous aggregates such as wood or bamboo that will pass through the specified sieve size and that do not meet the definition of fibers—that is, slender and elongated, generally with lengths of more than 100 times their diameter—are acceptable. Teams that attempt to use fibrous aggregates must not allow the aggregates to fibrillate—that is, break down from a granular material and form fibers—at any time. The aggregates also must not be considered a flat plate type of embedment per Rule 2c.
Q: If an air frame has two legs, one at each side of the frame, can we only use four longitudinal bars on each leg or could each leg have eight longitudinal bars?
A: Rule 2b refers to the whole cross section of that portion of the EPD (that is, cutting a plane through both legs in this case). A maximum of eight longitudinal bars may be used per side in the plane cut through the whole specimen. If a team has two legs on a side and desires equal reinforcement in each leg, they would have a maximum of four longitudinal bars in each leg at any given point within the legs.