Hip/Valley Roof Beam Module Walk-Thru

To begin sizing a hip or valley roof beam in StruCalc first begin by opening the roof beam module. This is done by one of three ways: the first way to open the roof beam module is by going to the top tool bar and clicking Design Modules, then moving your mouse down to Beam Design, and finally moving your mouse over and clicking on Roof Beam (see Figure 1).

The second way to open the roof beam module would be simply clicking on the Roof Beambutton located on the bottom tool bar of StruCalc (see Figure 2).

The third and final way to open the roof beam module would be by holding down the “Shift” key on your keyboard and hitting the “F3” key on your keyboard.

Once the module is open there is some basic information that is needed before a suitable beam size can be determined. A fraction of this information is entered in the module portion of the program (see Figure 3) and another portion is entered on the left hand of the screen (see Figure 4 and Figure 5), under what is called the Navigation Tool Bar. In any module of StruCalc the most efficient way to do the design is to work from the top of the screen down. However, to size a hip or valley beam in StruCalc the hip/valley portion of the module needs to be initialized. The hip/valley beam part of the module is initialized by checking the Hip/Valley Beam box at the bottom of the module. To now begin the discussion on sizing a hip or valley beam let’s first start with the information to be entered in the module:

Starting at the top, the first piece of information to enter is simply the name of this member. By default, StruCalc will give each member a name, and in the roof beam module it is “Roof Beam 1.”

Next, the program needs the span length of the beam to be designed. It should be noted that if the Side 1 or Side 2 lengths are changed the span length will be changed. This is because the geometry of the roof assembly: the beam length, roof pitch, and rafter length are all dependent on one another.

After a span length of the beam is entered StruCalc will need the unbraced length for the top of the beam. This is typically the spacing of the rafters or trusses.

If an intermediate support is located in the span of the hip beam the unbraced length of the bottom of the beam will need to be specified. This is conservatively taken to be longer of the two lengths of distance from the end supports to the intermediate support.

Also at the top of the module is the option to choose between Snow and Non-Snow. This is indicating the type of live load that will be on the rafters, and that the rafters will support. If the designer is unsure of this value, he/she should contact the building department governing the jurisdiction where the structure will be built.

Continuing down, the next information to be entered is the roof live load and roof dead load. The roof live load was discussed earlier, and is either the design snow load, or the minimum roof live load. StruCalcdefaults the roof dead load to 15 pounds per square foot, which is a pretty common industry standard value.

Figure 1

Figure 2

Figure 3

Next, is a box to enter the load per foot of for a wall that would run the length of the beam, and that the beam would support. Typical design values for the weight of wood framed wall would be 10 pounds per foot, per foot of height of wall (i.e. an eight foot wall would generate an 80 lbs/ft load).

Now, the designer can focus on the information that is specific to a hip or valley beam.o The first box in this section is one indicating whether or not the rafter length and roof pitch will

be the same on both sides of the hip or valley beam. If this is the case the user should check the box entitled Equal Sides.

o There is also an option to specify between half or full tributary width for both side one and side two of the beam.

o Next, the program needs to know the roof pitch of the rafters to be designed on both side one and side two of the beam. This should be indicated on whatever plans are being used for the design.

o If there is an intermediate support between the end supports of the beam there is a box to check. When this box is checked StruCalc then asks where the support is located in relation to the left end of the beam.

o Also, when the intermediate support box is checked an option appears asking if the end at location ‘A’ is cantilevered. Boxes also appear for a point load to be entered on the cantilevered end if applicable.

Now that the information in the module has been entered we can focus on the left hand side of the screen (the Navigation Tool Bar). The first group of information to be specified is under the Material Codes section and is the Building Code, NDS, and Steel Design Specification (see Figure 4).

The next group of information to be specified is also location in the Navigation Tool Bar. This information is under the Material Properties section (see Figure 5). A description of this information is as follows, again working from the top of the screen down:

The first box to be checked after the material type, species, and grade drop down boxes (for solid sawn) is the option for round members. This would allow the user to design a roof beam with a round log.

When solid sawn or glulams is selected as the material of choice, there is a button to indicate whether the beam will be dry or wet.

Next, when solid sawn beams are being designed, there is a check box for Flat Use. Continuing down, when solid sawn or glulam beams are designed the next box to

check says Apply the Incising Factor. A box to check that is applicable to all materials is the one that says Check

Unbalanced Loads. This will only be applicable in the uniformly loaded roof beam module when designing a hip or valley beam with an intermediate support. This should always be checked.

When solid sawn, glulam, or structural composite beams are being designed there is an option to enter a notch depth if applicable.

When steel or tube steel beams are being designed a drop down box for grade is shown. Based on the steel beam shape StruCalc will select the recommended grade as specified by the AISC steel manual.

When steel or tube steel rafters are being designed there is a drop down box for Cb. This value is always conservatively taken to be 1.0.

Figure 4

Figure 5

The deflection criterion also needs to be defined. By default StruCalc will put the correct numbers in these boxes.

Finally, the last drop down box for wood members is the duration factor. The roof beam module should only have two different duration factors: 1.15 when the live load is snow loading or 1.25 when the live load is non-snow.

Once this basic information has been entered structural members can be determined. There are two ways members can be sized: the first is to utilize the AutoSize function of StruCalc, and the second is to have a size in mind, and check the adequacy. Both methods will be gone through in detail in the following section.

The AutoSize function of StruCalc is the easiest way to determine a member size for a given loading. To use the AutoSize function:

First, click the AutoSize button on the left of the StruCalc screen (see Figure 6)A material and species (or manufacturer, for structural composite members) will have to be selected before the AutoSize feature can run.Then, select a grade (for wood member) or a depth (for steel members). Note, that multiple grades or depths can be selected by holding down the “Ctrl” key and clicking the grades or depths in the list.After the grades or depths are selected click on the Run button (see Figure 7) to run the AutoSize feature.Once the AutoSize feature has been run, it will come up with a solution list based on the grades or depths the user has selected and show the percent adequate of each solution. From this list the user should be able to find a solution they are comfortable with. The user should click the solution they desire, then click the Select & Return button (see Figure 8) and the program will return to the design screen and show the adequacy in large green letters along with the controlling factor (see Figure 9).

The next way to determine a member size would be to simply estimate a size, and clickthe Calculate button (see Figure 10) located on the bottom tool bar. This will perform

all the calculations necessary to determine a member’s adequacy and return a block of information that would look like Figure 9 if the member is adequate. If the member is inadequate the green circle would be red, and instead of a check mark, there will be an x. If the member is inadequate, the member size should be increased. Once a new member has been selected click the Calculate button again, and start the process over.

At this point the solution has been generated, and decided on, and all that is left to do is save the analysis. There are three different ways to save an analysis: the first way to save an analysis is by going to the top tool bar and clicking File, then moving your mouse down and clicking on Save Roof Rafter 1 (see Figure 11).

The second way to save an analysis is to click on the Save button (see Figure 12) located on the bottom tool bar.

The third and final way to save and analysis would be by holding down the “Ctrl” key on your keyboard and hitting the “S” key on your keyboard.

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12