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The following is a summary giving a brief description of the important new features for WoodWorks Shearwalls USA, version 10. Refer to the rest of the subtopics for full explanations of these features and a full list of changes .
Version 10 of Shearwalls updates several design codes and standards used in the program. The details of the associated changes to the program appear throughout the rest of this list of changes, this section just identifies the design standards changed.
The implementation in Shearwalls the IBC has been updated from the 2009 edition to 2012, the ASCE 7 from 2005 to 2010, and the NDS from 2005 to 2012 as follows:
The references to design standards have been updated in messages, notes, table legends, the log file and the help file, , especially for ASCE wind loads, which were completely re-organised and re-numbered for ASCE 7-10.
With ASCE 2010, the terminology “Directional” is used to refer to what used to be called “All Heights” loads (Chapter 27), and the term “Envelope” is used to refer to what was “Low-rise”. The old terminology is still used in the captions to the Figures giving the particulars of these methods. This change has been implemented in the program.
There is no longer an importance factor I for wind design. Instead different maps are provided for different Risk Categories (ASCE 26.5) instead of a single map with importance factors to be applied for each risk category. Therefore, the importance factor has been removed from Shearwalls for wind design.
The program now generates both Case 1 and Case 2 loads from Figure 27.4-8 simultaneously, and uses the heaviest loading from each of these cases and the minimum load case as the design shearline force on each line. Previously, if you had to generate these loads in a separate design run and manually compare the resulting designs to determine the critical case.
The program has implemented the change in intensity for minimum wind pressures in ASCE 7-10, minimum wind loads from ASCE 27.1.5 and 28.4.4. as a separate, simultaneous load case, and over-rides of the intensity of minimum pressures for local design codes.
ASCE 7 has restored the model of low-rise loading in figure 28.4-1 to have the same nomenclature and set of load cases that it did with ASCE 7-98 and before, and that was implemented in the versions of Shearwalls before 2004c , released in July, 2006. Version 10 also restores these load cases and nomenclature.
The program now allows you to optionally implement ASCE 7-10 figure C28.4-2 for wind loads on hipped roofs..
ASCE 7 Commentary C27.4.6 states that the 15% eccentricity and 75% for All Heights Case 2 loads may not cover all cases, and said for certain buildings, 5% eccentricity at full loading is more appropriate. Therefore, we now allow you to control the eccentricity and percent loading to be used, with the default being 15% and 75%.
The program now implements the Exception to 27.4.6, referring to Appendix D 1.1, which says that buildings two stories or less do not require Case 2 loads (75% loading plus 15% moment).
ASCE Commentary C27.3.2 indicates that the 0.00256 constant used in the calculation of wind pressures in Eqn. 27.3-1 corresponds to average air pressure at sea level and if sufficient weather data are available a value based on actual air pressure can be used. Therefore the program now allows you to adjust this value.
The program implements the 0.6 ASD load combination factor for C&C loads, windward C&C pressures for display, and separate C&C loads on each wall line when roof heights differ.
The program also implements a number of small improvements and bug fixes relating to wind load generation input and output.
Occupancy has been renamed “Risk Category” and the symbol for Importance factor changed from I to Ie
The program now calculates the total diaphragm design force Fpx from equation 12.10-1 in 12.10.1.1 on each floor in each direction. This force is output to aid you in manually doing diaphragm design calculations (Shearwalls does not model or design diaphragms), and is the force used for the 25% increase in drag strut forces required by 12.3.3.4 for irregular structures.
The program now implements ASCE 7 12.8.4.3, the amplification of accidental torsional moment, for Seismic Design Categories C-F.
ASCE 12.8.6 indicates that he design story drift is to be computed at the center of mass, except for structures with torsional irregularities which must use the largest story drift at the edges of the structure/ ASCE 12.3.1.1 indicates that all shearlines must satisfy story drift limitations for the building to be modelled with flexible diaphragms. These provisions have been implemented in the Shearwalls
The program now shows calculates and displays the out-of-plane forces for structural walls from ASCE 7 12.11.
You are now able to specify ρ instead of having the program calculate it, and the factor has been removed from the body of the Seismic Information table to the notes below.
The program also implements a number of small improvements and bug fixes relating to seismic load generation input and output, including the display and update of the Seismic Design Category in the Site Information dialog.
The program implements the change in ASCE 7 of the ASD wind factor to 0.6 from 1.0; it retains the 1.0 wind load combination factor for deflection, which is now the strength-level factor in ASCE 7; it no longer allows input of different load combination factors than those in ASCE 7, and it shows in the output the load factors used for deflection design.
ASCE-7 10 has provided less restrictive conditions for which flexible diaphragm assumptions can be made for seismic design, such that any light frame construction without concrete topping on the diaphragm can be idealised as flexible, so long as each shearline complies with storey drift limitations in 12.2-1 (which are ordinarily required to be met only at the centre of mass of the structure). For this reason, and in order to speed up processing time for complex structures, Shearwalls now allows you to choose whether to design for rigid diaphragms, flexible diaphragms, or both.
Previously, the program did not include the inherent torsions due to the moment between the center of wind loading and center of rigidity, as this was not explicitly specified in torsional load cases that are now in ASCE Fig. 27.4-8 for the All Heights method. However Commentary C27.4.6 says that the torsional load to be added for Case 2 is due to non-uniform wind loading, not the eccentricities in the loading due to the geometry of the structure. Discussion with ASCE confirmed that for rigid diaphragms, it is the intention to include inherent torsion due to building geometry to both Case 1 and Case 2.
When you selected low rise wind loads, the seismic rigid diaphragm torsions were set to zero in the rigid diaphragm distribution method, so there was no additional torsional component to seismic shearline forces for rigid diaphragms, and the direct forces only were used. When the all heights wind load procedure was selected, the seismic torsions were correct. This has been corrected and seismic rigid diaphragm torsions are always calculated.
ASCE 7 Commentary C 27.4.6 says that the torsional load cases are due to non-uniform wind loading, which is applicable to flexible diaphragm buildings as well as rigid diaphragms. Discussions with ASCE confirmed that the intention was to apply Case 2 loading to flexible diaphragm design. Sizer now includes Case 2 loads and torsional moments for flexible diaphragm design.
The program now allows you to choose whether the longer moment arm to the sloping roof, or the moment arm to the ceiling, is used for upper level hold-down calculations at the gable end. We also fixed a problem with the calculation of the longer moment arm when there were openings beneath a gable end.
Significant new information and reformatting of existing information for readability, as well as corrections to inaccuracies, have been made in the torsional analysis section of the log file.
The program also implements a number of small improvements and bug fixes relating to the output of load and force distribution.
If a wall failed design for the design case ( wind, seismic, rigid, flexible) shown on the screen, then the failing wall appears in red. The colour for a selected wall, which used to be red, is now orange.
A note at the bottom of the screen indicates that orange is for selected walls and red for failing walls. It also indicates the design case being shown on the screen.
The program now allows input of 19.2” stud spacing, corresponding to 1/5th of the length of a standard sheet of plywood, and the associated unblocked factor from SDPWS Table 4.3.3.2.
Previously, the program allowed input only of Windows Metafile (.wmf) or Enhanced Metafile (.emf) file formats for CAD drawings to use as a template to draw your structure. Now, the program allows you to input bitmap (bmp) and portable document format (pdf) files. The program converts the pdf to a bitmap before drawing it.
The program allows you to extend your walls upwards in stages, that is, extend walls up through a more limited number of levels than to the top of the building. However, in order to maintain a closed envelope, you must always extend the walls through at least one level and cannot build a level from scratch.
A Copy button has been added to Standard Wall input to make the copying of existing standard walls easier.
As it was difficult to see openings on imported CAD drawings as the solid shearwalls in plan view obscured them, the drawing for the openings action when CAD drawing is showing has been modified to allow you to see openings
Previously, and opening could only be selected via a drop list in the Opening Input form. Now in the Openings action of Plan View, if you select anywhere within the thickness of the wall over the extent of any of the openings, then the opening selected is the one available for editing in the input form.
Shearwalls now allows you to transfer the design results from a successful design back to the input fields, replacing unknown values on those fields. This allows you to experiment with and tweak your design, for example to use fewer different types of materials at the expense of optimal strength in some areas.
A button has been added to the main program tool bar to invoke the log file, and to toggle the log file viewer on and off. The log file button has been removed from the toolbars attached to the windows for Plan, Results, and Elevation views.
A number of other small improvements were made to the design results tables and their legends.