Asce 7-10 Free Download
Luz Ignasiak
The webinars offered by ASCE are the easiest ones for me to present groups. I appreciate how consistently ASCE organizes its webinars. - Dana M. Hardy, Executive Secretary City of Oklahoma Utilities Administration
Since the first editions (2000) of the International Building Code (IBC) and the International Residential Code (IRC), ASCE 7 has been referenced for the design of buildings for wind loads. The 2015 editions of the IBC and IRC reference ASCE 7-10 for the design of wind loads. Due to the significant number of organizational and technical changes to ASCE 7-10, many transitional changes to the IBC and IRC were made. This webinar will address the significant changes in the wind load provisions of the 2010 Edition of ASCE 7-10 that impact the wind provisions in the 2015 IBC and 2015 IRC. The basic wind speed maps have been updated to reflect strength design-level wind speeds while also incorporating newly available data. The methodology for incorporating the new wind speed maps into the IBC and IRC, and how these new maps affect wind speed triggers will also be addressed. This webinar will also address the changes in the IBC and the IRC necessary for correlation with wind load design provisions of ASCE 7-10.
The new wind provisions in ASCE 7-10 have been incorporated into the 2015 IBC and the 2015 IRC in different ways. You will gain an understanding of the key changes to ASCE 7 that impact provisions in the 2015 IBC and the 2015 IRC, and the required changes in the IBC and IRC for correlation with the new wind provisions in ASCE 7-10.
ASCE 7-16 contains significant changes from ASCE 7-10 in the areas of seismic design, wind design, snow design, and more. A brand new chapter on design against tsunami loads has been added. Several of the seismic chapters have been extensively rewritten. Since ASCE 7 eventually becomes law through adoption by the International Building Code (IBC) and then through adoption of the IBC by legal building codes of local jurisdictions, a practicing engineer has no choice but to keep up with these changes. The changes are also of interest to the code enforcement community, academics, advanced-level students, and others.
This seminar discusses all significant changes between the 2010 and the 2016 editions of the ASCE 7 standard, following a chapter-by-chapter sequence. Each change is explained, the background to it is given to the extent practicable, and its impact is also discussed, when that can be assessed. The emphasis is on what a practicing engineer needs to implement the changes in their design, with confidence and full understanding.
ASCE 7-16 is scheduled to be released in early January 2017. Barring unforeseen circumstances, it will be the referenced standard for design loads and seismic design provisions in the 2018 IBC. ASCE 7-16 will thus acquire the force of law within a city, county, or state whenever that legal entity adopts the 2018 IBC as the basis of its building code. Thus practicing engineers and code enforcement personnel have no choice but to keep up with changes in the ASCE 7 standard.
Practicing structural engineers, code enforcement personnel in building departments, structural engineers in government agencies, university faculty in structural engineering, and advanced-level university students studying structural engineering.
The effect of snow loads on a structure can have dire implications if not taken into account during the design period. Procedures and guidelines set out by ASCE in ASCE 7-10 give the structural engineer direction on what these loads are depending on your location in the United States, and how to apply them.
SkyCiv Structural 3D (S3D) gives users the power to load their structures easily and efficiently to meet the design requirements. In this section, we will outline how to calculate snow loads and apply them to your structure, as guided by ASCE 7-10.
Before we can apply any snow loads to our structure, we need to know the ground snow load at our location, which can be found using Figure 7.1 from ASCE 7-10. In our case, the ground snow load is 30 psf.
The exposure factor is determined using Table 7-2 in ASCE 7-10. In our case, the exposure/terrain category for the majority of Madison, Wisconsin is Category B; we will assume that the roof is partially exposed. Therefore, our exposure factor is 0.9.
The importance factor is something that is not just exclusive to snow load calculations, there are also ice and seismic importance factors as well. To find the snow importance factor for your structure, first find the Risk Category from Table 1.5-1. In our case, we will assume that the Risk Category is Risk Category II, the most common. Next, go to Table 1.5-2 to find the Importance Factor. For this exercise, the snow importance factor is 1.00.
In our case, this is our unfactored, balanced design snow load that will be applied to the structure. The balanced snow load is applied everywhere where the roof structure is located. This includes overhangs and multiple roof levels.
The roof slope factor is dependent on various roof properties including temperature, shape and material. The roof slope factor can be determined through Sections 7.4.1 through 7.4.4 of ASCE 7-10 and can be known as:
After you obtain the roof slope factor from those sections in ASCE 7-10, the balanced design snow load for the sloped roof can easily be calculated using equation 7.4-1. The balanced snow load is applied everywhere where the roof structure is located. This includes overhangs and multiple roof levels.
Partial loading must be applied for continuous beam systems in accordance with Section 7.5-1. Three separate cases must be applied, these cases are illustrated in Figure 7-4. In some cases, the greatest effects on a member are found where only half the balanced snow load is applied. See Section 7.5 for more information.
Due to the variability of shapes and geometries of roofs, and their interaction with differing wind directions, unbalanced snow loads can differ quite a bit. Different unbalanced loading provisions are present for hip and gable roofs, curved roofs, sawtooth roofs, and dome roofs.
Roof designs usually present multitudes of roof elevations and rarely offer one single roof height. Because of this, there are roof areas higher and lower than each other and are subject to snow drifts. Snow can either blown from the low side of the roof towards the high side, or is blown off the higher area of the roof onto the lower projected side. The amount of additional snow load, or surcharge, depends on the difference in height of the two adjacent roofs and the lengths of roof perpendicular to the drop in height. See Section 7.7 and 7.8 for more information.
The significance of these changes is the increase in pressures that must be resisted by roof construction elements subject to component and cladding wind loads including but not limited to roof framing and connections, sheathing, and attachment of sheathing to framing. To resist these increased pressures, it is expected that roof designs will incorporate changes such as more fasteners, larger fasteners, closer spacing of fasteners, thicker sheathing, increased framing member size, more closely spaced roof framing, or a change in attachment method (e.g., change smooth shank nails to ring shank nails or screws). An example of these wind pressure increases created by the increase in roof pressure coefficients is illustrated in Table 1. This Table compares results between ASCE 7-10 and ASCE 7-16 based on 140 mph wind speeds in Exposure C using the smallest EWA at 15-foot mean roof height in Zone 2. Pressure increases vary by zone and roof slope. In some cases not shown in Table 1, such as for Zone 1, the revised coefficients produce an approximate doubling of roof pressures.
Table 2 illustrates the Zone 2 (20- to 27-degree slope) C&C pressures for ASCE 7-10 compared to the pressures developed in accordance with ASCE 7-16. The comparison is for 10 different cities in the US with the modifiers for Exposure B taken at 15 feet above grade, location elevation factor, smallest applicable EWA, and reduced wind speeds from new maps applied from ASCE 7-16 as appropriate.
As illustrated in Table 2, the design wind pressures can be reduced depending on location elevation, wind speed at the site location, exposure and height above grade, and roof shape. Wind pressures have increased in the hurricane-prone regions where Exposure C is prevalent and wind speeds are greater. The added pressure zones and EWA changes have complicated the application of these changes for the user.
Figures 2 and 3 illustrate the changes in the number of zones as well as the increases in the roof zone coefficients from ASCE 7-10 to 7-16 for gable roofs. Designers are encouraged to carefully study the impacts these changes have on their own designs or in their standard design practices. The reduced pressures for hip roofs in ASCE 7-16 are finally able to be demonstrated in Table 2; the design premise for hip roofs has always suggested this roof shape has lower wind pressures, but the C&C tables used for design did not support that premise until this new ASCE 7-16 edition. There is interest at the ASCE 7 Wind Load Task Committee in studying ways to make these changes simpler and reduce possible confusion in the application of C&C provisions for the ASCE 7-22 cycle.
ASCE 7-16 is referenced in the 2018 International Building Code (IBC) for wind loads. In the 2018 International Residential Code (IRC), ASCE 7-16 is referenced as one of several options where wind design is required in accordance with IRC. Other permitted options based on ASCE 7-16 include the 2018 IBC and the 2018 Wood Frame Construction Manual (WFCM). Other permissible wind design options which do not reflect updated wind loads in accordance with ASCE 7-16 include ICC-600 and AISI S230.
In tools > job preferences Robot 2015 provides load combinations from ASCE 7-2010 but only snow/wind loads from ASCE 7-2005. Does Robot 2016 or 2017 allow for snow/wind loads from ASCE 7-2010? Is this not much of a concern because most users apply snow/wind loads to 3D structures where they have to be entered manually?
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