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ASCE 7 2005 PDF

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This document contains errata to ASCE and is periodically updated and posted on b shall be used to determine the roof slope factor Cs. For cold roofs. Minimum Design Loads for Buildings and Other Structures, ASCE/SEI , Softcover, pages, ISBN: , Stock #, List Price $ ASCE/SEI Minimum Design Loads for ASCE/EWRI Standard Practice for the Design ASCE/SEI Design of Steel Transmission Pole.


Asce 7 2005 Pdf

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ASCE. ASCE STANDARD. ASCEISEI Including Supplement No. 1 ASCE and American Society of Civil Engineers-Registered in U.S. Patent and. American Society of Civil Elilgineers. SEI/ASCE Second Edition. Minimum Design Loads for. Buildings and Other Structures. Revision of ASCE pdf. ASCE Minimum Design Loads for buildings and other Structures. Pages ASCE STANDARD ASCEISEI Including Supplement No.

Skip to main content. Log In Sign Up. Kishor Mehta. Mehta, Ph. William L. Coulbourne, P. Wind loads:

Roof distances are from windward edge. The structural designer will need to make a judgment for each building designed. Design Pressures for Components and Cladding Chapter 30, part 1, of the Standard is used to obtain the design pressures for components and cladding.

GCp values are obtained using equations in chapter 2 of this guide. MWFRS Load Figure G shows design pressure on an end wall with wind parallel to the ridge with positive internal pressure consistent with high uplift on the purlin. Assuming that the end wall is supported at the bottom and at the roof line, the effective axial load on an end bay purlin can be determined. Note that many metal building manufacturers support the top of the wall panels with the eave strut purlin see bottom of Fig.

For this case, the eave purlin also serves as a girt, and the negative wall pressures of Zones 5 and 4 would occur for the same wind direction as the maximum negative uplift pressures on the purlin refer to Zones 3 and 2. Comment The pressures determined are limit state design pressures for strength design. Section 2. If allowable stress design is to be used, the load factor for wind load is 0.

For this purpose, the building used has the same dimensions as the building in Section 5. The building is shown in Fig. The building data are as in Table G, except that the openings in the framing are uniformly distributed. G Combined design loads on interior strut purlin.

All pressures for a given zone are assumed to be uniformly distributed with respect to height above ground. For each of these patterns, both positive and negative internal pressures must be considered, resulting in a total of 16 separate loading conditions. However, if the build- ing is symmetrical, the number of separate loading conditions will be reduced to eight two directions of MWFRS being designed for normal load and tor- sional load cases, or a total of four load cases, plus one windward corner, and two internal pressures.

The load patterns are applied to each building corner in turn as the reference corner. Design Wind Pressure Design wind pressures in the transverse and longitudinal directions are shown in Tables G and G Thus, the distance from the edge of the roof is the smaller of: The pressures are assumed to be uniformly The load combinations illustrated in Figs.

G in Section 5. Other surfaces will have the full design pressures. Figures G through G show design pressure cases for one refer- ence corner; these cases are to be considered for each corner.

G 8. G 3. The pressures are 7. G 4. The pressures are G 2. G 0. G, and data are shown in Table G The example in Section 6. The same building is illustrated in Section 6. It is not considered an essential facility. Build- ing Category II is appropriate; see Table 1. The wind speed map to be used with this category of building is in Fig. Basic wind speed for Corpus Christi, Texas, is mph interpolating between isotachs on Fig.

If the detailed procedure for a rigid structure is used Section Detailed calculations for G value are illustrated in Section 4.

The glazing protection requirements are given in Section The example building has debris-resistant glazing, and other openings are such that it does not qualify for a partially enclosed or an open building.

This value of smaller uplift pressures on the roof can become critical when wind load is combined with roof live load or snow load; load combinations are given in Sec- tions 2. The internal pressures shown are to be added to the external pressures as appropriate. The internal pressures of the same sign act on all surfaces; thus, they cancel out for total horizontal shear. Load Case 1 has been considered as explained. Internal pressures cancel, so they are not shown. Pressure for glazing and mullions can be determined similarly with the known effective wind area.

Roof Joist Pressures Roof joists span 30 ft and are spaced 5 ft apart. The joist can be in Zone 1 interior of roof or Zone 2 eave area. Zone 3 roof corner area acts only on a part of the joist.

Width of Zones 2 and 3 Fig. Design Forces on Rooftop Equipment Design wind forces are determined from the provisions of Section Data for the building are shown in Table G It is a simple diaphragm building. The mean roof height h is less than 60 ft and does not exceed the least horizontal dimension. It should be designed to conform to the wind-borne debris provisions of Section It has a regular shape. There is no expansion joint.

The building is exempted from torsional load cases as indicated in Note 5 of Fig. Wind speed map in Fig. Note that wind pressure values given in Figs. Topographic Factor, Kzt From Section The wall pressure is the combined windward and leeward wall pressures internal pressure cancels. Linear interpolation is permitted in Fig.

Linear interpolation is required for wind speed of mph and effective wind area of 75 ft2. Values of ps30 are obtained from Fig. The load patterns shown in Fig. G shall be applied to each corner of the building in turn as the reference corner; see Note 2 of Fig. From Fig. The building data are listed in Table G Therefore, chap- ter 27, part 1, of the Analytical Procedure, is used see Section For components and cladding, chapter 30, part 1, for low-rise buildings is used. Use Category II see Table 1.

Since the building is sited within 1 mi of the coastal water, it is con- sidered in a wind-borne debris region. It has glazing that must be impact resistant occupying 50 percent of a wall that receives positive pressure. For the overhang, Section The Standard does not address the lee- ward overhang for the case of wind directed toward a ft wall and perpen- dicular to roof slope parallel to ridge. The building is sited in a hurricane prone region less than 1 mi from the coastal mean high-water level.

The basic wind speed is mph, and the glazing must be designed to resist wind-borne debris impact or some other method of protecting the glazing must be installed, such as shutters. For brevity, loading for this value is not shown here. The Standard does not address bottom surface pres- sures for leeward overhang.

Figures G and G illustrate the external, internal, and combined pressure for wind directed normal to the ft wall. Figures G and G illustrate combined pressure for wind directed normal to the ft wall and perpendicular to slope parallel to ridge line , respectively see Table G Case 1 includes the loadings shown in Fig. G through Fig. The exception in Section G a Since the CMU walls are supported at the top and bottom, the effective wind area will depend on the span length. For z, distance along roof is from leading windward edge.

For the roof, pressure on the overhang is only external pressure contribution on underside is conservatively neglected. Note that the zones for roof overhangs in Fig. Similar to the determination of design pressures for walls, the critical design pressures for roofs are the algebraic sum of the external and internal Table G Roof Design Pressures by Zone psf Zones 1, 2, and 3 Zone 1 Zone 2 Zone 3 Component Positive Negative Negative Negative Joist Zones for overhang are in accordance with Fig.

The panels are designed for the pressures indicated. Roof joist design pressures need careful interpretation. The high pres- sures in corner or eave areas do not occur simultaneously at both ends.

Two loading cases: G based on the following zones: Zone 1 for roof and Zones 1 and 2 for overhang For simplicity, only one zone is used for overhang pressures in Fig.

G Wind for Loading 3 Design pressures Wind for 80 ft Loading 1 for typical joists and 16 ft 16 ft pressure zones for Zone 3 for roof Zone 2 8 ft roof components and for roof cladding joist 2 joist 1 Zone 2 for roof Zone 2 4 ft wide 32 ft Zone 1 Zone 2 for roof for rooof for overhang 4 ft wide Zone 3 for overhang 4 ft x 4 ft 7 ft Zone 2 Zone 1 Wind for for overhang for overhang Loading 2 4 ft wide 3 ft wide Wind for Loading 4 Loading on Joist 1 Loading on Joist 2 Various views of the house are provided in Fig.

The physical data are presented in Table G Wind speed map associated with this risk category is Fig. Glazing is uniformly distributed. The wall surfaces are numbered 1 through 6; roof surfaces are 7 through 11; porch roof surface is Wind Direction A See Fig. G a 2 ft Overhang Roof pressures calculation Surface 7: Same pressures as surface 8 Surface Same as surface 8 without internal pressure Overhang pressures From Section Internal pressure is of the same sign on all applicable surfaces.

Wind Direction B Wall pressures Surface 1: Even though technically this surface is a side wall, it is likely to see the same pressure as surface 6. Surface 6: Bold type indicates value gained by interpolation. For windward: Same pressures as surface 8 for Wind Direction A Surface 8: Same pressures as surface 8 for Wind Direction A Surface Same as surface 9 because it is sloping with respect to ridge Surface Wind Direction C Wall pressures Surfaces 1 and 5: Pressures vary along the roof; same pressures as surface 8 for Wind Direction A Surface Same pressures as surface 9 without internal pressures Overhang pressures From Section Wind Direction D Wall pressures Surfaces 1 and 3: Pressures vary along the roof; same pressures as surface 8 for Wind Direction A Surface 8: This surface will see pressures on top and bottom surfaces; they will add algebraically.

Case 1 includes the loadings analyzed as noted. A combination of windward PW and leeward PL loads is applied for other load cases. Only Load Cases 1 and 3 shown in Fig. Because of asymmetry, all four wind directions are considered when combining wind loads according to Fig.

For example, when combining wind loads in Case 3, there are four kinds of combinations of wind loads that need to be considered, which are shown as in Fig. Because of the low roof slope, the wind load acting on the roof is negligible here.

Wall Component Wall studs are 10 ft long and spaced 16 in. G Combinations of wind loads Arrows show the wind direction Wind Loads: G 2 ft Overhang typical Zones 2 and 3 are regarded as overhangs and thus there is no internal pressure component.

Data for the building are provided in Table G The building is less than 60 ft tall, so it is allowed to use Envelope low-rise provisions of Section Therefore, use part 1 of the Directional Procedure of Section It is not considered an essential facility, nor is it likely to be occupied by persons in a single area at one time. Wind speed map of Fig. G Building characteristics for U-shaped apartment 70 ft building ft ft 12 It is not located within a wind- borne debris region, so glazing protection is not required.

The mean roof height is the average of the eave and the peak: In accordance with Section Therefore, the overall dimensions L and B are used.

Wind Load Asce Presentation | Framing (Construction) | Structural Engineering

Case 1 includes the loadings determined in this example and shown in Tables G through G For Load Case 2, there are two loading conditions shown; both of them need to be checked independently. The eccentricities are calculated as follows: The equation is: The effective wind areas, A, for wall components are as follows: Controlling negative design pressure for window unit in Zone 4 of walls: Controlling negative pressure is obtained with positive internal pressure, and controlling positive pressure is obtained with negative internal pressure.

The edges called Zone 5 for the walls are arranged at exterior corners, as shown in Fig. The effective wind areas, A, for the roof trusses are as follows: Controlling negative pressure is obtained with positive inter- nal pressure, and controlling positive pressure is obtained with negative internal pressure.

The edges Zone 2 for the hip roof are arranged as shown in Fig. G Component and cladding roof pressure zones Wind Loads: G shows the dimensions and framing of the open buildings. The physical data are as listed in Table G Therefore, the Directional Procedure of Section The wind speed map associated with Risk Category I is in Fig.

Exposure The building is located in a wooded area. G Building characteristics for open building with gable roof Velocity Pressures Velocity pressure is determined using equations from the Standard: Minimum Design Wind Loadings Section Depending on the projected area of the roof and supporting structure, this minimum loading could govern and should be checked.

Positive numbers mean toward the surface; negative numbers mean away from the surface. The pressures are normal to roof surface Wind Pressure for Trusses and Roof Panels Calculated wind pressures for trusses and roof panels are summarized in Table G The panels and trusses are designed for the pressures indicated.

For trusses, two loading combinations need to be considered. The two loading cases are shown in Fig. The loadings shown for trusses are used for the design of truss and individual members. Note that Section G Pressure zones for panels and trusses Fig. G Loading cases for room trusses Comment The pressures determined are limit state design pressures for strength design.

Building data are as listed in Table G While Table 1. Wind speed map for this Category building is in Fig. Exposure The building is located in an open terrain area; according to Section Enclosure The building is designed to be enclosed. It is not located within a wind-borne debris region, so glazing protection is not required. G B Building characteristics 30 ft for domed roof structure B A C 20 ft B B A C B ft area where the wind speed exceeds mph and is within a mile of coastal mean high water or anywhere where the wind speed exceeds mph.

The example building is a low-rise building, so it can be considered a rigid building, and the value of the gust effect factor of 0. The value of qz varies from The force on the walls represents the total drag of the wind on the walls of the building, both windward and leeward.

Interpolation from Fig.

ASCE 7-05 to ASCE 7-10 Seismic Design Provisions.pdf

Cases A and B. G of this guide for the locations of points A, B, and C. The point is The building is assumed to be an enclosed building. The net pressure on any surface is the difference in the external and internal pressures on the opposite sides of that surface: G — However, since the building is round, the cases as shown do not apply.

There is a possibility of nonsymmetrical action by the wind, causing some torsion. Load Case 2, with the reduced calculated horizontal load and moment using eccentricity of 15 ft, could be applied to the cylindrical wall portion of the building. The designer could also use the Figs.

Therefore, it is valid to use Fig. Positive internal pressure provides controlling negative pressures, and negative internal pressure provides the controlling positive pressure.

These design pressures act across the roof surface interior to exterior. These pressures are for the front half of the dome. However, since all wind directions must be taken into account, and since each element would at some point be considered to be in the front half of the dome, each element must be designed for both positive and negative values. Building data are as shown in Table G Therefore, Chapter 27, part 1, Directional Procedure, is used.

The building is less than 60 ft tall, so it is possible to use low-rise provisions of part 1, Chapter It is not considered an essential facility, nor is it likely to be occupied by people in a single area at one time. Wind speed map for this building risk category is Fig. G Building characteristics for unusually shaped building 15 ft 30 ft 30 ft 70 ft 70 ft ft ft Exposure The building is located in a suburban terrain area; according to Section The example building is a low-rise building, so it can be considered rigid and the value of the gust effect factor of 0.

G of this guide. The overall dimensions for L and B are used. Figure For brevity, the case is not shown. The external roof pressures and their prescribed zones are shown in Fig. Minimum Design Wind Pressures Section This is checked as a separate load case. The application of this load is shown in Fig. Several exceptions are noted that require only the use of Load Case 1, the full orthogonal wind case, and Load Case 3, the diagonal wind case approximated by applying 75 percent of the loads to adjacent faces simultaneously.

The exceptions are building types that meet the requirements of Section D1. G Application of 16 psf minimum load case This exception is for one-story buildings less than 30 ft in height, so this example meets that exception and is required only to meet Load Cases 1 and 3. Load Case 1 is calculated above and shown applied in each orthogonal direction in Fig. Load Case 3 is the diagonal wind load case, applied in each of four directions as shown in Fig.

These values have been reduced Wind Loads: The controlling design pressures are given in Table G The edge zones for the walls are arranged at exterior corners, as shown in Fig.

The design pressures in Table G are the algebraic sum of external and internal pressures. The edge zones for the roof are arranged as shown in Fig. Design pressures include internal pressure of 3. The dimensions of the billboard sign are shown in Fig. The billboard sign data are as listed in Table G The wind speed map associated with Category I structures is Fig. Basic Wind Speed The wind speed map Fig. Exact location of the sign in Iowa is not important. Exposure The sign is located in an open area.

However, since wind loads on pipe columns are likely to be small as compared to sign, value of 0. It has been predetermined for this example. Determination of approximate frequency given in Section Frequency for the sign can be determined using structural properties and deformational characteristics of the sign.

For simplicity, a value of 0. In Eq. V is the basic 3-s gust wind speed in mph. Using the strength design Wind Loads: The designer is cautioned that the wind speed change in ASCE from year to year recurrence interval speeds in this case of a Category I structure affects the gust effect factor.

See Fig. Case A: Total force for Case A and C are comparable; 60, vs 57, lb. Eccentricity for Case B is higher than Case C. The purpose of this chapter is to clarify provisions of the Standard about which questions frequently arise. Is it possible to obtain larger scale maps of basic wind speeds see Figs. The wind speed contours in the hurricane prone region of the United States are based on hurricane wind speeds from Monte Carlo simulations and on estimates of the rate at which hurricane wind speeds attenuate to mph in Fig.

One such website is www. Wind speeds in the maps of ASCE are much higher than the ones in maps of ASCE ; does this mean the design for wind will be much stronger and cost more?

No; the wind speeds in the maps of ASCE are related to ultimate loads and strength design. The load factor for wind in Section 2. The load factor for wind for allowable stress design in Section 2. IBC wind speed map gives the 3-s at the project location. However, according to the Notes, the map is for Exposure C. If the project location is Exposure B, what is the proper wind speed to use?

If the design wind loads are to be determined for a building that is located in a special wind region shaded areas in Figs. Wind speeds in these regions may be substantially higher than the speeds indicated on the map, and the use of regional climatic data and consultations with a wind engineer or meteorologist are advised. How do I design for a Category 3 hurricane?

Table C Instead, load combination No. This load combination applies a 0. The 0.

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In ASCE , the loading combinations used 1. What exposure category should I use for the MWFRS if the terrain around my site is Exposure B but there is a large parking lot directly next to one of the elevations? The exposure depends on the size of the parking lot, its size relative to the building, and the number and type of obstructions in the area.

Section C The procedure is illustrated in Figs. Kzt need not be calculated when the height, H, is less than 15 ft in Exposures D and C, or less than 60 ft in Exposure B.

The value of Kzt is never less than 1. This is also true of masonry and reinforced-concrete walls. What about individual members of a truss? Roof trusses are considered to be components since they receive load directly from the cladding. In the case where the tributary area on any member exceeds ft2, Section A tower has a fundamental frequency of 2 Hz but has a height-to-width ratio of 6.

The energy in the turbulence spectrum is small for frequencies above 1 Hz. Hence, a tower with fundamental frequency of 2 Hz is not likely to be dynamically excited by wind.

The Commentary of the Standard has a good discussion on response of buildings and structures in turbulent wind in Section C The provisions of Fig.

Thus, they are not real wind-induced loads. These loads work adequately for buildings of the shapes shown in Fig. Sections Other loading conditions at the overhang, such as the pressures on the upper roof surface must be considered to obtain the total loads for connections between the roof and the wall.

Note 6 of Fig. Flat roof trusses are 30 ft long and are spaced on 4-ft centers. This is the area on which the selection of GCp should be based. Note, however, that Wind Loads: Roof trusses have a clear span of 70 ft and are spaced 8 ft on center. Metal decking consisting of panels 20 ft long and 2 ft wide is supported on purlins spaced 5 ft apart. No; although the length of a decking panel is 20 ft, the basic span is 5 ft. Therefore, GCp would be determined on the basis of 10 ft2 of effective wind area, and the corresponding wind load would be applied to a tributary area of 10 ft2.

Note that GCp is constant for effective wind areas less than 10 ft2. A masonry wall is 12 ft in height and 80 ft long. It is supported at the top and at the bottom.

Yes, in a limited way. ASCE and used the fastest-mile wind speed as the basic wind speed. With the adoption of the 3-s gust speed starting with ASCE , the values of certain parameters used in the determination of wind forces have been changed accordingly. The provisions of ASCE and should not be interchanged. What constitutes an open building? If a processing plant has a three-story frame with no walls but with a lot of equipment inside the framing, is this an open building? An open building is a structure in which each wall is at least 80 percent open see Section In calculating the wind force, F, appropriate values of Cf and Af would have to be assigned to the frame and to the equipment inside.

The solid area of the face of one tower panel projected on a plane of that face is 22 ft2. What area should be used to obtain the wind force per foot of tower height acting 1 normal to a tower face, and 2 along a tower diagonal? In calculating the wind forces acting on a trussed tower of square cross section see Fig. The calculated wind forces are the total forces acting on the tower. Equation When is z used and when is h used? Equations Whenever the subscript h is called for, it is understood that z becomes h mean roof height in the appropriate equations.

Additional information on these standards is provided in Section C The two standards specify test methods and performance standards. The Standard does not provide for across-wind excitation caused by vortex shedding.

How can one determine when vortex shedding might become a problem? Vortex shedding is almost always present with bluff-shaped cylindrical bodies. The intensity of excitation increases with aspect ratio height-to- width or length-to-breadth and decreases with increasing structural damping. Structures with low damping and with aspect ratios of 8 or more may be prone to damaging vortex excitation.

Although raindrops will increase the mean density of the air, the increase is small and may be neglected. For example, if the average rate of rainfall is 5 in. What wind loads do I use during construction? ASCE 7 does not address wind loads during construction. Is it possible to determine the wind loads for the design of interior walls? The Standard does not address the wind loads to be used in the design of interior walls or partitions.

Post-disaster surveys have revealed failure of interior walls when the building envelope has been breached. If the MWFRS can be separated such that there is a different system for each use, then the appropriate design wind speed associated with the appropriate use should be used.

He has been involved in research and education related to wind loads for the past 40 years.

ASCE 7-05 Wind and Seismic Load

Mehta with an award for distinguished service in wind engineering, and in he was elected to membership in the National Academy of Engineering.

He has been a practicing structural engineer since and has been involved in engineering issues related to disasters since These classes have been given in almost 20 states. ASCE Wind loads and anchor bolt design for petrochemical facilities. Minimum design loads for buildings and other structures.

ASTM BSI Cermak, J. Cook, N. Butterworth Publishers, London. Coulbourne, W. Davenport, A. Dyrbye, C. Eaton, K. Industrial Aerodynamics, 1 1 , 67— FEMA Building a saferoom inside your home. Georgiou, P. Wind Engrg. Holmes, J. Wind loading of structures. Spon Press, New York.

Hoerner, S. Fluid dynamics drag. The change allows the connections due to slip and bearing. Because the lower portion is stiff. Steel cantilever column systems ASCE contained provisions for steel ordinary. In previous editions. ASCE cantilevered column systems.

Figure 5. Revised vertical combination requirement. Item e in ASCE section The definition of base. According to ASCE AISC did not explicitly address cantilever column systems.

Two-stage analysis procedure. On the other hand. Weights in exterior bays can also be tributary was unconservative. The requirement of an in- used for weight distribution must not exceed ft2 plane offset to be greater than the length of an element 56 m2.

Therefore clarification is now provided that it tures. The tributary area element in the story below. By the exterior columns. Redundancy provisions tinued in the IBC. This modi. During the lightweight. Height limit for special steel plate House.

The definition of height-to-length ratio of shear walls and wall piers has been clarified4 for the purpose of determin- The conditions in section The IBC cal seismic force-resisting element resulting in overturning section ASCE prohibited the is accidental torsion with the torsional amplification factor use of ordinary and intermediate moment frames in higher Ax equal to 1. In other words. Requiring separate shear wall lines to meet the inclusion of this system in the permitted height increase of drift criterion is a recommendation.

New exceptions4 are added for SDC D and E ordinary and The revised definition of nonparallel systems irregular- intermediate moment frames. This modification was con. The following important ity clearly indicates that it exists only where the vertical items are worth noting: This research showed by full-scale tests that a thin. Allowable stress increase for load combinations with overstrength Collectors and their connections also shall be designed for these increased forces unless they are Where allowable stress design methodologies are used in designed for the load combinations with overstrength conjunction with load combinations with overstrength.

The purpose of the redundancy 1. The following changes have been made in ASCE sec. The intent was not to penalize wall designs 2. Forces calculated using the seismic provided the wall height does not exceed 8 ft. Collectors and their connections. Figure 7. Conditions where cal structural irregularity of Type 4 in Table Connections of diaphragms to vertical ele. Asymmetrical seismic-force-resisting systems.

Plywood shear walls that are 4 ft 1. The change also corrects the reference to the equivalent tion E or F and having a horizontal structural irregularity of Type 1a.

Increase in forces due to irregularities for seismic design As can be seen. These factors are material-dependent in allowable stress increase of 1. Figure 8: Height-to-length ratio of shear walls and wall piers. The second significant change is the introduction of a new repetitive member factor.

This redun- Several adjustment factors for the design of wood construc.

Wind Load Asce 7-05 Presentation

These three rows have been increase shall not be combined with increases in allowable consolidated into one row. Flow chart illustrating when dynamic analysis is required by ASCE Figure 9. ASCE establishes a new period-independent at short periods. SD1 is design. SDS is de. These structural irregularities are ceeding ft in height as long as the period remains less horizontal irregularities type 1a and 1b torsional and ex- than the previous threshold of 3.

Higher mode effects are still cause undesirable concentrations of inelastic displacements judged unlikely to be significant for regular structures ex. These two factors were in appendix Steel buckling-restrained braced frames 0. Supplement no. What is required to be included in the effective seismic starting at the long-period transition period TL. Items 2. The aforementioned in the effective seismic weight.

The minimum design base shear of 0. Equation After considerable discussion. ASCE has now 5. Figure 9 is a flow chart to determine when a dynamic analysis is required by ASCE In areas used for storage. In the course of the ATC project. Table 2. The values for the approximate period parameters Ct and x were also Steel eccentrically braced frames in accor.

Weight of landscaping and other materials at incorporated supplement no. Floor live load in public garages and open mistake. The analyses disturbingly showed story parking structures need not be included. Minimum design base shear sional response. Somehow these parameters were not carried for- dance with Table The longer predicted periods represented clarified.

Where the inclusion of storage loads adds ASCE ASCE processed supplement no. The added wording provides clarification and ensures that significant eccentricities exist. Vertically aligned points are also Ax shall not be less than one because it is possible for Ax to called for in the second paragraph. ASCE is applicable. Figure ASCE design response spectrum. A sentence was rigid diaphragms one example is diaphragms in open-front added in the first paragraph of ASCE section In section ASCE Eq.

Let us take the hy. Approximate period formula Story drift determination based on number of stories Story drift limits and not the computation of story drift In defining the applicability of ASCE Eq.

ASCE ASCE did requirement. The CQC modal response combination method. This is considered unjustified because this mini. Diaphragm and collector tion. Where the combined response for the ing drift. The design of many tall buildings. In these cases. Provision has been added for scaling of drifts where the near-fault minimum base shear equation ASCE Eq. The near-fault minimum. ASCE section Equation numbers in ASCE section This was not adopted by ASCE It should instead The provisions are the same as those included in the be used with the overstrength factor applied to Fpx.

The out-of. The reader into ASCE The modification has now been incorporated opment. Collector design force of ASCE The building separation to avoid damaging contact. The term QE. In ASCE This proposed change does have merit.

This is resolved4 by stating Fp equals 0. Building separation requirements of ASCE The importance factor is included in the maximum elastic sions for concrete and masonry walls assigned to SDC A.

The requirements now apply to all walls. That section. The new location is a clear indication that occupancy is canceled out. This is consistent chorage Forces. Large the weight of wall tributary to anchor.

Five of a flexible diaphragm Lf Fig. Anchorage of structural walls—ASCE requirements. B through F [Fig. The changes im. Members spanning between structures There are several substantive changes to the anchorage provisions. The multiplier ka increases from 1. Similar building. ASCE provides a gradual increase in an. This change results in rather significant increases in the anchorage design Openings or reentrant building force for taller walls in areas of moderate to low seismic corners hazard where SDS values are moderate to low.

This span is considered to be zero for a estimating these movements.

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