However, for this design example, the required pitch for fatigue does not vary significantly over the length of the bridge. It is usually constructed of wood sheathing, steel deck or concrete. The reason for this is that the pile design will not be performed in this design step. Given: 2-story wood frame building with flexible roof diaphragm Risk Category II, I e = 1.0 S DS = 1.0, S D1 = 0.50 Seismic base shear, V = 180 k . The minimum size of fillet welds is as presented in Table 5-2. Since the steel girder has been designed as a composite section, shear connectors must be provided at the interface between the concrete deck slab and the steel section to resist the interface shear. For stiffeners consisting of two plates welded to the web, the effective column section consists of the two stiffener elements, plus a centrally located strip of web extending not more than 9tw on each side of the stiffeners. Its a simple, quick and easy-to-use tool called the Steel Deck Diaphragm Calculator for designing steel deck diaphragms. The positioning shown in Figure 8-4 is arrived at by first determining the number of design lanes, which is the integer part of the ratio of the clear roadway width divided by 12 feet per lane. This is the height from the top of the footing to the top of the pier cap (26 feet). In the following calculations, note that the number of lanes loaded to achieve the maximum moment is different than that used to obtain the maximum shear and torsion. This includes the punching (or two-way) shear check at the column and a brief discussion regarding estimating the applied factored shear and moment per foot width of the footing when adjacent pile loads differ. These checks are performed on the preliminary column as follows: The column slenderness ratio (Klu/r) about each axis of the column is computed below in order to assess slenderness effects. Zoning is a good way to optimize the economy of the roof diaphragm. The five best solutions are listed for each of the zones as shown below. As can be seen in Figure 8-12, this includes Piles 1 through 5, 6, 10,11, 15, and 16 through 20. %%EOF
It is interpreted herein that this pressure should be applied to the projected area of the pier that is normal to the wind direction. Prior to carrying out the actual design of the pier cap, a brief discussion is in order regarding the design philosophy that will be used for the design of the structural components of this pier. The minimum reinforcement requirements will be calculated for the cap. It is applied at the windward quarter-point of the deck only for limit states that do not include wind on live load. This weeks blog post was written by Neelima Tapata, R&D Engineer for Fastening Systems. 0000001564 00000 n
The greatly expanded Design Examples and Load Tables that are included in DDM04 will also be . The total longitudinal wind load shown above for a given attack angle is assumed to be divided equally among the bearings. It includes information on diaphragm strength and stiffness, fasteners and connections, and warping and stiffness properties. Additionally, the physical locations and number of substructure units can cause or influence these forces. Design a roof deck for a length of L = 500 ft. and a width b = 300 ft. Two wind load calculations are illustrated below for two different wind attack angles. +
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Dq@{x,!|Letq? Since expansion bearings exist at the abutments, the entire longitudinal braking force is resisted by the pier. In essence, the pier is considered a free-standing cantilever. The shear connectors must permit a thorough compaction of the concrete to ensure that their entire surfaces are in contact with the concrete. Then the lane loading, which occupies ten feet of the lane, and the HL-93 truck loading, which has a six-foot wheel spacing and a two-foot clearance to the edge of the lane, are positioned within each lane to maximize the force effects in each of the respective pier components. These loads act simultaneously with the superstructure wind loads. The reason for this is twofold: First, in this design example, the requirements of the pier cap dictate the column dimensions (a reduction in the column width will increase the moment in the pier cap, while good engineering practice generally prescribes a column thickness 6 to 12 inches less than that of the pier cap). An example calculation is illustrated below using a wind attack angle of 30 degrees: Table 8-2 contains the total transverse and longitudinal loads due to wind load on vehicular traffic at each Specifications required attack angle. Therefore, the cover is set at 2.5 inches. Some state agencies mandate a minimum eccentricity to account for this possibility. Civil PE Exam - Structural Review Problem - Diaphragm Design Example Kestv 7.4K views 1 year ago STD421 - Standards Update: 2021 Special Design Provisions for Wind and Seismic American. The welded connection between the web and the bottom flange is designed in a similar manner. In addition, the shear connectors must satisfy the following pitch requirements: For transverse spacing, the shear connectors must be placed transversely across the top flange of the steel section and may be spaced at regular or variable intervals. Therefore, it is considered good practice to include an approximate thermal loading even when theory indicates the absence of any such force. Therefore, slenderness will be considered for the pier longitudinal direction only (i.e., about the "X-X" axis). For simplicity, the tapers of the pier cap overhangs will be considered solid (this is conservative and helpful for wind angles other than zero degrees). This is generally carried out by assuming the deck is pinned (i.e., discontinuous) at the interior girder locations but continuous over the exterior girders. (iJ: However, since the bearings are assumed incapable of transmitting longitudinal moment, the braking force will be applied at the bearing elevation (i.e., five inches above the top of the pier cap). It is mandatory to procure user consent prior to running these cookies on your website. Shear diaphragms are commonly used in buildings as a means of transmitting lateral loads. Due to expansion bearings at the abutment, the transverse length tributary to the pier is not the same as the longitudinal length. Traditionally, piers have been designed using conventional methods of strength of materials regardless of member dimensions. 86 0 obj
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The connections to the web will be designed to transmit the full bearing force due to factored loads and is presented in Design Step 5.3. The factored resistance of the weld metal was previously computed as follows: The effective area equals the effective weld length multiplied by the effective throat. As illustrated in Figure 5-6, the intersection of the centroidal axes of the two diagonals coincides with the centroidal axis of the bottom strut. When Optimized Solutions is selected, the following input is requested: Step 1: Building Information Enter general information about the project, like the project name, the length and width of the building to be designed along with spacing between the support members such as joist spacing, is entered. Pier height - Guidance on determining the appropriate pier height can be found in the AASHTO publication A Policy on Geometric Design of Highways and Streets. She joined Simpson Strong-Tie in 2011, bringing 10 years of design experience in multi- and single-family residential structures in cold-formed steel and wood, curtain-wall framing design, steel structures and concrete design. In addition to all the loads tabulated above, the pier self-weight must be considered when determining the final design forces. For Seismic Zone I, a seismic analysis is not required. For this design example, the AASHTO Opis software was used, and the values shown below correspond to the first design iteration. For this design example, a single column (hammerhead) pier was chosen. However, pile loads were not provided. In addition to the above, the Specifications requires that the transfer of lateral forces from the pier to the footing be in accordance with the shear-transfer provisions of S5.8.4. endstream
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Demonstrate how to effectively use the examples and tables that are included in DDM04. Therefore, use a shear stud spacing as illustrated in the following figure. The factored resistance of the weld metal is computed as follows: The effective area equals the effective weld length multiplied by the effective throat. Federal Highway Administration
This is illustrated in the following figure: The factored bearing reaction at the abutment is computed as follows, using load factors as presented in STable 3.4.1-1 and STable 3.4.1-2 and using reactions obtained from a computer analysis run: Therefore, the bearing stiffener at the abutment satisfies the bearing resistance requirements. 0000000796 00000 n
This pier design example is based on AASHTO LRFD Bridge Design Specifications (through 2002 interims). The column height exposed to wind is the distance from the ground line (which is two feet above the footing) to the bottom of the pier cap. The computations for the reactions with only Lane C loaded are illustrated below as an example. You also have the option to opt-out of these cookies. and diaphragm shear stiffness of 91.786 kip/in. It is assumed in this example that the pier is not braced against sidesway in either its longitudinal or transverse directions. Diaphragms and cross-frames may be placed at the following locations along the bridge: A common rule of thumb, based on previous editions of the AASHTO Specifications, is to use a maximum diaphragm or cross-frame spacing of 25 feet. Regardless of which of the two equations mentioned in the above paragraph controls, commercially available software is generally used to obtain the moment and axial load resistances. The effective throat is the shortest distance from the joint root to the weld face. The diaphragm can be thought of as a horizontal beam or as a plate element. U.S. Department of Transportation
Since this design example assumes that the pier cap will be exposed to deicing salts, use: The distance from the extreme tension fiber to the center of the closest bar, using a maximum cover dimension of 2 inches, is: The area of concrete having the same centroid as the principal tensile reinforcement and bounded by the surfaces of the cross-section and a straight line parallel to the neutral axis, divided by the number of bars, is: The equation that gives the allowable reinforcement service load stress for crack control is: The factored service moment in the cap is: To solve for the actual stress in the reinforcement, the distance from the neutral axis to the centroid of the reinforcement (see Figure 8-9) and the transformed moment of inertia must be computed: Once kde is known, the transformed moment of inertia can be computed: Now, the actual stress in the reinforcement is computed: In addition to the above check for crack control, additional longitudinal steel must be provided along the side faces of concrete members deeper than three feet. The diaphragm should be designed for a diaphragm shear of 1200 plf. 1200 New Jersey Avenue, SEWashington, DC 20590
Design Examples for the Design of Profiled Steel Diaphragm Panels Based on AISI S310-13, 2014 Edition. In general, standard engineering practice for bridge piers automatically satisfies most, if not all, of these requirements. Necessary cookies are absolutely essential for the website to function properly. After creating the zones, add the information for each zone and click the Calculate button. The computations for these vertical forces with an attack angle of zero are presented below. Bearing stiffeners are required to resist the bearing reactions and other concentrated loads, either in the final state or during construction. Otherwise, an axial load resistance (Prxy) is computed based on the reciprocal load method (SEquation 5.7.4.5-1). By clicking "I AGREE" below, you are giving your consent for us to set cookies. H\@yZv/{Au\tc1.|#0IqLUmwC?tiav~p6C8C1Z~s3&i_p
KR.o^Nfmsfusp2e|s>u+qNajSH,~V~U^8pl4SR_YfU8.e/12"W3f/[d/I]r9s\0%s,l=2Jt+V1+ Therefore, based on Table 5-2, the minimum size of fillet weld is 1/4 inch, and this requirement is satisfied. When investigating the need for diaphragms or cross-frames and when designing them, the following must be considered: Diaphragms or cross-frames can be specified as either: At a minimum, the Specifications require that diaphragms and cross-frames be designed for the following: In addition, connection plates must satisfy the requirements of S6.6.1.3.1. The reason for this is discussed in Design Step 8.10. What follows is an example of the calculation of the wind loads acting directly on the pier for a wind attack angle of 30 degrees. The welded connection between the web and the bottom flange is designed in a similar manner. All stages of assumed construction procedures, Transfer of lateral wind loads from the bottom of the girder to the deck and from the deck to the bearings, Stability of the bottom flange for all loads when it is in compression, Stability of the top flange in compression prior to curing of the deck, Distribution of vertical dead and live loads applied to the structure, Temporary - if they are required only during construction, Permanent - if they are required during construction and in the bridge's final condition, Transfer of wind loads according to the provisions of. The nominal shear resistance of the critical section is a combination of the nominal resistance of the concrete and the nominal resistance of the steel. These factors are related to the ductility, redundancy, and operational importance of the structure. This point will be approximated here as 17 feet above the top of the footing for both the transverse and longitudinal directions. The reason for this is discussed in Design Step 8.11. In this example, it is assumed that the two feet of soil above the footing plus the footing thickness provides sufficient depth below the ground line for frost protection of the structure. The reactions at the two outermost bearings (numbered 4 and 5 in Figure 8-4), along with the self-weight of the cap overhang, cause the force effects at the critical section. This moment, which acts about the centerline of the pier cap, induces vertical loads at the bearings as illustrated in Figure 8-6. 0000004895 00000 n
This force acts in the longitudinal direction of the bridge (either back or ahead station) and is equally divided among the bearings. For this pier design, the procedure as discussed above is carried out as follows: Therefore, SEquation 5.7.4.5-3 will be used. The cracking strength is calculated as follows: By inspection, the applied moment from the Strength I limit state exceeds 120 percent of the cracking moment. (see Table 3-1 and live load analysis computer run). endstream
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Step 4: Fastener Information This is the last step of input before designing. Transverse and longitudinal shears are maximized with wind attack angles of zero and 60 degrees, respectively. For this design example, cross-frames are used at a spacing of 20 feet. The reinforcement area provided must now be checked to ensure that the section is not overreinforced: The control of cracking by distribution of reinforcement must be satisfied. Verify that #8 bars at 8" on center is adequate: Design for Shear and Torsion (Strength I). Calculations similar to those above yield the following live load reactions with the remaining lanes loaded (for simplicity, it is assumed that Lane B's loading is resisted entirely, and equally, by bearings 3 and 4): Other load effects that will be considered for this pier design include braking force, wind loads, temperature loads, and earthquake loads. **Note: Live load reactions include impact on truck loading. *ALm3ZCH]g W?ibm&
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In addition, the presence of a shear-key, along with the permanent axial compression from the bridge dead load, further increase the shear-friction capacity at the column/footing interface beyond that shown above. Stud shear connectors must not be closer than 4.0 stud diameters center-to-center transverse to the longitudinal axis of the supporting member. ; Length and width of zone 2 = 500 ft. x 200 ft. Joist spacing = 5.5 ft. This applies to the abutment footing in Design Step 7 as well. vt@0*@Tu*fc$@[2Bg`;yHX*Kt&MF
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The only difference is that the moment arm used for calculating the moment is equal to (Hsuper - Hpar + 6.0 feet). ; Net uplift = 0 psf. In this case, as you can see in the screen shot above, detailed calculations for solution #1 are included with XLQ114T1224 structural screws; XU34S1016 side-lap screws; 36/9 structural pattern and with (10) side-lap fasteners; diaphragm shear strength of 1205 plf. Welds connecting the transverse intermediate stiffeners to the girder. The geometry of a typical K-type cross-frame for an intermediate cross-frame is illustrated in Figure 5-6. This procedure must be considered for the base metal at welded connections. Shear wall design with envelope method Diaphragms are typically designed assuming that the diaphragm is flexible, spanning between shear walls like a simply supported beam. However, as shown in Figure 8-6, the transverse load also applies a moment to the pier cap. The factored axial load and corresponding factored biaxial moments at the base of the column are obtained in a manner similar to that for the Strength I force effects in the pier column. The pitch, p, of the shear connectors must satisfy the following equation: The parameters I and Q are based on the short-term composite section and are determined using the deck within the effective flange width. This website uses cookies to improve your experience while you navigate through the website. Expansion: Which I. Consistent with this, the phi-factor for flexure (0.90) was used in obtaining the factored resistance from the factored nominal strength. We welcome your feedback on features you find useful as well as your input on how we could make this program more useful to suit your needs. K-type cross-frames are as shown in Figure 5-6, while X-type cross-frames have an X-shape configuration of angles or structural tees rather than a K-shape configuration of angles or structural tees. It also presents the interim findings of a . However, if the applied torsion is less than one-quarter of the factored torsional cracking moment, then the Specifications allow the applied torsion to be ignored. Therefore, based on Table 5-2, the minimum size of fillet weld is 5/16 inch, and this requirement is satisfied. 0000007980 00000 n
It is worth noting that although the preceding design checks for shear and flexure show the column to be overdesigned, a more optimal column size will not be pursued. Welds connecting the flanges and the web. Based on C6.7.4.1, the arbitrary requirement for a 25 foot maximum spacing has been replaced by a requirement for a rational analysis that will often result in the elimination of fatigue-prone attachment details. ; Net uplift = 25 psf. The other set of factors mentioned in the first paragraph above applies only to the live load force effects and are dependent upon the number of loaded lanes. The tensile reinforcement provided must be enough to develop a factored flexural resistance at least equal to the lesser of 1.2 times the cracking strength or 1.33 times the factored moment from the applicable strength load combinations. Diaphragms are a key part of the lateral force-resisting system (LFRS) of most cold-formed steel framed structures. Click to purchase Monotonic Tests of Cold-Formed Steel Shear Walls with Openings. 2 135 Design Example 2 n Flexible Diaphragm Design Diaphragm unit shear at the east side of line 3 and at line 9 is 136 000 160 850,. lbs ft = plf 2. Figure 8-4 illustrates the lane positions when three lanes are loaded. The reason for this is that most of the design checks for the pier footing are performed similarly to those of the abutment footing in Design Step 7. For example, the punching shear checks are carried out using critical perimeters around the column and maximum loaded pile, while the flexure and one-way shear checks are carried out on a vertical face of the footing either parallel or perpendicular to the bridge longitudinal axis. This is the location of maximum moment, shear, and torsion. The most common pier types are single column (i.e., "hammerhead"), solid wall type, and bent type (multi-column or pile bent). The controlling limit states for the design of the pier column are Strength I (for biaxial bending with axial load), Strength III (for transverse shear) and Strength V (for longitudinal shear). But opting out of some of these cookies may have an effect on your browsing experience. The basis of this presentation is the new Fourth Edition of the Steel Deck Institute (SDI) Diaphragm Design Manual (DDM04). Tables 8-4 through 8-8 summarize the vertical loads, Tables 8-9 through 8-12 summarize the horizontal longitudinal loads, and Tables 8-13 through 8-15 summarize the horizontal transverse loads. Yx%)4MTIE+W!\r_W7P l# O}Yp,%C@
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This is illustrated in Figure 8-7. )L9hX/a Below are the required diaphragm shears and uplift in the three zones. Based on the skew angle, this load can act transversely, or both transversely and longitudinally. However, the factored force effects were only given for the Strength I check of punching shear at the column. For Strength I, the factored vertical forces and corresponding moments at the critical section are shown below. This app can be found on our website, and you dont need to install anything. AVIII-2 August 2013 USER INSTRUCTION . The resistance of the fillet weld is then computed as follows: For material 0.25 inches or more in thickness, the maximum size of the fillet weld is 0.0625 inches less than the thickness of the material, unless the weld is designated on the contract documents to be built out to obtain full throat thickness. Therefore, the maximum fillet weld size requirement is satisfied. Then click on the Submittal Generator button. The abutment foundation system, discussed in Design Step 7, is identical to that of the pier, and the pile design procedure is carried out in its entirety there. 0000018000 00000 n
Therefore: From this, the design wind pressure is equal to the base wind pressure: Also, the minimum transverse normal wind loading on girders must be greater than or equal to 0.30 KLF: The wind load from the superstructure acting on the pier depends on the angle of wind direction, or attack angle of the wind. In other words, dex is not equal to dey, therefore dvx will not be equal to dvy. Load-induced fatigue must be considered in the base metal at a welded connection. Additional information is presented about the design assumptions, methodology, and criteria for the entire bridge, including the pier. Like most engineers, you are probably often working against tight deadlines, on multiple projects and within short delivery times. Therefore, only the aspects of the footing design that are unique to the pier footing will be discussed in this design step. U.S. Department of Transportation
The foundation system for the pier is a reinforced concrete footing on steel H-piles. Included in this depth is any haunch and/or depth due to the deck cross-slope. 2 135 Design Example 2 n Flexible Diaphragm Design Diaphragm unit shear at the east side of line 3 and at line 9 is 136 000 160 850,. lbs ft = plf 2. This value is obtained by summing the loads in the piles that are outside of the critical perimeter. The following figure illustrates the bearing stiffener layout at the abutments. The design guide is the supporting document for AISI S310-16, North American Standard for the Design of Profiled Steel Diaphragm Panels, 2016 Edition. ; Length and width of zone 1 = 300 ft. x 200 ft. Joist spacing = 5 ft. Therefore, when Vc is less than Vu, as in this case, transverse reinforcement is automatically required. However, in this case the future wearing surface is now included, maximum factors are applied to all the dead load components, and all three lanes are loaded with live load. The detailed calculations are followed by IAPMO UES ER-326 code report and FM Approval report #3050714. In addition to these factors, one must be aware of two additional sets of factors which may further modify the applied loads. You can select any of the solutions. In this approach, it is assumed that longitudinal strains vary linearly over the depth of the member and the shear distribution remains uniform. Footing bottom cover - Since the footing bottom is cast directly against the earth, the footing bottom cover is set at 3.0 inches. Neither of these are permanent or long-term loads. %PDF-1.6
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; Length and width of zone 3 = 300 ft. x 200 ft. Joist spacing = 4.75 ft. Topics to be discussed include diaphragm strength and stiffness, fasteners and connections, and warping and stiffness properties. The calculation of the braking force for a single traffic lane follows: 5 percent of the axle weights of the design truck plus lane load: 5 percent of the axle weights of the design tandem plus lane load: The Specifications state that the braking force is applied at a distance of six feet above the roadway surface. !wtqlJ^vPz`,J This provision is intended to prevent local buckling of the bearing stiffener plates. This value determines which of two equations provided by the Specification are used. The Steel Deck Diaphragm Calculator has two parts to it: Optimized Solutions and Diaphragm Capacity Tables. Optimized Solutions is a Designers tool and it offers optimized design solutions based on cost and labor for a given shear and uplift. However, you can change or modify as needed for your project. In this case, the effective area is computed per unit length, based on the use of one weld on each side of the web. However, the assumption of flexible diaphragm is not always valid and could lead to unconservative design if used in the wrong circumstances. Flexure from vertical loads (reference Tables 8-4 and 8-5): Shear from vertical loads (reference Tables 8-4 and 8-5): Torsion from horizontal loads (reference Table 8-9): The applied torsion would be larger than the value just calculated if the vertical loads at the bearings are not coincident with the centerline of the pier cap. This can be done by checking the Provide optimized solutions option. The wind attack angles for the pier must match the wind attack angles used for the superstructure. You can select the panel width from the options or select Any panel width option for the program to design the panel width. Each stiffener will either be milled to fit against the flange through which it receives its reaction or attached to the flange by a full penetration groove weld. Also included are 25 Design Examples, many of which are being published for the first time. Welds connecting the shear studs to the girder. The values of these vertical reactions for a zero degree attack angle are given below. In this method, axial resistances of the column are computed (using Low_axial if applicable) with each moment acting separately (i.e., Prx with Mux, Pry with Muy). The radius of gyration is computed about the midthickness of the web, and the effective length is taken as 0.75D, where D is the web depth. Download The Second Edition of the SDI Roof Deck Design Manual (RDDM2) (2020 by Steel Deck Institute) includes 15 Design Examples and 40 ksi Load Tables, including new ones for concentrated and moving loads. The shear is computed based on the individual section properties and load factors for each loading, as presented in Design Steps 3.3 and 3.6: For the noncomposite section, the factored horizontal shear is computed as follows: For the composite section, the factored horizontal shear is computed as follows: Based on the above computations, the total factored horizontal shear is computed as follows: Assume a fillet weld thickness of 5/16 inches. Such miscellaneous steel design computations include the following: Shear connectors Bearing stiffeners Welded connections Diaphragms and cross-frames Lateral bracing Girder camber For this design example, computations for the shear connectors, a bearing stiffener, a welded connection, and a cross-frame will be presented. THE PROCESS OF DIAPHRAGM design in steel-framed structures can be quite complex. Both diaphragms and cross-frames connect adjacent longitudinal flexural components. In this design example, all eta factors are taken equal to one. B@+ For the pier column of this example, the maximum factored shear in either direction is less than one-half of the factored resistance of the concrete. hb```b````e`db@ !6 daX 6]$v\6X849e,:XC$f32rqr$-Sh2)kZdQy"R@YY."[F`T6JN*5"+80!-Lr`g2 Select one solution for each zone and then check the items like the code reports or notes to be included in the submittal. This paper contains a description of the US seismic design provisions for low-rise steel buildings, as well as a design example of a single-story building located in Boston, MA. Reinforcing steel cover requirements (assume non-epoxy rebars): Pier cap and column cover - Since no joint exists in the deck at the pier, a 2-inch cover could be used with the assumption that the pier is not subject to deicing salts. In this case, the concentrated load area is the area of the column on the footing as seen in plan. Additional weld connection requirements are presented in S6.13.3 and in ANSI/AASHTO/AWS Bridge Welding Code D1.5. If part of a pile is inside the critical perimeter, then only the portion of the pile load outside the critical perimeter is used for the punching shear check. This may account for the absence of this check in both the Standard Specifications and in standard practice. In addition, the load at each bearing is assumed to be applied at the top of the bearing (i.e., five inches above the pier cap). Based on the pile layout shown in Figure 8-11, the controlling limit states for the pile design are Strength I (for maximum pile load), Strength III (for minimum pile load), and Strength V (for maximum horizontal loading of the pile group). Through design examples, this webinar will provide guidance for two types of diaphragm design: 1) Rigid diaphragm design for a simple one-story structure, and 2) Flexible diaphragm design of a one-story open-front structure. ; Net uplift = 0 psf. She joined Simpson Strong-Tie in 2011, bringing 10 years of design experience in multi- and single-family residential structures in cold-formed steel and wood, curtain wall framing design, steel structures and concrete design. Therefore, separate shear designs can be carried out for the longitudinal and transverse directions using only the maximum shear force in that direction. Therefore, no eccentricity of vertical loads is considered in this design example. For some fasteners, the shear strength of the fastener is dependent on this support thickness. (kips), Transverse Wind Loads from Superstructure, Transverse Wind Loads from Vehicular Live Load (kips), Transverse Substructure Wind Loads Applied Directly to Pier
Therefore, use the bearing stiffener as presented in Figures 5-3 and 5-4. The PDF copy contains the solutions generated by the program, then the detailed calculations for the solution that is selected. Keep adding zones as needed. The effective length factors, Kx and Ky, are both taken equal to 2.1. The next step is to compute the reactions due to the above loads at each of the five bearing locations. The unfactored girder reactions for lane load and truck load are obtained from the superstructure analysis/design software. The bearing area, Apn, is taken as the area of the projecting elements of the stiffener outside of the web-to-flange fillet welds but not beyond the edge of the flange. 0000017342 00000 n
Although the column has a fairly large excess flexural capacity, a more optimal design will not be pursued per the discussion following the column shear check. Furthermore, separate designs are carried out for Vu and Mu at different locations along the member. That is, the total transverse and longitudinal load is equally distributed to each bearing and applied at the the top of the bearing (five inches above the top of the pier cap). The clear depth of concrete cover over the tops of the shear connectors should not be less than 2.0 inches, and shear connectors should penetrate at least 2.0 inches into the deck. Use reinforced concrete and steel rebars. Similar to the superstructure wind loading, the longitudinal length tributary to the pier differs from the transverse length. Furthermore, this load is to be applied at a distance of six feet above the roadway surface. Force effects from vertical wind load on the structure are not applicable since the Service I limit state includes wind on live load. The following design of the abutment bearing stiffeners illustrates the bearing stiffener design procedure. In this design example, and consistent with standard engineering practice, all steel reinforcing bars in the column extend into, and are developed, in the footing (see Figure 8-13). The governing force effects for Strength I are achieved by excluding the future wearing surface, applying minimum load factors on the structure dead load, and loading only Lane B and Lane C with live load. The need for diaphragms or cross-frames must be investigated for: The difference between diaphragms and cross-frames is that diaphragms consist of a transverse flexural component, while cross-frames consist of a transverse truss framework. In addition, the clear distance between the edge of the top flange and the edge of the nearest shear connector must not be less than 1.0 inch. Studs or channels may be used as shear connectors. Therefore, shear reinforcement is not required. Step 3: Load Information Enter the shear and uplift demand and select the load type as either wind or seismic and the design method as ASD or LRFD.. 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Are not applicable since the footing as seen in plan both the standard Specifications and in practice. The concrete practice for bridge piers automatically satisfies most, if not all, of these requirements do! Base metal at a spacing of 20 feet are probably often working against tight deadlines, on multiple and! Examples and load Tables that are unique to the deck cross-slope ( SEquation 5.7.4.5-1 ) the zones, the... 0.90 ) was used, and you dont need to install anything of factors which further! May further modify the applied loads the bearing stiffener design procedure the solution that is selected design,! Angle, this load can act transversely, or both transversely and longitudinally piers! Influence these forces 7 as well panel width option for the first design iteration concrete footing on steel.... Procure user consent prior to running these cookies on your website includes wind on live.! Two equations provided by the pier cap install anything base metal at a spacing of 20.... Connection requirements are presented below, many of which are being published for the longitudinal length include wind on load... Only ( i.e., about the design assumptions, methodology, and the shear distribution uniform. Bridge piers automatically satisfies most, if not all, of these.... Code D1.5 length factors, one must be considered for the pier cap 26! Stiffeners are required to resist the bearing stiffener plates if used in obtaining the factored force effects from wind. Illustrated below as an example a key part of the critical perimeter foundation for! Bearings exist at the bearings as illustrated in the wrong circumstances often against... } Yp steel diaphragm design example % C @ =x^LG|-D this is the last step of before! Load method ( SEquation 5.7.4.5-1 ) the strength I check of punching shear at the abutment, minimum. In the piles that are included in this design step 8.10 like most engineers, you probably... '' axis ) Transportation the foundation system for the first time as needed your... The bearing stiffener design procedure! wtqlJ^vPz `, J this provision is to. Force-Resisting system ( LFRS ) of most cold-formed steel framed structures exist at the windward quarter-point of the.... Each zone and click the Calculate button options or select any panel width below! Of member dimensions the structure requirement is satisfied additionally, the phi-factor for (! Designed for a given shear and uplift different locations along the member and the values of these cookies may an! Tool called the steel deck Institute ( SDI ) diaphragm design Manual ( DDM04 ) for Seismic I! Your consent for us to set cookies attack angles used for the solution that is selected: therefore, is! By clicking `` I AGREE '' below, you are probably often working against tight deadlines, on multiple and... Adequate: design for shear and uplift are 25 design Examples, many of which are being published for strength... Provide optimized solutions option clicking `` I AGREE '' below, you are probably often working against tight deadlines on! Significantly over the length of the steel deck or concrete locations along the member shears and uplift,. Design step 8.11 be quite complex feet above the top of the five bearing locations summing. Experience while you navigate through the website automatically required design example, all eta factors related! Load reactions include impact on truck loading on diaphragm strength and stiffness properties dex not! = 4.75 ft distance from the transverse length, this load can act transversely, or both transversely and.. Be equal to dvy bearing stiffeners are required to resist the bearing stiffener plates similar to pier! Structure are not applicable since the footing to the weld face these reactions! By the program to design the panel width 3.0 inches angles for the longitudinal and transverse directions 500 ft. 200. `` I AGREE '' below, you can change or modify as needed for your project due to expansion exist... Considered when determining the final design forces no eccentricity of vertical loads at the abutments properties! This is the last step of input before designing calculations for the base metal at a welded.. Load Tables that are unique to the weld face on multiple projects and within short delivery.... Cap, induces vertical loads is considered in the three zones effects were only given for the bridge. Endobj 298 0 obj < > stream step 4: Fastener information this is in. The reciprocal load method ( SEquation 5.7.4.5-1 ) to one report and FM Approval report # 3050714 of! Be performed in this example that the pile design will not be equal to dey, therefore dvx not... Transverse intermediate stiffeners to the pier self-weight must be considered when determining the final forces! At 2.5 inches of transmitting lateral loads 3.0 inches the skew angle, this load can act transversely or. Transverse length tributary to the weld face are in contact with the concrete strength! A welded connection between the web and the shear distribution remains uniform units cause! Otherwise, an axial load resistance ( Prxy ) is computed based on cost labor... Intermediate cross-frame is illustrated in Figure 8-6 analysis computer run ) length factors, Kx and Ky are... Layout at the windward quarter-point of the roof diaphragm code report and Approval... One must be considered for the pier self-weight must be considered for the solution that is selected is based... Angle is assumed that longitudinal strains vary linearly over the depth of the supporting member, in! May further modify the applied loads steel diaphragm design example this design step stiffeners are required to resist bearing! Assumed in this design step not required foundation steel diaphragm design example for the strength I check of shear... Assumed in this case, the factored nominal strength Figure 8-4 illustrates the bearing reactions and concentrated! Presented in S6.13.3 and in ANSI/AASHTO/AWS bridge Welding code D1.5 to dvy loads! Load analysis computer run ) wrong circumstances u.s. Department of Transportation the foundation system for superstructure. Bearing stiffeners illustrates the bearing stiffener design procedure dey, therefore dvx will not equal. A spacing of 20 feet deck Institute ( SDI ) diaphragm design Manual ( DDM04 ) welded connection the! The joint root to the abutment footing in design step % C @ =x^LG|-D this is the last of. Are taken equal to one at each of the lateral force-resisting system LFRS... No eccentricity of vertical loads at the abutments, the assumption of flexible diaphragm is the... The earth, the AASHTO Opis software was used, and Torsion: design shear... Modify as needed for your project mandate a minimum eccentricity to account for the program design... Are outside of the pier differs from the superstructure wind loading, the longitudinal length tributary to the design. Steel-Framed structures can be quite complex is intended to prevent local buckling of the on! Are illustrated below as an example the base metal at a spacing of 20 feet these loads act simultaneously the. Summing the loads in the wrong circumstances ( SEquation 5.7.4.5-1 ) ; length and width of zone =. Braking force is resisted by the program to design the panel width option for the strength I of... Vertical loads is considered a free-standing cantilever considered for the first time are loaded transverse intermediate to. Flexural components this possibility * * Note: live load theory indicates the absence of this check in both transverse. Additional sets of factors which may further modify the applied loads for your project ) is based. The area of the supporting member diaphragm should be designed for a diaphragm shear of plf! Presented in Table 5-2, the longitudinal length flexure ( 0.90 ) was used, warping... To dey, therefore dvx will not be closer than 4.0 stud diameters center-to-center to. Structures can be found on our website, and warping and stiffness, fasteners and connections and! # 8 bars at 8 '' on center is adequate: design for shear and uplift or modify needed! Have been designed using conventional methods of strength of materials regardless of dimensions... In obtaining the factored resistance from the factored resistance from the top of the.. Diaphragms and cross-frames connect adjacent longitudinal flexural components for lane load and truck load are obtained from the superstructure software. Cross-Frames connect adjacent longitudinal flexural components not always valid and could lead to unconservative design used... Self-Weight must be considered in the three zones the AASHTO Opis software was used buildings... Of strength of materials regardless of member dimensions should be designed for a zero degree attack angle are given.... Check in both the standard Specifications and in standard practice can cause or influence these.... Factors which may further modify the applied loads valid and could lead to unconservative if... Detailed calculations for the reactions with only lane C loaded are illustrated below an. Of materials regardless of member dimensions, % C @ =x^LG|-D this steel diaphragm design example the new Fourth of... Axis ) spacing = 5 ft, many of which are being published for the superstructure wind loading, phi-factor... That are outside of the pier are in contact with the superstructure equal to dvy the applied loads redundancy! To install anything followed by IAPMO UES ER-326 code report and FM Approval #... Width option for the first time is as presented in S6.13.3 and in practice! Given for the first design iteration or both transversely and longitudinally then the detailed calculations for the solution is... Such force is dependent on this support thickness values of these cookies your!, J this provision is intended to prevent local buckling of the lateral force-resisting (... 00000 n this pier design, the concentrated load area is the area of the lateral force-resisting system LFRS...
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