Precast/Prestressed Girder Help

Nomenclature and Printout Explanation (LFD)

Bridge Layout

SettingDescription
Overall width Overall width of the bridge.
Left Curb/Right Curb Width of the left and right curbs.
Curb-to-curb width Overall width minus curb widths.
Number of spans Total number of spans.
Number of lanes Total number of lanes.
Lane width Width of each lane.
Topping Thickness Concrete thickness of deck.
Suppl. Thickness Thickness of supplemental concrete layer added on top of the deck.
Haunch Thickness Thickness of build up over each beam flange.
Haunch Width Width of build up over each beam flange.

Concrete Properties

SettingDescription
C.I.P Cast-in-place topping.
f'c 28-day compressive strength of concrete.
Wc Weight of concrete.
Ec Modulus of elasticity of 28-day strength concrete.
f'ci Compressive strength of concrete at release of prestress.
Eci Modulus of elasticity of concrete at release.

Span Data

SettingDescription
Span Span number.
Pier-to-pier Centerline of pier to centerline of pier.
Precast Precast beam length.
Brg-to-brg Centerline of bearing to centerline of bearing at final conditions.
Pier CL-Precast Distance from centerline of left pier to left end of precast beam.
Release Distance between centerlines of temporary supports at release.
Bridge c/s M.I. Moment of inertia of the entire composite bridge cross-section.

Beam Data

SettingDescription
Span Span for which the data is listed in the particular section.
No. Beam line number.
ID Beam identification.
Loc-prev The distance to the centerline of a particular beam measured from the centerline of the previous beam to its left. For the first beam in a span, it is the distance between its centerline and the leftmost edge of bridge cross-section.
Area Gross area of cross-section of precast girder.
M.I. Gross moment of inertia of girder cross-section.
Height Height of the girder.
Yb Distance from bottom of girder to its center of gravity.
B-Topg Width of precast top flange.
B-Trib Tributary width over which loads will be calculated for design purposes.

Loads on Precast

Superimposed dead loads on precast beams.

SettingDescription
Span Span number.
Beam Beam number.
DC/DW

Load category. Either DC (Dead Load on Components) or DW (Dead Load on

Wearing Surface).

Type Load type, e.g., line load or point load.
Mag Magnitude of line load or point load.
Loc Location of point load measured from left bearing.

Diaphragm Loads

Superimposed dead loads of diaphragms on the precast beams.

SettingDescription
Span Span number.
Beam Beam number.
Mag Magnitude of concentrated diaphragm load.
Loc Location of point load measured from left bearing.

Loads on Composite/Supplemental

Superimposed dead loads on the compositesupplemental section.

SettingDescription
Span Span number.
DC/DW

Load category. Either DC (Dead Load on Components) or DW (Dead Load on

Wearing Surface).

Type Load type, e.g., area load, line load, or point load.
Mag Magnitude of area load, line load, or point load.
Loc Location of point load measured from the left pier centerline.
Width Width of area load.

Live Load Library

This section lists the details of the vehicular and pedestrian live loads acting on the composite section.

SettingDescription
ID Identification name of the vehicular live load.
Width Clearance and lane load width. See Figure 3.7.7A of AASHTO LFD.
Wheel Spg. Wheel spacing/gage width in transverse direction. (Standard Gage Width is 6'.)
Lane load (adjustable) UDL lane load defined in Figure 3.7.6B of AASHTO LFD.
Conc. Load Concentrated loads used with the lane load.
Mom Concentrated load for moment used with the lane load.
Shear Concentrated load for shear used with the lane load.
Truck Load Axle load of live load vehicle.
Spacing increment Indicated spacing increment between variable axles.
Mag. Magnitude of axle load.
Min. spac Minimum spacing between axle and previous axle.
Max. spac Maximum spacing between axle and previous axle.
Preceding uniform load Uniformly distributed load preceding the axle load.
Dist Distance between first axle of the truck and the end (farthest point) of the preceding load.
Mag Magnitude of uniformly distributed preceding load.
Len Length of the uniform preceding load.
Trailing uniform load Uniformly distributed load behind the axle load. Intended for use with railroad loading.
Dist Distance between the last axle of live load and the start (closest point) of the trailing load.
Mag Magnitude of uniformly distributed trailing load.
Len Length of the uniform trailing load.
Pedestrian live load Sidewalk live load.

Precast Data

SettingDescription
Section ID Girder identification.
Type Type of the girder.
Flng width: Top, Bot Top and bottom flange width of specified girder.
Flng thick: Top, Bot Thickness of top and bottom flanges of the specified girder.
Stems: No Number of stems of girder cross-section.
Top Stem width at its top.
Bot Stem width at its bottom.
Shear width Number of stems times average stem width.

General Bridge Data

SettingDescription
Bridge width Overall bridge width.
Curb-to-curb Bridge width minus curb widths.
Beam Spac. Lt/Rt Beam spacing. Distance from centerline of beam on left, Lt, and distance from centerline of beam on right, Rt.
Lane Width Design lane width.
No. of lanes Number of lanes across the bridge width.
Interior/Exterior Indicates if the beam is considered as exterior or interior beam for the purpose of calculating the live load distribution factor.
Skew Angle For skewed bridges, angle measured from centerline of pier to the normal to bridge centerline.

Topping Data

SettingDescription
Deck Thickness Concrete thickness of deck.
Suppl. Thickness Thickness of supplemental concrete layer added on top of deck.
Haunch Thickness of build-up over the beam flange.
SettingDescription
Thickness Haunch thickness.
Width Haunch width.
Effective Width Effective flange width of the section composed of precast beam and topping. Calculation as per LFD Art. 8.10.1 and Art. 9.8.1.1. If "wide top flange" checkbox is selected, the effective width is calculated as per Art. 9.8.3.

General Load Data

SettingDescription
Dead Loads on Precast Dead loads applied to the precast girder.
SettingDescription
DC/DW

Load category. Either DC (Dead load on components and attachments) or DW

(Dead load on wearing surface and utilities).

Type Load type, e.g., line or point load.
Mag Magnitude of line or point load.
Loc Location of diaphragm point load measured from left bearing.
Dead Load on Composite/Supplemental See Loads on Composite/Supplemental.
Moment Impact Moment impact factor (LFD Art. 3.8.2).
Shear Impact Shear impact factor (LFD Art. 3.8.2).
DL Dead Load.
ADL Additional Dead Load.

Load Factors

Shows the Gamma, Beta Dead Load, and Beta Live Load factors. Refer to AASHTO LFD Art. 3.22 and Art. 3.23.

SettingDescription
Group Group of loading from AASHTO LFD Art. 3.5 and Art. 3.22. Available options: Group I, I/IA, IB.

General Span Data

SettingDescription
Overall Length Overall length of precast girder.
Release Length Distance between temporary supports at release.
Design Length Bearing to bearing distance between girder supports at final.

Miscellaneous

SettingDescription
Kern pts Upper and lower kern points of the cross-section measured from the bottom of the beam.
Trans len mult Transfer length multipliers for bonded and debonded prestressing strands.
Dev len mult Development length multipliers for bonded and debonded prestressing strands.

Distribution Factors

SettingDescription
Dead Load Dead load distribution factor (computed or manual). (Listed separately for each of the Composite DL, Composite ADL, Supplemental DL, Supplemental ADL, and Supplemental Self weight loads).
Live Load - Girder
SettingDescription
Moment The DF for moment due to live load.
Shear The DF for shear due to live load.
Pedestrian Pedestrian load distribution factor (same as dead load DF).
Calculated or Manual Specifies whether the values were calculated by the program or user-defined. If any factors are calculated using the Lever rule, then those factors have an asterisk (*) next to them.

Section Properties

SettingDescription
Precast Section properties of precast beam alone.
Composite Section properties of precast beam plus topping. Same as Precast if no topping is used. If topping is used, results are for effective width of topping.
Supplemental Section properties of precast beam plus topping plus supplemental topping if used.
Area Area of Precast/Composite/Supplemental.
Total Height Total height of Precast/Composite/Supplemental.
*(Asterisk) Indicates where ratio of Ect/Ec is used for calculation of section properties for Composite and Supplemental.
Mom of Inertia Moment of inertia about center of gravity of Precast/Composite/Supplemental.
Ht. of c.g. Height of center of gravity of Precast/Composite/Supplemental measured from the bottom of the precast.
Density Density of concrete.
Self-weight Self-weight of Precast/Composite/Supplemental.
At 28-Days Strength, stresses, and elasticity of concrete at 28-days.
Strength Specified compressive strength of precast concrete, f'c, and topping, f'ct.
Max. comp: Top Maximum allowable compressive stress at the top of Precast/Composite/Supplemental (Art. 9.15.2.2).
Pos. Mom, Bot Maximum allowable compressive stress for positive moment at bottom of Precast.
Neg. Mom. Bot Maximum allowable compressive stress for negative moment at bottom of precast in ends of girder at piers at final (Art. 9.7.2).
Max tens: Top Maximum allowable tensile stress at the top of Precast/Composite/Supplemental (Art. 9.15.2.2).
Max tens: Bot Maximum allowable tensile stress at the bottom of Precast at final (Art. 9.15.2.2).
Elasticity Modulus of elasticity of Precast concrete at release, Eci.
Use transformed strands and rebar No" means strand and rebar is not transformed into concrete properties. "Yes" means strand and rebar are transformed into concrete section properties. An area and height of rebar to be transformed can be specified.

Prestressed Steel

SettingDescription
Prestressed Steel Information about prestressing strands.
End Pattern Location of strands at the end of the beam.
Ycg Center of gravity of strands measured from the bottom of the precast.
Mid Pattern Location of strands at the middle of the beam.
Ycg Center of gravity of strands measured from the bottom of the precast.
Strand Dia Diameter of one prestressing strand.
Strand Area Area of one prestressing strand.
Total strand area Total area of strands.
Trans. len, basic Basic transfer length (Art. 9.20.2.4).
Trans. len, bonded Transfer length for bonded strands.
Trans. len, debonded Transfer length for debonded strands.
Ult. strength (f's) Ultimate strength of prestressing strands, f's.
Initial prestress Jacking stress as a fraction of ultimate strength (Art. 9.15.1).
Initial pull Initial prestress times total strand area.
Dev len, basic Basic development length (Art. 9.2.7).
Dev len, bonded Development length for bonded strands.
Dev len, debonded Development length for debonded strands.

Reinforcing Steel

Reinforcing steel data (Art. 9.3.2).

SettingDescription
Tension steel Characteristics of tension reinforcement steel.
fy Specified yield strength of tension reinforcement.
fs Tensile stress in tension reinforcement.
Shear steel Characteristics of steel for shear reinforcement.
fsy Specified yield strength of shear reinforcement.
Modulus of elasticity Modulus of elasticity of tension and shear steel.

Prestress Losses

SettingDescription
Midspan
SettingDescription
Str. area Area of strands at midspan.
Ycg Location of center of gravity of strands at midspan measured from the bottom of the precast girder.
P-init Initial pull force.
Ecc Eccentricity of prestressing force from the centroid of the cross-section.
Hours to release Time between pouring of concrete and release of strands.
Rel Humid (RH) Mean annual ambient relative humidity (Art. 9.16.2).
Es Modulus of elasticity of prestressing steel strand.
Eci Modulus of elasticity of concrete, at release.
AASHTO Losses Loss of prestress by AASHTO Method (Art. 9.16).
Release Loss of prestress at release.
Final Final loss of prestress.
Steel relaxation RET CRs Loss due to relaxation of prestressing steel. (Eq. 9-10a)
Elastic shortening ES Loss of prestress due to elastic shortening. (Eq. 9-6)
Fcir Concrete stress at the center of gravity of the prestressing steel due to prestressing force and dead load of beam immediately after transfer. This value is computed at section of maximum moment.
Concrete shrinkage, SH Loss of prestress due to concrete shrinkage. (Eq. 9-4)
Concrete creep, CRc Loss of prestress due to creep of concrete. (Eq. 9-9)
Fcds Concrete stress at the center of gravity of prestressing steel due to all dead loads except the dead load present at the time prestressing force is applied.
Total Total loss of prestress at release/final.

Shielding and Reduced Initial Pulls

SettingDescription
Group Number of a group composed of one or two strands.
Strands Number of strands in a specified group.
Heights/End Location of center of gravity of the group of strands at both ends of the precast.
Heights/Mid Location of center of gravity of the group of strands at the midspan.
Shielding/End Length of shielding at midspan. Shielding extends half the specified length on each side of midspan.
Initial Pull Frac Initial pull fraction of strands represented as a fraction of ultimate strength of prestressing steel, f's.
Initial Pull/Str. Initial prestress force per strand.

Shear and Moment Envelope

SettingDescription
M Maximum moment due to a particular load component at a section.
V Corresponding shear associated with the above moment. This is the maximum absolute value for shear.
M+ Maximum positive moment due to live load, pedestrian load, or combined total maximum positive moment.
V Shear corresponding to M+. This is the maximum absolute value for shear.
M- Maximum negative moment due to live load, pedestrian load, or combined total maximum negative moment.
V Shear corresponding to M-. This is the maximum absolute value for shear.
Vmax Maximum absolute value of shear due to live load, pedestrian load, or combined total absolute maximum shear.
M Moment corresponding to Vmax.
Bearing Left and right bearing centerlines.
Trans Transfer location of strands taken as fifty strand diameters from the end of the precast and measured from the centerline of bearing.
H/2 Half of the overall depth of the member measured from the inner face of the bearing pad.
0.xL Point of 0.x of precast length measured from the left bearing.
Midspan Midspan of the girder.
Self wt. M and V due to self-weight of precast calculated for simply supported beam with "brg-to-brg" span length. Includes gamma factors.
DL-Prec M and V due to superimposed dead load acting on bare precast calculated for simply supported beam with "brg-to-brg" span length. Includes gamma and beta factors.
Deck + Haunch M and V due to deck and haunch weight acting on precast calculated for simply supported beam with "brg-to-brg" span length. Includes gamma and beta factors.
Supplement M and V due to the weight of supplemental layer acting on the composite section.
DL-Comp M and V due to superimposed dead loads acting on composite. Calculated for continuous beam model with "pier-to-pier" spans. Includes gamma and beta factors and DL tributary fraction.
DL-Supp M and V due to superimposed dead loads acting on supplemental. Calculated for continuous beam model with "pier-to-pier" spans. Includes gamma and beta factors and DL tributary fraction.
Restrain Restraining moments, M, due to continuity at piers if the user has selected to use these moments in design.
LL + I M and V envelopes due to selected truck and lane loads. Includes gamma, beta and impact factors.
Pedestrian M and V envelopes due to pedestrian load. Includes gamma, beta and impact factors.
Total Total M and V values due to all of the components listed above.

Moments and shears for Service and Factored load combinations.

Reactions

Note: Upward reactions are positive. Live load reactions are per lane with no distribution factor and no impact factor considered. Non-composite load types are per beam. Composite, supplemental, and pedestrian load types are per total bridge width. Individual reaction values (under both Service and Factored conditions) are reported at the Left and Right supports for the following load components: Self-wt, Deck + Haunch, Diaphragm, DL-Prec., DL-Comp, Supplemental, DL-Supp., Live Loads (Max and Min), and Pedestrian Loads (Max and Min).

Release Stresses

Note: Release stresses are shown for only half a beam due to the symmetry of prestress and self-weight. When the total stress exceeds the specified allowable stress, an asterisk is printed beside the exceeded value.
SettingDescription
Self wt Stress due to girder self-weight only (considering release span).
SettingDescription
Precast-Top Stress at the top of the precast due to self-weight.
Bottom Stress at the bottom of the precast due to self-weight.
Prestress Stress due to prestressing force only at transfer.
SettingDescription
Precast-Top Stress at the top of the precast due to the prestressing force.
Bottom Stress at the bottom of the precast due to the prestressing force.
Total Total stress at release (due to prestress and self-weight).
SettingDescription
Precast-Top Total stress at the top of the precast due to prestress and self-weight.
Bottom Total stress at the bottom of the precast due to prestress and self-weight.
*(Asterisk) Denotes stress exceeds allowable.
As-top Required area of steel at the top of precast to resist the total tension force in the concrete when the net top stress exceeds the allowable value. (LFD Art. 9.15.2.1)

Final Stresses: Positive Moment Envelope

Note: Final stresses are shown for half of a beam only. See Full Beam and Half Beam LFD and LRFD for more details. Stresses are checked for both halves of the beam and the controlling stress is reported. Positive sign of the stress indicates compression and negative indicates tension. When the total stress exceeds the specified allowable stress, an asterisk is printed beside the exceeded value. Final 1, 2, and 3 refer to the conditions described in LFD Art. 9.15.2.2 (a), (b), and (c).
SettingDescription
Prest/Precast-Top Final stress at the top of the precast due to prestressing force.
Prest/Bottom Final stress at the bottom of the precast due to prestressing force.
Self wt/Precast-Top Final stress at the top of the precast due to self-weight of the beam.
Self wt/Bottom Final stress at the bottom of the precast due to self-weight of the beam.
DL-Prec/Precast-Top G-Prec/Precast-Top Final stress at the top of the precast due to dead loads acting on the bare precast section.
DL-Prec/Bottom G-Prec/Bottom Final stress at the bottom of the precast due to dead loads acting on the bare precast section.
Topping/Precast-Top Final stress at the top of the precast due to the weight of the topping on the bare precast section.
Topping/Bottom Final stress at the bottom of the precast due to the weight of the topping on the bare precast section.
DL-Comp Final stress due to superimposed dead load on composite obtained for a model of multi-span continuous beam with pier-to-pier spans. Composite is made from precast girder and topping.
DL-Comp/Topping-Top Final stress at the top of the topping due to superimposed dead loads on the composite section.
DL-Comp/Precast-Top Final stress at the top of the precast due to superimposed dead loads on the composite section.
DL-Comp/Bottom Final stress at the bottom of the precast due to superimposed dead loads on the composite section.
Suppl. weight Final stresses due to the weight of the supplemental topping acting on the composite section.
DL-Suppl Final stresses due to weight of the supplemental topping acting on the composite section.
LL + I (+) Final stress due to positive moments generated by live load.
Total Total final stresses due to all of the components listed above.

Vertical Shear Art. 9.20

SettingDescription
*(Asterisk) Denotes an AASHTO code violation.
Vd Shear force at section due to unfactored dead loads (Art. 9.20).
Md Total unfactored dead load moment.
MI Maximum live load moment at section.
Vu Total factored shear force at section.
Mu Total factored moment at section (Art. 9.17 and Art. 9.18).
Vmu Factored shear occurring simultaneously with Mu.
Mmax Maximum factored moment at section due to externally applied loads.
Vi Factored shear force at section due to externally applied loads occurring simultaneously with Mmax (Art. 9.20.2.2).
fpe Compressive stress in concrete due to effective prestress forces only (after allowance for all prestress losses) at extreme fiber of section where tensile stress is caused by externally applied loads.
fd, psi/kPa Stress due to unfactored dead load at extreme fiber of section where tensile stress is caused by externally applied loads.
Mcr Cracking moment. Moment causing flexural cracking at section due to externally applied loads.
d Effective depth. Distance from extreme compressive fiber to centroid of prestressing force if under positive moment, or to centroid of deck reinforcement if under negative moment. Deck steel is assumed to be located at the midheight of the deck.
Vci-com Computed nominal shear strength. To apply the coefficients for lightweight concrete (Art. 9.20.2.5), if concrete density is less than 115 pcf, then it is considered as "all lightweight" concrete and a factor of 0.76 is used. For density greater than 115 pcf and less than 130 pcf, it is considered "sand-lightweight" concrete and a factor of 0.85 is used. For any other density, it is considered normal.
Vci-min Minimum nominal shear strength.
Vci Nominal shear strength provided by concrete when diagonal-cracking results from combined shear and moment.
fpc Compressive stress in concrete (after allowance for all prestress losses) at centroid of composite cross-section or at junction of web and flange when the centroid lies within the flange.
Vp Vertical component of effective prestress force at section (Art. 9.20.2.3).
Vcw Nominal shear strength provided by concrete when diagonal cracking results from excessive principal tensile stress in web (Art. 9.20.2.3). See "Vci-com" above for lightweight concrete coefficient used.
Vc Nominal shear strength provided by concrete.
Vs-reqd Nominal shear strength provided by web reinforcement. (Art. 9.20.1.3)
Vs-max Maximum allowable value of Vs. (Art. 9.20.3.1)
Av-com Computed area of web reinforcement within a distance of s = 12 inches.
Av-min Minimum area of web reinforcement within a distance of s = 12 inches.
Av Area of web reinforcement; the greater of Av-com and Av-min.
Av-prvd Area of web reinforcement provided in Stirrups dialog.
Phi*Vu/Vu Ratio of Nominal Shear Resistance to factored shear at section. Flagged by asterisk (*) if less then 1.0.
Vs-crit Critical nominal shear strength limit for web reinforcement spacing.
Max. spc Maximum spacing of the stirrups.

Anchorage Zone Reinforcement Art. 9.22.1

SettingDescription
Fpi Force in strand, just before release.
fs Stress in steel.
Abrst-req Required steel area to be provided within a distance d/4 from the end of the beam.
d/4 Distance (from end of beam) within which transverse reinforcement has to be provided.

Horizontal Shear Art. 9.20.4

SettingDescription
bv Width of contact surface between the precast top flange and topping being investigated for horizontal shear.
fsy Yield strength of non-prestressed shear reinforcement.
Vu Factored shear force at section. (Art. 9.20.1.3)
Vnh-req Ultimate horizontal shear stress.
d Effective depth. Distance from extreme compressive fiber to centroid of prestressing force if under positive moment, or to centroid of deck reinforcement if under negative moment. Deck steel is assumed to be located at the midheight of the deck.
Surf Area of the contact surface between the beam and topping.
s-max Maximum spacing of the stirrups for vertical and horizontal shear.
Avh-min Required minimum amount of horizontal shear reinforcement. (Art. 9.20.4.5(a))
Avh-sm Required amount of horizontal shear reinforcement if the contact surface is smooth, that is, not intentionally roughened. (Art. 9.20.4.3)
Avh-rg Required amount of horizontal shear reinforcement if the contact surface is intentionally roughened. (Art. 9.20.4.3)

Camber and Deflections

Camber and deflections due to various loads, at the following stages:

SettingDescription
Release Time at which the strands are cut in the prestressing bed.
Erection 30 to 60 days after release.
Final Long term.
Mult PCI camber and deflection multipliers.
Prestress Camber for prestress girder due to prestress only.
Self Wt. Deflection of girder under self-weight.
Deck + Haunch Girder deflection due to deck and haunch weight.
Supplemental Girder deflection due to supplemental layer weight.
DL-Prec Deflection of girder due to superimposed dead load on Precast.
Diaphragm Deflection of girder due to diaphragm loads.
DL-Comp SG-Comp Girder deflection due to superimposed dead load applied to composite model.
DL-Supp Deflection of girder due to superimposed dead load applied on composite supplemental section.
Live Load Deflection due to live load. This is shown only if the user has activated the option to calculate deflections.

Ultimate Capacity

Note: The ultimate capacity (Mu-prvd) of the beam is computed and compared against the required capacity (Mu-reqd). Depending on whether the section acts as a rectangular beam or as a T-Beam, Eq. 9-13 or Eq 9-14 is used. If the section is over reinforced, either Eq. 9-22 or Eq. 9-23 is used. The effect of any partially developed strands is accounted for by linearly reducing the nominal area of the strands at a given section along the beam in accordance with their development length. This is shown in the printout as the effective area of steel, A*s.
SettingDescription
f'c-eff Strength of the compression block concrete, either the beam concrete or deck concrete may be applicable.
beta1 Ratio of depth of equivalent compressive zone to distance from fiber of maximum compressive strain to the neutral axis. (Art. 8.16.2.7)
A*s Height of center of gravity of cross-section measured from the bottom of the precast.
Ycg Height of center of gravity of cross-section measured from the bottom of the precast.
p*(A*s/bd) Ratio of prestressing steel. (Art. 9.17 and Art. 9.19)
f*su Average stress in prestressing steel at ultimate load. (Art. 9.1.2)
a Approximate depth of compression block for ultimate capacity computations.
Mu-prvd Nominal moment of strength provided by the section. Must be greater than Mu-reqd.
Mu-reqd Required factored moment capacity.
Mcr Cracking moment.
Crkg. Ratio Cracking ratio. The ratio of the ultimate moment capacity to the cracking moment if the applied loads are increased to failure. Must be greater than 1.2 per Art. 9.18.2.
SettingDescription
fck (girder-final) Strength of the compression block concrete.
As Effective cross-sectional area of prestressing steel.
c Approximate depth of compression block for ultimate capacity computations.
Mu-prvd

Nominal moment of strength provided by the section. Must be greater than Mu.

Mu Required factored moment capacity.
db Depth of beam from max. compression edge to cg of steel.
Mfyst Capacity computed by yield of steel, under-reinforced section.
Mfcrc Capacity computed by crushing of concrete.
Mult Computer ultimate moment capacity.
Mprvd/reqd Ratio of ultimate moment capacity provided over required.

Detensioning

Note: Simulation of strand cutting operation. Represents the state of stress at the top and bottom of the beam as each group of strands is cut or detensioned. Generally this is of importance only to fabricators or consulting engineers designing straight patterns with debonded strands.
SettingDescription
Groups Number of group composed of one or two strands.
Loss Loss of prestress at release.
Grp Group number.
Str Number of strands in the group.
Ys Elevation of the center of gravity of the group of strands measured from the bottom of the beam.
E Elevation of the group of strands at the end of the beam.
M Elevation of the group of strands at the midspan of the beam.
Ft Stress at the top of the girder at a particular location.
Fb Stress at the bottom of the girder at a particular location.

Final Stresses: Negative Moment Envelope

Note: Final stresses are shown for half a beam only. Stresses are compared for both halves of the beam and the controlling stress is reported. Positive sign of the stress indicates compression and negative sign indicates tension. When the total stress exceeds the specified allowable stress, an asterisk is printed beside the exceeded value. For definition of individual terms, see Final Stresses: Positive Moment Envelope.

Reinforced Design

Note: The required quantity of negative moment reinforcement in the deck is computed based on loads, which act on the composite section only. The required amount of top (and bottom, if any) steel shown represents the amount of steel associated with the beam under consideration and should be provided within the effective area as defined in Art. 8.17.2.1. Top steel is assumed to be located at the mid-height of the deck. Bottom steel, occasionally necessary to avoid over-reinforced condition, is assumed to be located at two inches from the bottom flange of the precast (compression face).
SettingDescription
fy Specified yield strength of reinforcement.
phi Strength capacity reduction factor. For reinforcement over piers phi = 0.9 (Art. 8.16.1.2.2).
f'c Compressive strength of concrete at 28 days. End sections are designed using f'c (Art. 9.7.2.3.2).
Sec Sections for which reinforcement is calculated.
Dist Distance of the section measured from the left pier centerline.
Mu-reqd Total required factored moment.
b Width of compression block.
hf Thickness of flange under compression.
bw Web width of the beam.
d Effective depth. Distance from extreme compressive fiber to centroid of reinforcement in tension. Deck steel is assumed to be located at the midheight of the deck.
d' Distance from compression fiber center of gravity to centroid of compression steel (computed if necessary), which is assumed to be located 2.00 inches from the bottom flange of the beam.
1.2*Mcr 1.2 * cracking moment causing flexural cracking at section due to externally applied loads.
Asb Required amount of compression steel (bottom) for negative moments. Precast/Prestressed Girder computes the required amount of tension steel (Ast) in the deck (top), but occasionally bottom steel, assumed to be located at 2.0 inches from the bottom of the lower flange, is required to avoid an over-reinforced condition.
Ast-r Required amount of deck steel to resist total factored negative moment at a section. Amount required is only for the beam under consideration. It should be placed in the deck in accordance with Art. 8.17.2.1.1.
Ast-p Area of steel provided by the user in the Negative Moment Continuity Steel Tab on the Rebar dialog.
M-prvd Moment capacity computed based on user provided steel area.

Reinforced Design (b) POSITIVE MOMENT AT PIERS

SettingDescription
Dist Distance of the section measured from the left pier centerline.
Ms Positive Design Moment. Includes restraining moment and live load.
b Width of Compression block.
hf Thickness of Flange under Compression.
bw Web Width of Beam.
d Effective Depth. Distance from extreme compressive fiber to centroid of reinforcement in tension. Steel is assumed to be located at the 2 inches or 50 mm from the bottom flange of the beam.
d' Distance from compression fiber center of gravity to centroid of compression steel (computed if necessary), which is assumed to be 2 inches or 50 mm from the top of the deck.
1.2Mcr Cracking moment.
Asb Required amount of positive moment steel to resist larger of 1.2Mcr or Ms moment at a section. Amount required is only for the beam under consideration.
Ast Additional compression steel if required.

Design Summary

Note: A comprehensive summary of the entire design is reported at the end of the output file. The summary compiles all important information regarding Beam and Span Information, Strand Data, Concrete Properties, Release Stresses, Ultimate Capacity, Debonding Percentages, Allowable and Computed Envelope Stresses, and Camber and Deflection values at mid-span.
Parent topic: Nomenclature and Printout Explanation (LFD)