Upload
nguyentu
View
238
Download
2
Embed Size (px)
Citation preview
2011 Louisiana Transportation Conference
New Seismic Design Requirements in Louisiana
SDR Engineering Consultants, Inc.January 11, 2011
Mohsen Shahawy, PhD., PE
2011 Louisiana Transportation Conference
Seismic Zones. Until relatively recently, seismic design criteria depended solely upon the seismic zone in which a structurewas located. Zones were regions in whichseismic ground motion, corresponding to acertain probability of occurrence, was within certain ranges.
2011 Louisiana Transportation Conference
New design requirements recognized that structure performance during a seismic event depends not only on the severity of sub-surface rock motion, but also on the type of soil upon which a structure is founded
2011 Louisiana Transportation Conference
2011 Louisiana Transportation Conference
The soil condition at the site is the additional variable that must now be dealt with.
While this adds another element to an already complicated procedure, it does incorporateestablished knowledge about the effect of soil properties during an earthquake intoseismic design criteria.
2011 Louisiana Transportation Conference
In general, the process leading to the classification of the Seismic Design Category involves several steps and clearly, the procedure for establishing the seismic classification of a structure has become more complex.
2011 Louisiana Transportation Conference
Develop the Seismic Zone classification map for Louisiana based on a study of all parishes in the state and accounting for the existing soil classification for each Parish.
Objectives
2011 Louisiana Transportation Conference
ProcedureStep 1: Site Class Definitions
A site shall be classified as A though F in accordance with the site class definitions.
Table 1. Basis for Seismic Design Criteria in Model Codes and Standards
Seismic Zones Seismic Site Classification
Classifications 0, 1, 2, 3, 4 A, B, C, D, E, F
Criteria for Classification
LocationLocation, Structure Use, & Soil Type
2011 Louisiana Transportation Conference
2011 Louisiana Transportation Conference
ProcedureStep 2 : Determine Peak Ground Acceleration coefficient
(PGA) and the short- and long period spectral acceleration coefficients (SS and Sl , respectively)
Step 3 : Determine zero, short, and long-period sitefactors, FPGA , Fa , and Fv
2011 Louisiana Transportation Conference
Procedure
Table 1. Basis for Seismic Design Criteria in Model Codes and Standards
Step 4 : Calculate the Response spectrum
2011 Louisiana Transportation Conference
For each Parish:
Divide into 3 or 4 zones based on Zip code
Perform analysis and determine SD1=Fv*Sl
Determine Zone Classification
2011 Louisiana Transportation Conference
AccelerationCoefficient, S
D1Seismic Zone
S ≤ 0.15 1D1
0.15 < S ≤ 0.30 2D1
0.50 < S 4D1
0.30 < S ≤ 0.50 3D1
Seismic Performance ZonesEach bridge shall be assigned to one of the four seismic zones in accordance with Table 3.10.6-1
Table 3.10.6-1 Seismic Zones
2011 Louisiana Transportation Conference
Parish Zip code PGA Ss Sl
Site Class FPGA Fa Fv SD1=Fv*Sl As=FPGA*PGA Zone
Acadia70543 0.027 0.06 0.028 D 1.6 1.6 2.4 0.07 0.043
170578 0.027 0.059 0.028 D 1.6 1.6 2.4 0.07 0.04370526 0.026 0.059 0.028 D 1.6 1.6 2.4 0.07 0.042
Allen70648 0.028 0.062 0.029 D 1.6 1.6 2.4 0.07 0.045
170655 0.028 0.064 0.03 D 1.6 1.6 2.4 0.07 0.04571463 0.031 0.07 0.032 D 1.6 1.6 2.4 0.08 0.050
Ascension
70737 0.029 0.064 0.029 E*2 2.5 2.5 3.5 0.10 0.073
170778 0.029 0.063 0.029 E* 2.5 2.5 3.5 0.10 0.07370774 0.029 0.064 0.029 E* 2.5 2.5 3.5 0.10 0.07370769 0.029 0.065 0.03 E* 2.5 2.5 3.5 0.11 0.07370346 0.028 0.062 0.029 E* 2.5 2.5 3.5 0.10 0.070
Assumption70390 0.027 0.058 0.027 E* 2.5 2.5 3.5 0.09 0.068
171355 0.025 0.055 0.026 E* 2.5 2.5 3.5 0.09 0.063
Beauregard
70634 0.03 0.067 0.03 D 1.6 1.6 2.4 0.07 0.048
170653 0.03 0.066 0.03 D 1.6 1.6 2.4 0.07 0.04870652 0.029 0.063 0.029 D 1.6 1.6 2.4 0.07 0.04670660 0.028 0.063 0.029 D 1.6 1.6 2.4 0.07 0.045
Bienville
71068 0.039 0.091 0.04 C 1.2 1.2 1.7 0.07 0.047
171016 0.039 0.09 0.04 C 1.2 1.2 1.7 0.07 0.04771008 0.041 0.096 0.043 C 1.2 1.2 1.7 0.07 0.04971028 0.043 0.1 0.044 C 1.2 1.2 1.7 0.07 0.052
Bossier71064 0.044 0.101 0.044 E 2.5 2.5 3.5 0.15 0.110
171006 0.041 0.096 0.042 E 2.5 2.5 3.5 0.15 0.10371051 0.039 0.091 0.04 E 2.5 2.5 3.5 0.14 0.098
2011 Louisiana Transportation Conference
Parish Zip code PGA Ss Sl
Site Class FPGA Fa Fv SD1=Fv*Sl As=FPGA*PGA Zone
Caddo71082 0.042 0.096 0.042 E 2.5 2.5 3.5 0.15 0.105
171107 0.04 0.092 0.041 E 2.5 2.5 3.5 0.14 0.100
71047 0.038 0.087 0.038 E 2.5 2.5 3.5 0.13 0.095 1
Calcasieu
70661 0.027 0.06 0.027 E 2.5 2.5 3.5 0.09 0.068
170665 0.026 0.058 0.026 E 2.5 2.5 3.5 0.09 0.065
70611 0.027 0.06 0.027 E 2.5 2.5 3.5 0.09 0.068
70607 0.026 0.057 0.026 E 2.5 2.5 3.5 0.09 0.065
Caldwell71418 0.042 0.098 0.044 E 2.5 2.5 3.5 0.15 0.105
171435 0.04 0.094 0.043 E 2.5 2.5 3.5 0.15 0.100
Cameron
70631 0.023 0.051 0.024 E*2 2.5 2.5 3.5 0.08 0.058
170643 0.023 0.05 0.024 E* 2.5 2.5 3.5 0.08 0.058
70630 0.025 0.056 0.026 E* 2.5 2.5 3.5 0.09 0.063
70645 0.024 0.054 0.025 E* 2.5 2.5 3.5 0.09 0.060
Catahoula71343 0.036 0.084 0.039 E* 2.5 2.5 3.5 0.14 0.090
171340 0.038 0.088 0.04 E* 2.5 2.5 3.5 0.14 0.095
71368 0.039 0.091 0.042 E* 2.5 2.5 3.5 0.15 0.098
Claiborne71038 0.049 0.114 0.048 C 1.2 1.2 1.7 0.08 0.059
171040 0.047 0.109 0.046 C 1.2 1.2 1.7 0.08 0.056
71003 0.045 0.104 0.045 C 1.2 1.2 1.7 0.08 0.054
Concordia71354 0.034 0.079 0.037 E*2 2.5 2.5 3.5 0.13 0.085
171334 0.037 0.086 0.04 E* 2.5 2.5 3.5 0.14 0.093
70753 0.031 0.071 0.033 E* 2.5 2.5 3.5 0.12 0.078
2011 Louisiana Transportation Conference
Parish Zip code PGA Ss Sl
Site Class FPGA Fa Fv SD1=Fv*Sl As=FPGA*PGA Zone
Desoto71063 0.036 0.083 0.037 C 1.2 1.2 1.7 0.06 0.043
171046 0.037 0.084 0.037 C 1.2 1.2 1.7 0.06 0.044
71052 0.037 0.084 0.037 C 1.2 1.2 1.7 0.06 0.044
East Baton Rouge
70791 0.031 0.069 0.032 E 2.5 2.5 3.5 0.11 0.078
170810 0.03 0.066 0.03 E 2.5 2.5 3.5 0.11 0.075
70815 0.03 0.067 0.031 E 2.5 2.5 3.5 0.11 0.075
East Carroll
71254 0.058 0.138 0.056 E*2 2.5 2.5 3.5 0.20 0.145
271286 0.054 0.13 0.053 E* 2.5 2.5 3.5 0.19 0.135
71276 0.052 0.124 0.051 E* 2.5 2.5 3.5 0.18 0.130
East Feliciana
70761 0.041 0.094 0.041 D 1.6 1.6 2.4 0.10 0.066
170722 0.032 0.072 0.033 D 1.6 1.6 2.4 0.08 0.051
70777 0.031 0.07 0.032 D 1.6 1.6 2.4 0.08 0.050
Evangeline70554 0.029 0.064 0.03 E 2.5 2.5 3.5 0.11 0.073
170586 0.029 0.065 0.031 E 2.5 2.5 3.5 0.11 0.073
Franklin71295 0.043 0.101 0.045 E 2.5 2.5 3.5 0.16 0.108
271336 0.041 0.096 0.044 E 2.5 2.5 3.5 0.15 0.103
71232 0.048 0.115 0.049 E 2.5 2.5 3.5 0.17 0.120
Grant
71432 0.037 0.085 0.039 D 1.6 1.6 2.4 0.09 0.059
171467 0.035 0.08 0.037 D 1.6 1.6 2.4 0.09 0.056
71454 0.035 0.081 0.037 D 1.6 1.6 2.4 0.09 0.056
71417 0.034 0.078 0.036 D 1.6 1.6 2.4 0.09 0.054
Iberia
70538 0.025 0.055 0.026 E*2 2.5 2.5 3.5 0.09 0.063
170560 0.026 0.057 0.027 E* 2.5 2.5 3.5 0.09 0.065
70563 0.026 0.058 0.027 E* 2.5 2.5 3.5 0.09 0.065
2011 Louisiana Transportation Conference
Parish Zip code PGA Ss Sl
Site Class FPGA Fa Fv SD1=Fv*Sl As=FPGA*PGA Zone
Iberville70788 0.029 0.063 0.029 E* 2.5 2.5 3.5 0.10 0.073
170740 0.029 0.065 0.03 E* 2.5 2.5 3.5 0.11 0.073
70764 0.029 0.064 0.029 E* 2.5 2.5 3.5 0.10 0.073
Jackson
71251 0.041 0.095 0.043 C 1.2 1.2 1.7 0.07 0.049
171226 0.042 0.099 0.044 C 1.2 1.2 1.7 0.07 0.050
71268 0.042 0.098 0.043 C 1.2 1.2 1.7 0.07 0.050
71238 0.044 0.103 0.045 C 1.2 1.2 1.7 0.08 0.053
Jefferson
70094 0.027 0.059 0.027 E*2 2.5 2.5 3.5 0.09 0.068
170072 0.026 0.058 0.027 E* 2.5 2.5 3.5 0.09 0.065
70036 0.026 0.054 0.026 E* 2.5 2.5 3.5 0.09 0.065
70067 0.025 0.055 0.026 E* 2.5 2.5 3.5 0.09 0.063
Jefferson Davis
70549 0.025 0.056 0.026 D 1.6 1.6 2.4 0.06 0.040
170591 0.026 0.058 0.027 D 1.6 1.6 2.4 0.06 0.042
70532 0.028 0.062 0.029 D 1.6 1.6 2.4 0.07 0.045
Lafayette70520 0.028 0.061 0.029 E*2 2.5 2.5 3.5 0.10 0.070
170592 0.026 0.058 0.027 E* 2.5 2.5 3.5 0.09 0.065
70529 0.027 0.059 0.028 E* 2.5 2.5 3.5 0.10 0.068
Lafourche70301 0.026 0.057 0.026 E* 2.5 2.5 3.5 0.09 0.065
170374 0.024 0.053 0.025 E* 2.5 2.5 3.5 0.09 0.060
70357 0.022 0.048 0.024 E* 2.5 2.5 3.5 0.08 0.055
LaSalle71371 0.036 0.083 0.038 E 2.5 2.5 3.5 0.13 0.090
171465 0.039 0.091 0.041 E 2.5 2.5 3.5 0.14 0.098
71342 0.035 0.082 0.038 E 2.5 2.5 3.5 0.13 0.088
Lincoln71270 0.045 0.106 0.046 C 1.2 1.2 1.7 0.08 0.054
171275 0.044 0.104 0.045 C 1.2 1.2 1.7 0.08 0.053
71235 0.048 0.113 0.048 C 1.2 1.2 1.7 0.08 0.058
2011 Louisiana Transportation Conference
Parish Zip code PGA Ss Sl
Site Class FPGA Fa Fv SD1=Fv*Sl As=FPGA*PGA Zone
Livingston70785 0.031 0.068 0.031 E 2.5 2.5 3.5 0.11 0.078
170449 0.029 0.065 0.03 E 2.5 2.5 3.5 0.11 0.073
70754 0.03 0.067 0.031 E 2.5 2.5 3.5 0.11 0.075
Madison71282 0.049 0.116 0.049 E*2 2.5 2.5 3.5 0.17 0.123
271232 0.048 0.115 0.049 E* 2.5 2.5 3.5 0.17 0.120
Morehouse71264 0.05 0.118 0.05 E 2.5 2.5 3.5 0.18 0.125
271220 0.054 0.129 0.053 E 2.5 2.5 3.5 0.19 0.135
71250 0.061 0.144 0.057 E 2.5 2.5 3.5 0.20 0.153
Natchitoches71070 0.038 0.088 0.04 E 2.5 2.5 3.5 0.14 0.095
171457 0.036 0.082 0.037 E 2.5 2.5 3.5 0.13 0.090
71468 0.034 0.078 0.035 E 2.5 2.5 3.5 0.12 0.085
Orleans70129 0.028 0.06 0.028 E*2 2.5 2.5 3.5 0.10 0.070
170131 0.027 0.058 0.027 E* 2.5 2.5 3.5 0.09 0.068
70124 0.027 0.06 0.028 E* 2.5 2.5 3.5 0.10 0.068
Ouachita
71203 0.048 0.114 0.049 D 1.6 1.6 2.4 0.12 0.077
1
71202 0.046 0.109 0.047 D 1.6 1.6 2.4 0.11 0.074
71292 0.045 0.107 0.047 D 1.6 1.6 2.4 0.11 0.072
71225 0.046 0.109 0.047 D 1.6 1.6 2.4 0.11 0.074
71291 0.047 0.111 0.048 D 1.6 1.6 2.4 0.12 0.075
Plaquemines70083 0.024 0.051 0.025 E*2 2.5 2.5 3.5 0.09 0.060
170037 0.026 0.057 0.027 E* 2.5 2.5 3.5 0.09 0.065
70091 0.021 0.045 0.023 E* 2.5 2.5 3.5 0.08 0.053
2011 Louisiana Transportation Conference
Parish Zip code PGA Ss Sl
Site Class FPGA Fa Fv SD1=Fv*Sl As=FPGA*PGA Zone
Pointe Coupee
70715 0.031 0.07 0.033 E* 2.5 2.5 3.5 0.12 0.078
170762 0.03 0.068 0.031 E* 2.5 2.5 3.5 0.11 0.075
70753 0.031 0.071 0.033 E* 2.5 2.5 3.5 0.12 0.078
Rapides
71328 0.033 0.077 0.036 E 2.5 2.5 3.5 0.13 0.083
171430 0.031 0.07 0.033 E 2.5 2.5 3.5 0.12 0.078
71409 0.033 0.074 0.034 E 2.5 2.5 3.5 0.12 0.083
71360 0.033 0.076 0.035 E 2.5 2.5 3.5 0.12 0.083
Red River71019 0.037 0.086 0.038 E 2.5 2.5 3.5 0.13 0.093
171068 0.039 0.091 0.04 E 2.5 2.5 3.5 0.14 0.098
Richland
71269 0.048 0.113 0.048 E 2.5 2.5 3.5 0.17 0.120
271259 0.044 0.104 0.046 E 2.5 2.5 3.5 0.16 0.110
71232 0.048 0.115 0.049 E 2.5 2.5 3.5 0.17 0.120
Sabine
71429 0.033 0.075 0.033 C 1.2 1.2 1.7 0.06 0.040
171419 0.036 0.081 0.035 C 1.2 1.2 1.7 0.06 0.043
71449 0.035 0.077 0.034 C 1.2 1.2 1.7 0.06 0.042
St. Bernard70085 0.026 0.057 0.027 E*2 2.5 2.5 3.5 0.09 0.065
170043 0.027 0.059 0.026 E* 2.5 2.5 3.5 0.09 0.068
St. Charles
70070 0.027 0.059 0.027 E*2 2.5 2.5 3.5 0.09 0.068
170057 0.027 0.06 0.028 E* 2.5 2.5 3.5 0.10 0.068
70087 0.027 0.06 0.028 E* 2.5 2.5 3.5 0.10 0.068
2011 Louisiana Transportation Conference
Parish Zip code PGA Ss Sl
Site Class FPGA Fa Fv SD1=Fv*Sl As=FPGA*PGA Zone
St. Helena70441 0.032 0.073 0.034 D 1.6 1.6 2.4 0.08 0.051
170422 0.031 0.07 0.033 D 1.6 1.6 2.4 0.08 0.050
70453 0.031 0.07 0.032 D 1.6 1.6 2.4 0.08 0.050
St. James70090 0.027 0.06 0.028 E*2 2.5 2.5 3.5 0.10 0.068
170086 0.028 0.061 0.028 E* 2.5 2.5 3.5 0.10 0.070
70723 0.028 0.062 0.028 E* 2.5 2.5 3.5 0.10 0.070
St. John70068 0.028 0.062 0.028 E*2 2.5 2.5 3.5 0.10 0.070
170049 0.028 0.061 0.028 E* 2.5 2.5 3.5 0.10 0.070
70051 0.028 0.061 0.028 E* 2.5 2.5 3.5 0.10 0.070
St. Landry70358 0.021 0.045 0.023 E*2 2.5 2.5 3.5 0.08 0.053
170570 0.028 0.064 0.03 E* 2.5 2.5 3.5 0.11 0.070
70512 0.028 0.063 0.029 E* 2.5 2.5 3.5 0.10 0.070
St. Martin70582 0.027 0.06 0.028 E*2 2.5 2.5 3.5 0.10 0.068
170517 0.028 0.061 0.029 E* 2.5 2.5 3.5 0.10 0.070
St. Mary70538 0.025 0.055 0.026 E*2 2.5 2.5 3.5 0.09 0.063
170392 0.024 0.053 0.025 E* 2.5 2.5 3.5 0.09 0.060
70544 0.026 0.057 0.027 E* 2.5 2.5 3.5 0.09 0.065
St. Tammany
70461 0.029 0.064 0.03 E 2.5 2.5 3.5 0.11 0.073
170431 0.031 0.069 0.032 E 2.5 2.5 3.5 0.11 0.078
70447 0.03 0.066 0.031 E 2.5 2.5 3.5 0.11 0.075
2011 Louisiana Transportation Conference
Parish Zip code PGA Ss Sl
Site Class FPGA Fa Fv SD1=Fv*Sl As=FPGA*PGA Zone
Tangipahoa70454 0.03 0.067 0.031 D 1.6 1.6 2.4 0.07 0.048
170422 0.031 0.07 0.033 D 1.6 1.6 2.4 0.08 0.050
70444 0.032 0.073 0.034 D 1.6 1.6 2.4 0.08 0.051
Tensas71357 0.043 0.1 0.045 E*2 2.5 2.5 3.5 0.16 0.108
271366 0.04 0.095 0.043 E* 2.5 2.5 3.5 0.15 0.100
71375 0.039 0.091 0.042 E* 2.5 2.5 3.5 0.15 0.098
Terrebonne70397 0.022 0.049 0.024 E*2 2.5 2.5 3.5 0.08 0.055
170356 0.024 0.053 0.025 E* 2.5 2.5 3.5 0.09 0.060
70344 0.023 0.049 0.024 E* 2.5 2.5 3.5 0.08 0.058
Union71277 0.054 0.127 0.051 C 1.2 1.2 1.7 0.09 0.065
171260 0.055 0.13 0.053 C 1.2 1.2 1.7 0.09 0.066
71234 0.048 0.113 0.048 C 1.2 1.2 1.7 0.08 0.058
Vermilion70548 0.025 0.056 0.026 E*2 2.5 2.5 3.5 0.09 0.063
170510 0.025 0.056 0.026 E* 2.5 2.5 3.5 0.09 0.063
70548 0.025 0.056 0.026 E* 2.5 2.5 3.5 0.09 0.063
Vernon71446 0.032 0.071 0.032 C 1.2 1.2 1.7 0.05 0.038
170656 0.03 0.068 0.031 C 1.2 1.2 1.7 0.05 0.036
71403 0.033 0.073 0.033 C 1.2 1.2 1.7 0.06 0.040
Washington70438 0.032 0.072 0.034 D 1.6 1.6 2.4 0.08 0.051
170427 0.032 0.071 0.033 D 1.6 1.6 2.4 0.08 0.051
70426 0.033 0.074 0.035 D 1.6 1.6 2.4 0.08 0.053
2011 Louisiana Transportation Conference
Parish Zip code PGA Ss Sl
Site Class FPGA Fa Fv SD1=Fv*Sl As=FPGA*PGA Zone
Webster71072 0.047 0.109 0.046 D 1.6 1.6 2.4 0.11 0.075
171073 0.042 0.097 0.043 D 1.6 1.6 2.4 0.10 0.067
Webster 71055 0.043 0.1 0.044 D 1.6 1.6 2.4 0.11 0.069 1
West Baton Rouge
70767 0.03 0.067 0.031 E*2 2.5 2.5 3.5 0.11 0.075 1
West Carroll
71263 0.059 0.14 0.056 E 2.5 2.5 3.5 0.20 0.148
271266 0.054 0.128 0.053 E 2.5 2.5 3.5 0.19 0.135
71237 0.052 0.124 0.051 E 2.5 2.5 3.5 0.18 0.130
West Feliciana
70775 0.031 0.071 0.033 D 1.6 1.6 2.4 0.08 0.050 1
Winn
71422 0.039 0.092 0.041 C 1.2 1.2 1.7 0.07 0.047
171473 0.04 0.093 0.042 C 1.2 1.2 1.7 0.07 0.048
71483 0.038 0.088 0.039 C 1.2 1.2 1.7 0.07 0.046
2011 Louisiana Transportation Conference
The following Parishes are designated Seismic Zone 2:
East Carroll FranklinMadisonMorehouseRichlandTensasWest Carroll
All bridges located in these parishes shall be designed using the provisions under Extreme I.
2011 Louisiana Transportation Conference
Seismic Zone Classification Map
2011 Louisiana Transportation Conference
Summary:
The structural analysis and design for theearthquake loads are specified in LRFDspecification as for four seismic zones, i.e.seismic zone 1, zone 2, zone 3 and zone 4.
Bridges in LA State shall be designed forseismic zone 1 and zone 2.
2011 Louisiana Transportation Conference
Summary:
LA Bridges in seismic zone 1 need not beanalyzed for seismic loads , regardless of theiroperational classification and geometry exceptfor the minimum requirements as specified inArticles 3.10.9 and A4.7.4.4.
2011 Louisiana Transportation Conference
Summary:
Bridges in Seismic Zone 2 shall be analyzedand designed in accordance with theminimum requirements specified in LRFDdesign specification, and the latest versionof “AASHTO guide specifications for LRFDseismic bridge design”
2011 Louisiana Transportation Conference
Summary:
The structural analysis and structural design,respectively, shall be taken into consideration forbridges located in seismic zone 2.
Bridges shall be analyzed and designed inaccordance with the minimum requirementsspecified in LRFD design specification, and thelatest version of “AASHTO guide specificationsfor LRFD seismic bridge design”
2011 Louisiana Transportation Conference
Summary:
The SEISMIC design requirements of Article 5.10.11.4 (for Seismic Zones 3 and 4) shall be taken to apply to bridges in Seismic Zone 2 except that the area of longitudinal reinforcement shall not be less than 0.01 or more than 0.06 times the gross cross-section area, Ag.
2011 Louisiana Transportation Conference
Table 4.7.4.3.1-1—Minimum Analysis Requirements for Seismic Effects
Seismic Zone
Single-Span
Bridges
Multispan BridgesOther Bridges Essential Bridges Critical Bridges
regular irregular regular irregular regular irregular1 No seismic
analysis required
* * * * * *
2 SM/UL SM SM/UL MM MM MM
* = no seismic analysis required UL = uniform load elastic methodSM = single-mode elastic method MM = multimode elastic method
Regularity is a function of the number of spans and the distribution of weight and stiffness.
Regular bridges have less than seven spans; no abrupt or unusualchanges in weight, stiffness, or geometry; and no large changes in these parameters from span to span or support-to-support.
2011 Louisiana Transportation Conference
In general, the upper boundary for Zone 2 in the current edition is significantly higher than in the previous edition due to the increase in the return period for the design earthquake.
2011 Louisiana Transportation Conference
Thank You