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From page 141... ... NCHRP Project 12-103 141 6 Pre-Stressed Concrete Multi-Girder Bridges This section presents the tolerable support movement results obtained from the analysis of PS bridges. To structure the results, data sets were segmented by (a) Read the entire page →
From page 142... ... NCHRP Project 12-103 142 Figure 6-1 - Probability distribution for the ratio of FE-to-SLG Rating factor. 6.1.2 Load Distribution in Highly Skewed Bridges For the dead and live load distributions within highly skewed bridges, this mechanism is similar between PS concrete and steel bridges (see Section 5.1.2) Read the entire page →
From page 143... ... NCHRP Project 12-103 143 6.1.3 Uncoupling of Stiffness and Strength in Pre-Stressed Concrete Bridges As illustrated by the results in the following sections, in many cases higher levels of tolerable support movement (governed by flexural limit states) were associated with larger girder spacing for PS concrete bridges. Read the entire page →
From page 144... ... NCHRP Project 12-103 144 LD and TD movements. As with the analysis of the results for steel bridges, stepwise linear regression was employed as an exploratory tool to determine a subset of predictor variables (bridge configuration parameters) Read the entire page →
From page 145... ... NCHRP Project 12-103 145 stress limits) the superstructure tolerance to TD support movement. Read the entire page →
From page 146... ... NCHRP Project 12-103 146 criterion for simple-span bridges (0.008L) is shown in this figure as a point of comparison. Read the entire page →
From page 147... ... NCHRP Project 12-103 147 Figure 6-5 gives the plot of girder spacing versus tolerable TD support movement. The plot shows a positive trend for tolerances as girder spacing increases, indicating that girder spacing may be a more appropriate explanatory variable for estimating the level of tolerable support movement for simple-span PS concrete bridges. Read the entire page →
From page 148... ... NCHRP Project 12-103 148 Figure 6-6 - Effects plot for tolerance to TD movements occurring at the abutment of a simply supported PS concrete multigirder bridge. 6.3.2 Service Tolerance to TD Movements Figure 6-7 shows that that Service limit state (Service I or III) Read the entire page →
From page 149... ... NCHRP Project 12-103 149 Figure 6-7 - Controlling location of Service tolerance to a TD support movement occurring at the abutment of a simply supported PS concrete multi-girder bridge. Figure 6-8 - TD movement moment diagram for a highly skewed simply supported bridge. Read the entire page →
From page 150... ... NCHRP Project 12-103 150 Figure 6-9 – Service tolerance to a TD support movement as a function of span length occurring at the abutment of a simply supported PS concrete multi-girder bridge. Figure 6-10 – Service tolerance to a TD support movement as a function of skew occurring at the abutment of a simply supported PS concrete multi-girder bridge. Read the entire page →
From page 151... ... NCHRP Project 12-103 151 Figure 6-11 - Effects plot for tolerance to TD movements occurring at the abutment of a simply supported PS concrete multigirder bridge. The effects plot given by Figure 6-11 above indicates that skew is the most influential parameter. Read the entire page →
From page 152... ... NCHRP Project 12-103 152 Figure 6-12 - Interaction plot of skew and span length. Evident in Figure 6-13, as skew increases, tolerance to TD movement decreases. Read the entire page →
From page 153... ... NCHRP Project 12-103 153 6.4 Two-Span Continuous Pre-Stressed Concrete Bridges 6.4.1 Controlling Limit State The figures in this section present the controlling limit states for each type/location of support movement. For LD and TD movements occurring at the abutment, the Strength I Flexure and Shear limit states generally controlled tolerance. Read the entire page →
From page 154... ... NCHRP Project 12-103 154 Figure 6-15 - Controlling limit state for a TD support movement occurring at the abutment of a two-span continuous PS concrete multi-girder bridge. Figure 6-16 - Controlling limit state for a LD support movement occurring at the pier of a two-span continuous PS concrete multi-girder bridge. Read the entire page →
From page 155... ... NCHRP Project 12-103 155 Figure 6-17 - Controlling limit state for a TD support movement occurring at the pier of a two-span continuous PS concrete multi-girder bridge. 6.4.2 Service Tolerance to LD Movements Occurring at the Abutment The Service limit states controlled the tolerable LD support movement at the abutment in approximately 3% of the population (see Figure 6-14) Read the entire page →
From page 156... ... NCHRP Project 12-103 156 Figure 6-18 – Service tolerance to a LD support movement as a function of span length occurring at the abutment of a twospan continuous PS concrete multi-girder bridge. Figure 6-19 - Effects plot for tolerance to LD movements occurring at the abutment of a two-span continuous PS concrete multi-girder bridge. Read the entire page →
From page 157... ... NCHRP Project 12-103 157 state, a considerable number of bridges have high Strength I Flexure tolerance to LD movements occurring at the abutment. Again, the current AASHTO LRFD criterion gives a conservative estimate of tolerance for nearly the entire population. Read the entire page →
From page 158... ... NCHRP Project 12-103 158 Figure 6-21 - Effects plot for tolerance to LD movements occurring at the abutment of a two-span continuous PS concrete multi-girder bridge. 6.4.4 Strength I Shear Tolerance to LD Movements Occurring at the Abutment The Strength I Shear limit state controlled the tolerable LD support movement at the abutment for approximately 40% of the population (see Figure 6-14) Read the entire page →
From page 159... ... NCHRP Project 12-103 159 Figure 6-22 - Controlling location of Strength I Shear tolerance to a LD support movement occurring at the abutment of a two-span continuous PS concrete multi-girder bridge. Figure 6-23 gives the plot of span length versus tolerable LD support movement based on the Strength I Shear limit state. Read the entire page →
From page 160... ... NCHRP Project 12-103 160 Figure 6-24 – Strength I Shear tolerance to a LD support movement as a function of skew occurring at the abutment of a twospan continuous PS concrete multi-girder bridge. Span length (L) Read the entire page →
From page 161... ... NCHRP Project 12-103 161 The following interaction plots describe the interactions between span length/girder spacing (Figure 6-26) and span length/skew (Figure 6-27) Read the entire page →
From page 162... ... NCHRP Project 12-103 162 Figure 6-27 - Interaction plot of span length and skew. 6.4.5 Service Tolerance to TD Movements Occurring at the Abutment The Service I and III limit states controlled the tolerable TD support movement for approximately 21% of the population (see Figure 6-15) Read the entire page →
From page 163... ... NCHRP Project 12-103 163 Figure 6-28 - Controlling location of Service tolerance to a TD support movement occurring at the abutment of a two-span continuous PS concrete multi-girder bridge. Figure 6-29 gives the plot of span length versus tolerable TD support movement based on the Service limit states. Read the entire page →
From page 164... ... NCHRP Project 12-103 164 Figure 6-29 – Service tolerance to a TD support movement as a function of span length occurring at the abutment of a twospan continuous PS concrete multi-girder bridge. Figure 6-30 – Service tolerance to a TD support movement as a function of skew occurring at the abutment of a two-span continuous PS concrete multi-girder bridge.0 Span length (L) Read the entire page →
From page 165... ... NCHRP Project 12-103 165 increasing span length, girder spacing, and width, while lower tolerance is associated with increasing skew. Figure 6-31 - Effects plot for tolerance to TD movements occurring at the abutment of a two-span continuous PS concrete multi-girder bridge. Read the entire page →
From page 166... ... NCHRP Project 12-103 166 Figure 6-32 - Interaction plot for span length and girder spacing. Similar behavior exists for the interaction of skew and span length. Read the entire page →
From page 167... ... NCHRP Project 12-103 167 6.4.6 Strength I Flexure Tolerance to TD Movements Occurring at the Abutment The Strength I Flexure limit state controlled the tolerance to TD support movement for only 9% of the population (see Figure 6-15) Read the entire page →
From page 168... ... NCHRP Project 12-103 168 Figure 6-35 - Effects plot for tolerance to TD movements occurring at the abutment of a two-span continuous PS concrete multi-girder bridge. 6.4.7 Strength I Shear Tolerance to TD Movements Occurring at the Abutment The Strength I Shear limit state controlled the TD support movement at an abutment for approximately 70% of the population (see Figure 6-15) Read the entire page →
From page 169... ... NCHRP Project 12-103 169 Figure 6-36 - Controlling location of Strength I Shear tolerance to a TD support movement occurring at the abutment of a two-span continuous PS concrete multi-girder bridge. Figure 6-37 Strength I Shear tolerance to a TD support movement as a function of span length occurring at the abutment of a two-span continuous PS concrete multi-girder bridge. Read the entire page →
From page 170... ... NCHRP Project 12-103 170 Figure 6-38 – Strength I Shear tolerance to a TD support movement as a function of girder spacing occurring at the abutment of a two-span continuous PS concrete multi-girder bridge. Linear regression analysis identified girder spacing (S) Read the entire page →
From page 171... ... NCHRP Project 12-103 171 6.4.8 Service Tolerance to LD Movements Occurring at the Pier The Service III limit state controlled tolerance to LD movements occurring at the pier for nearly the entire population (see Figure 6-16) Read the entire page →
From page 172... ... NCHRP Project 12-103 172 Figure 6-41 – Strength I Flexure tolerance to a LD support movement as a function of span length occurring at the pier of a two-span continuous PS concrete multi-girder bridge. 6.4.10 Strength I Shear Tolerance to LD Movements Occurring at the Pier The Strength I Shear limit state controlled the tolerable LD support movement at the pier for a single bridge (see Figure 6-16) Read the entire page →
From page 173... ... NCHRP Project 12-103 173 Figure 6-42 – Strength I Shear tolerance to a LD support movement as a function of span length occurring at the pier of a two-span continuous PS concrete multi-girder bridge. 6.4.11 Service Tolerance to TD Movements Occurring at the Pier The Service III limit state controlled the tolerable TD support movement at the pier for 88% of the population (see Figure 6-17) Read the entire page →
From page 174... ... NCHRP Project 12-103 174 Figure 6-43 – Service tolerance to a TD support movement as a function of span length occurring at the pier of a two-span continuous PS concrete multi-girder bridge. 6.4.12 Strength I Flexure Tolerance to TD Movements Occurring at the Pier The Strength I Flexure limit state never controlled the tolerable TD support movement at the pier (see Figure 6-17) Read the entire page →
From page 175... ... NCHRP Project 12-103 175 6.4.13 Strength I Shear Tolerance to TD Movements Occurring at the Pier The Strength I Shear limit state controlled the tolerable TD support movements at the pier for 12% of the population (see Figure 6-17) Read the entire page →
From page 176... ... NCHRP Project 12-103 176 Figure 6-46 - Controlling limit state for a LD support movement occurring at the abutment of a three-span continuous PS concrete multi-girder bridge. Figure 6-47 - Controlling limit state for a TD support movement occurring at the abutment of a three-span continuous PS concrete multi-girder bridge. Read the entire page →
From page 177... ... NCHRP Project 12-103 177 Figure 6-48 - Controlling limit state for a LD support movement occurring at the pier of a three-span continuous PS concrete multi-girder bridge. Figure 6-49 - Controlling limit state for a TD support movement occurring at the pier of a three-span continuous PS concrete multi-girder bridge. Read the entire page →
From page 178... ... NCHRP Project 12-103 178 6.5.2 Service Tolerance to LD Movements Occurring at the Abutment The Service limit states controlled the tolerable LD support movement at the abutment for 54% of the population (see Figure 6-46) Read the entire page →
From page 179... ... NCHRP Project 12-103 179 Figure 6-51 - Effects plot for tolerance to LD movements occurring at the abutment of a three-span continuous PS concrete multi-girder bridge. 6.5.3 Strength I Flexure Tolerance to LD Movements Occurring at the Abutment The Strength I Flexure limit state controlled the level of tolerable support movement at the abutment for approximately 26% of the population (see Figure 6-46) Read the entire page →
From page 180... ... NCHRP Project 12-103 180 Figure 6-52 – Strength I Flexure tolerance to a LD support movement occurring at the abutment of a three-span continuous PS concrete multi-girder bridge. Figure 6-53 – Strength I Flexure tolerance to a LD support movement occurring at the abutment of a three-span continuous PS concrete multi-girder bridge. Read the entire page →
From page 181... ... NCHRP Project 12-103 181 criterion (0.004l) is conservative for nearly the entire population. Read the entire page →
From page 182... ... NCHRP Project 12-103 182 Figure 6-55 – Strength I Shear tolerance to a LD support movement occurring at the abutment of a three-span continuous PS concrete multi-girder bridge. Linear regression analysis identified span length (L) Read the entire page →
From page 183... ... NCHRP Project 12-103 183 The interactions of skew and girder spacing with span length, were found to affect the Strength I Shear tolerance. Figure 6-57 gives the interaction plot of span length and girder spacing. Read the entire page →
From page 184... ... NCHRP Project 12-103 184 Figure 6-58 - Interaction plot of span length and skew. 6.5.5 Service Tolerance to TD Movements Occurring at the Abutment The Service I and III limit states controlled the tolerable TD support at the abutment for approximately 41% of the population (see Figure 6-47) Read the entire page →
From page 185... ... NCHRP Project 12-103 185 Figure 6-59 - Controlling location of Service tolerance to a TD support movement occurring at the abutment of a three-span continuous PS concrete multi-girder bridge. Figure 6-60 gives the plot of span length versus tolerable TD support movement based on the Service limit states. Read the entire page →
From page 186... ... NCHRP Project 12-103 186 6.5.6 Strength I Flexure Tolerance to TD Movements Occurring at the Abutment The Strength I Flexure limit state controlled tolerable TD support movement at the abutment for 14% of the population (see Figure 6-47) Read the entire page →
From page 187... ... NCHRP Project 12-103 187 Figure 6-62 - Controlling location of Strength I Shear tolerance to a TD support movement occurring at the abutment of a three-span continuous PS concrete multi-girder bridge. Figure 6-63 gives the plot of span length versus tolerable TD support movement based on the Strength I Shear limit state. Read the entire page →
From page 188... ... NCHRP Project 12-103 188 Figure 6-63 – Strength I Shear tolerance to a TD support movement occurring at the abutment of a three-span continuous PS concrete multi-girder bridge. Figure 6-64 – Strength I Shear tolerance to a TD support movement occurring at the abutment of a three-span continuous PS concrete multi-girder bridge. Read the entire page →
From page 189... ... NCHRP Project 12-103 189 Figure 6-65 - Effects plot for tolerance to TD movements occurring at the abutment of a three-span continuous PS concrete multi-girder bridge. 6.5.8 Service Tolerance to LD Movements Occurring at the Pier The Service III limit state controlled the tolerable LD support movement at the pier for the entire population (see Figure 6-48) Read the entire page →
From page 190... ... NCHRP Project 12-103 190 Figure 6-66 – Service tolerance to a LD support movement occurring at the pier of a three-span continuous PS concrete multigirder bridge. 6.5.9 Strength I Flexure Tolerance to LD Movements Occurring at the Pier The Strength I Flexure limit state never controlled the tolerable LD support movement at the pier (see Figure 6-48) Read the entire page →
From page 191... ... NCHRP Project 12-103 191 Figure 6-67 – Strength I Flexure tolerance to a LD support movement occurring at the pier of a three-span continuous PS concrete multi-girder bridge. 6.5.10 Strength I Shear Tolerance to LD Movements Occurring at the Pier The Strength I Shear limit state never controlled the tolerable LD support movement at the pier (see Figure 6-48) Read the entire page →
From page 192... ... NCHRP Project 12-103 192 Figure 6-68 – Strength I Shear tolerance to a LD support movement occurring at the pier of a three-span continuous PS concrete multi-girder bridge. 6.5.11 Service Tolerance to TD Movements Occurring at the Pier The Service III limit state controlled the tolerable TD support movement at the pier for 91% of the population (see Figure 6-49) Read the entire page →
From page 193... ... NCHRP Project 12-103 193 Figure 6-69 – Service tolerance to a TD support movement occurring at the pier of a three-span continuous PS concrete multigirder bridge. 6.5.12 Strength I Flexure Tolerance to TD Movements Occurring at the Pier The Strength I Flexure limit state never controlled the TD support movement at the pier (see Figure 6-49) Read the entire page →
From page 194... ... NCHRP Project 12-103 194 Figure 6-70 – Strength I Flexure tolerance to a TD support movement occurring at the pier of a three-span continuous PS concrete multi-girder bridge. 6.5.13 Strength I Shear Tolerance to TD Movements Occurring at the Pier The Strength I Shear limit state controlled the tolerable TD support movement at the pier for 9% of the population (see Figure 6-49) Read the entire page →
From page 195... ... NCHRP Project 12-103 195 Figure 6-71 – Strength I Shear tolerance to a TD support movement occurring at the pier of a three-span continuous PS concrete multi-girder bridge. 6.6 Summary of Results As discussed in Section 5 and throughout this section, the parameters that influence superstructure tolerance to support movements will vary depending on the type and location of support movement. Read the entire page →
From page 196... ... NCHRP Project 12-103 196 Strength I Shear and Service III limit states. This is evident in Table 6-3 that shows that current AASHTO guidance is unconservative for a considerably large number of bridges. Read the entire page →
From page 197... ... NCHRP Project 12-103 197 of skewed bridges Service I & III 10% - LD Support Movement at Pier Strength I Flexure 31% Due to increase in positive moment in positive moment region Strength I Shear 10% - Service I & III 100% Due to the lack of additional capacity for the Service III limit state TD Support Movement at Pier* Strength I Flexure 28% Due to increase in positive moment in positive moment region Strength I Shear 56% Due to inability of SLG model to properly account for dead load distribution of skewed bridges Service I & III 100% Due to the lack of additional capacity for the Service III limit state Three-Span Continuous LD Support Movement at Abutment Strength I Flexure 2.5% - Strength I Shear 0% - Service I & III 0% - TD Support Movement at Abutment* Read the entire page →
From page 198... ... NCHRP Project 12-103 198 Service I & III 10% - LD Support Movement at Pier Strength I Flexure 31% Due to increase in positive moment in positive moment region Strength I Shear 10% - Service I & III 100% Due to the lack of additional capacity for the Service III limit state TD Support Movement at Pier* Strength I Flexure 28% Due to increase in positive moment in positive moment region Strength I Shear 56% Due to inability of SLG model to properly account for dead load distribution of skewed bridges Service I & III 100% Due to the lack of additional capacity for the Service III limit state * Read the entire page →
From page 199... ... NCHRP Project 12-103 199 Service III will control tolerance for most prestressed concrete bridges, however a designer may wish to allow a service limit state to be exceeded. For this reason, a separate expression was developed. Read the entire page →
From page 200... ... NCHRP Project 12-103 200 Figure 6-72 – Scatter plot of tolerance for the Service III limit state with the expression developed for estimating maximum tolerable support movement. Read the entire page →
From page 201... ... NCHRP Project 12-103 201 Figure 6-73 – Scatter plot of tolerance for Strength I limit states with the expression developed for estimating maximum tolerable support movement. Read the entire page →

From page 141...

... NCHRP Project 12-103 141 6 Pre-Stressed Concrete Multi-Girder Bridges This section presents the tolerable support movement results obtained from the analysis of PS bridges. To structure the results, data sets were segmented by (a)