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OCR for page 39
39 Two-Cell CIP Dead Load: Midspan Outside Shear (kips) Midspan Outside Corner Stress (ksi) 1.14 0.945 0.94 1.12 0.935 1.1 0.93 Curve/Grid Curve/Grid 0.925 1.08 0.92 1.06 0.915 0.91 1.04 0.905 1.02 0.9 200 400 600 800 1000 Straight 200 400 600 800 1000 Straight Radius (ft) Radius (ft) a) Midspan Outside Girder Shear Ratio b) Longitudinal Stress Ratio Figure 4-14. Line graphs of shear and stress ratios of results from spine and grillage models. symmetrical. Therefore, the diaphragms were shown to have results from spine to grillage models. It was found that, in very little effect on the global response of the bridge. general, magnitudes of curve to straight results are in the same order as the integral bridges. Therefore, the final con- clusion is that, as long as the support conditions are modeled Bearings at the Bents correctly, the same guidelines for modeling limitations are The purpose of this study was to determine if bridges with equally applicable to integral and non-integral conditions. integral and non-integral bents respond differently to curve effects. All three-span five-cell spine and grillage bridge mod- Skewed Abutments els used in the parametric study were also modified to have a point bearing support at the piers; i.e., free to move in trans- A two-cell single-span (200 ft long) and a two-cell three-span verse or longitudinal directions. The results were studied bridge (200ft-300ft-200ft) were modified to have 30-degree using scatter-grams and ratio (line) diagrams comparing the skew support at the left support and another case with 30-degree All 3-Span Vr /Vs Dead Load CIP1_6x18_sp3l_dl 1.18 CIP1_6x18_sp3m_dl CIP1_6x18_sp3s_dl CIP1_6x6_sp3l_dl 1.16 CIP1_6x6_sp3m_dl CIP1_6x6_sp3s_dl 1.14 PC1_6x18_sp3l_dl PC1_6x18_sp3m_dl 1.12 PC1_6x18_sp3s_dl PC1_6x6_sp3l_dl 1.1 PC1_6x6_sp3m_dl Vr/Vs PC1_6x6_sp3s_dl 1.08 CIP2_6x18_sp3l_dl CIP2_6x18_sp3m_dl CIP2_6x18_sp3s_dl 1.06 CIP2_7x7_sp3l_dl CIP2_7x7_sp3m_dl 1.04 CIP2_7x7_sp3s_dl CIP5_6x18_sp3l_dl 1.02 CIP5_6x18_sp3m_dl CIP5_6x18_sp3s_dl 1 CIP5_8x8_sp3l_dl 0 0.5 1 1.5 2 CIP5_8x8_sp3m_dl Length/Radius (L/R) CIP5_8x8_sp3s_dl Figure 4-15. Ratio of outside web dead load shear forces in curved (Vr) to straight (Vs ) bridges where length equals middle span length.

OCR for page 39
40 All 3-Span Vline /Vgrid Dead Load Total CIP1_6x18_sp3l_dl CIP1_6x18_sp3m_dl CIP1_6x18_sp3s_dl 1.08 CIP1_6x6_sp3l_dl CIP1_6x6_sp3m_dl 1.06 CIP1_6x6_sp3s_dl PC1_6x18_sp3l_dl 1.04 PC1_6x18_sp3m_dl PC1_6x18_sp3s_dl 1.02 PC1_6x6_sp3l_dl PC1_6x6_sp3m_dl Vline/Vgrid 1 PC1_6x6_sp3s_dl CIP2_6x18_sp3l_dl 0.98 CIP2_6x18_sp3m_dl CIP2_6x18_sp3s_dl 0.96 CIP2_7x7_sp3l_dl CIP2_7x7_sp3m_dl 0.94 CIP2_7x7_sp3s_dl CIP5_6x18_sp3l_dl 0.92 CIP5_6x18_sp3m_dl CIP5_6x18_sp3s_dl CIP5_8x8_sp3l_dl 0.9 0 0.5 1 1.5 2 CIP5_8x8_sp3m_dl CIP5_8x8_sp3s_dl Length/Radius (L/R) Figure 4-16. Ratio of outside web dead load shear forces from spine to grillage model. CIP1_6x18_sp3l_dl All 3-Span fr /fsDead Load CIP1_6x18_sp3m_dl 1.1 CIP1_6x18_sp3s_dl CIP1_6x6_sp3l_dl CIP1_6x6_sp3m_dl 1.08 CIP1_6x6_sp3s_dl PC1_6x18_sp3l_dl PC1_6x18_sp3m_dl 1.06 PC1_6x18_sp3s_dl PC1_6x6_sp3l_dl PC1_6x6_sp3m_dl 1.04 PC1_6x6_sp3s_dl fr/fs CIP2_6x18_sp3l_dl 1.02 CIP2_6x18_sp3m_dl CIP2_6x18_sp3s_dl CIP2_7x7_sp3l_dl 1 CIP2_7x7_sp3m_dl CIP2_7x7_sp3s_dl CIP5_6x18_sp3l_dl 0.98 CIP5_6x18_sp3m_dl CIP5_6x18_sp3s_dl CIP5_8x8_sp3l_dl 0.96 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 CIP5_8x8_sp3m_dl Length/Radius (L/R) CIP5_8x8_sp3s_dl Figure 4-17. Ratio of outside corner dead load longitudinal stress in curved to straight bridge.