Issue 29

W. Guodong, Frattura ed Integrità Strutturale, 29 (2014) 376-384; DOI: 10.3221/IGF-ESIS.29.33 379 s s sc s bse b se s bse b y y y y y 0 M C C K K         (13) Through substituting (12) into (13), virtual absolute displacement s y  is obtained. According to pseudo excitation method, the power spectrum matrix of absolute displacement is: s s m * y y s s j 1 ( ) y y T S       (14) T HE ANALYSIS AND RESEARCH FOR CASES The Exposition of Main Information about Cases e take a prestressed concrete cable-stayed bridge with two span, single tower and double cable planes as an example whose length is 130 m, span arrangement is 75 + 55 m. Its tower pier beam is semi-consolidated structural system. The girder section is the section of double solid girder cantilever, the center height of girder is 1.9 m, roof width is 38 m, cantilever length is 4.5 m, lateral solid beam of girder is 3 m, the width of lateral solid beam across back is 4 m, the thickness of roof between solid beam is 0.28 m. The girder section across back is added with baseplate as construction due to needing balance weight, thus box cross-section forms. The girder adopts two-way prestressed system, the king-tower is reinforced concrete leaning tower, the included angle between the center line of the tower and horizon is 75°, the vertical height above bridge is 50.7 m, the king-tower adopts the filled rectangle of variable cross-section, cross section height along the bridge changes from 3 m (tower top) into 8 m (the root of tower above bridge): The width across bridge is 2.5 m. The model is constructed through general finite element software ANSYS, main girder and main tower adopt C50 concrete, stayed-cable adopts high tensile steel wire PSEM7 - 241, cross section type of girder is simulated with finite element modeling, as it is shown in Fig. 1, calculation model performs dispersing to tower with space beam element -beam 4, the girder is simplified as fishbone shape through applying spatial beam- element beam 4 with rigid arm, stayed- cable adopts link 10 units, the left end of bridge is given vertical translational constraint of freedom degree, the right end of bridge is given transverse translational constraint of freedom degree, the bottom of cable support tower is completely constrained, cable element and beam element apply hinge constraint, as it is shown in Fig. 2. Figure 1 : The girder’s sectional view of cable-stayed bridge (unit: m). Figure 2 The diagrammatic figure of concrete deck cable stayed bridge. W