Design studies of the Castle Bridge over Wislok River in Rzeszow with application of CAD System

Transcription

1 Design studies of the Castle Bridge over Wislok River in Rzeszow with application of CAD System Author: Dariusz Alterman Superviser: Dr. Tomasz Siwowski, Civ. Eng. Chairman of the examination committee: Prof. Andrzej Jarominiak Technical University of Rzeszow, Poland Faculty of Civil Engineering Institute of Bridges Beginning of the study: April 1999 End of the study: June 2000 Presentation and final examination: July 5, 2000 Final evaluation: very good (the highest note) Contents: 1. Scope of the project 2. Location of the bridge and the transportation system 3. Main characteristics of the road on the bridge 4. Requirements concerning the environmental area 5. Research on the main structure of the bridge 6. Description of the selected solution of the bridge structure 7. Description of the piers and abutments 8. Technology of the erection of the bridge 9. Standard loads on the bridge 10. Computation of the main structure of the bridge 11. Verification of strength of the girders 12. Additional remarks and final conclusions References Computer programs used Acknowledgments Abstract In the paper the research is presented aimed at design of the stayed bridge over Wislok River in Rzeszow. The research covered various aspects of the bridge: its aesthetics and architecture in the historical part of the town, structure and safety, technology of execution, overall cost, etc. The research was based on local data and the final design was submitted to the Urban Development Office for consideration as one of possible solutions and as a reference for further analysis. The author s present address: Institute of Fundamental Technological Research, Polish Academy of Sciences, Swietokrzyska 21, Warsaw, Poland Rzeszow 2000

2 1. Scope of the project The subject of the final project for a degree of Master of Civil Engineering was a design of the Castle Bridge over the Wislok River in Rzeszow located between the existing streets and parks. All data concerning road and transport system, location of the bridge, quality of the soils, characteristic of the river and the cross-section of the road are based on the requirements and specifications obtained from the Urban Development Office (UDO) in Rzeszow. The aim of the project was to prepare a preliminary design of the cable-stayed bridge. Initial stage of the designing had to cover several solutions, prepared previously by the students and in the design offices. Finally, the project comprised the following operations: - Collection and analysis of all available proposals concerning the Castle Bridge; - Preparation of the photographic documentation of the bridge surroundings; - Preparation of basic data for designing; - Architectural studies of a cable-stayed bridge concerning the forms of pylon, intermediate piers and abutments, as well as selection of the final solution; - Static analysis and verification of the strength of main structural elements taking into account also erection stages; - Design of the bridge deck; - Description of all main elements and structural materials of the bridge; Complete design with detailing of the bridge and of the approaching spans; Architectural design of the bridge, including its presentation in perspective view; Analysis of the bridge from the aesthetical viewpoint, using photographic documentation of the surrounding area and animation technique. 2. Location of the bridge and the transportation system Fig.1 2

3 The designed new road and new bridge should fulfil several important functions: - Connection of the existing center of Rzeszow with the developing areas for habitation on the right side of the Wisłok River, (New Town side Fig.1). - Transportation of people between habitation areas and the center of the town by buses, cars and bicycles, also pedestrian traffic is accommodated. - Passage of the long distance traffic across the town. The design of the bridge and roads in the area is strongly limited by requirements due to: - Preservation of the old parts of town, including the Lubomirski s Castle; - Existing parks, gardens and sport halls; - Inundation zones at flooding; - Historical values of the existing buildings and other installations; - Status of private property of several parts of the surrounding area. 3. Main characteristics of the road on the bridge Imposed characteristics of the bridge deck cross-section are related to its function and are shown in Fig.2. Live load according to the Bridge Design Code PN-85/S-10030, Class A is adopted. Total length of the bridge is approximately 200 m m m m 3.5 m m 2.25 m 0.25 Sidewalk 2 % Safety lane 2 % Road 2 % Bike path Sidewalk 2 % 2 % Fig.2 4. Requirements concerning the environmental area On the left bank of the Wislok River there are zones with high historical value subjected to the rigorous preservation control. These are mainly the Lubomirski s Castle, old buildings in its vicinity and the town landscape. All belongs to the traditional zone of old Rzeszow of XIX century, where apart of the main transportation lanes, the road traffic should be restricted, leaving green space for the population. The zone was naturally shaped by the river, which modified its bed in the past centuries. The right bank of the river is flat. On the left bank, there are first the zones also frequently covered by floods and then higher flat plateau with the Castle. Historical and aesthetical values of the Castle should be preserved and emphasized, among others by the bridge single tall pylon. Adequate studies have shown that in the foundation zones the soil is composed of: - thin layers of 0.6m depth of cultivable soil, - river sedimentations layer 3-4m deep, with sand and gravel layers below. 5. Research of the main structure of the bridge Fig.3 3

4 In the design of the bridge seven different cable-stayed systems were considered; for the lack of space only three of them are shown in Figs.3-5. Fig.4 Fig.5 For further design and analysis the solution shown in Fig.6 was selected as the most elegant. Fig.6 The structure is composed of four-span steel girders stayed at six points and supported on three intermediate piers and two abutments. Cables are anchored on the pylon. All piers, abutments and the pylon are made of reinforced concrete. The bridge has total length of 191 m and angle between its axis and the river is equal to 90. Main criteria for selection of this system were: - Aesthetical requirements, - Values of the internal forces. In the design of the pylon itself mainly aesthetical arguments have been considered because of the neighbourhood of the Castle. Seven different solutions have been analysed that are shown in Fig. 7. Finally, the pylon of the H-shape has been selected (Fig.7g). Lower transversal beam supports the main girders and the upper beam ensures stability of the top branches where cables are anchored. 4

5 a) b) c) d) e) f) g) Fig.7 Different structural solutions of the composite steel-concrete bridge deck have been studied in detail as shown in Fig.8. Fig.8 The selected bridge deck is shown in Fig.9. It ensures acceptable aerodynamic characteristics and low weight, together with the adequate stability and strength at all stages of erection. It is made of the composite reinforced concrete slab 0.23 m deep, connected to the steel girders with welded bolts. The diaphragms are spaced by 8.00 m and cables are anchored at the edge longitudinal beams. Depth of the main girders is constant along the bridge and equal to 1.30 m. The sidewalks are covered with a layer of lightweight concrete type LB30. Fig.9 5

6 6. Description of the selected solution of the bridge The final selected solution is shown in Figs. 6, 7g and 9. Two abutments and three intermediate piers support four-span continuous welded girders made with steel 18G2A. The girders are suspended on six cables, anchored in the top of the pylon and in the edge beams of the deck. For the anchorages BBR CONA STAY CS5506 system is applied. Total length of the bridge with abutment wings is m. The abutments and piers are founded on piles. The solution was selected because of its following advantages: - Excellent architectural aspect taking into account all aesthetical requirements related to the existing historical buildings and the values of the landscape; - Tall pylon is an interesting modern accent in the landscape. - Long river span corresponds well to the recreational traffic along the banks of the river; 7. Description of the piers and abutments With respect to the soil and foundation conditions following constructions are selected: - Two reinforced concrete abutments No1 and 5, (Fig. 6), each founded on a slab 13 x 4 x 1.10 m and on large diameter piles; - Two piers No 2 and 3, composed of two columns of cross-section 1.26x1.05m, a cap beam with steel bearings and a lower slab as a capping for the piles, (Fig.10); - Pylon of m in width and of total height of 48.7m. also founded on piles. Fig.10 All piers and abutments are founded on large reinforced concrete piles φ 1.20 m. Concrete of quality B30 and reinforcing steel 18G2A are used except concrete B60 in the pylon. In both abutments special caverns 0.71 x 1.91 m are designed for revision and possible future replacements of the bridge bearings and expansion joints. Behind the abutments the approach slabs 7.40 x 3.50 m are located to ensure smooth passage between the embankment and the abutment. The embankment with the slope of 1:1.5 is reinforced with fibre mats GEOWEB. The slopes are covered with grass. On the external faces of the pylon branches the groves are designed to emphasize their slenderness. Each branch of the pylon is founded on 25 piles φ 1.20 m with a foundation slab 12.0 x 11.5 x 4.0 m. The number of the piles and other details of the bridge foundations should be verified in the final design. 8. Technology of erection of the bridge Following assumptions were accepted for the execution of the bridge: - Steel girders and diaphragrams are manufactured in a factory in the sections correlated with the available trucks. 6

7 - The girders are assembled in situ by welding and launched over the piers (Fig. 11). - The pylon is cast in climbing formwork system before the longitudinal launching of the main girders reaches the pylon itself. - The cables are installed and tensioned using BBR equipment at the final stage. Fig Standard loads on the bridge The bridge was designed according to the Polish Standard PN-85/S and the variable load on the bridge was applied as shown in Fig. 12. For the main girders and the deck the following load combinations were considered: Basic state: - own weight of the structure and permanent installations - variable load of a special vehicle K and uniformly distributed lane load q. Exceptional state: - as above and the wind action on loaded or unloaded spans. Fig Computation of the main structure of the bridge The bridge structure was computed as a three-dimensional (3D) frame using the program ROBOT V6, adequately defining virtual displacements of the selected nodes. Then, all the extreme values of internal forces and bending moments (Fig. 13) were determined in main girders and diaphragms, for various loading states. 7

8 Fig.13 The results are presented in the Table and as an example for the left main girder on the diagram in Fig. 14. Left girder Fig.14 Bending moments [knm] MAX MIN Cross section 11. Verification of strength of the main girders Verification of strength was carried out applying the limit state method, assuming elastic strain of structural materials: steel and concrete, according to the Polish Standard for Bridges PN-82/S All computations were made using MathCad 7.0 and Excel 7.0. As results, extreme values of stresses in the cross-sections were computed at appropriated points and for various loading states. Obtained values have been compared with the following admissible values: for steel 18G2A design strength f s = 295 MPa and for concrete B45 design strength f b = 26 MPa. Final results are shown in the Table for the main girders and for various elements of the bridge deck. For detailing, nine different sections of the main girder were considered, and the examples of the cross-sections of the main girders for different zones are shown in Fig.15. Fig.15 8

9 Fig.16 Fig.17 9

10 Table: verification of the stress values Structural element and cross-section stresses in steel [MPa] stresses in concrete [MPa] lower edge upper edge lower edge upper edge Composite cross-section - zone I Composite cross-section - zone II Composite cross-section - zone III Composite cross-section - zone IV Composite cross-section - zone V Composite cross-section - zone VI Composite cross-section - zone VII Composite cross-section - zone VIII Composite cross-section - zone IX Intermediary diaphragms Diaphragms at the cable Diaphragms above the supports Cantilver under the cable Cantilever above the supports Longitudinal beam at the cable line After the computation and verification of strength it is concluded that the design stress is everywhere lower than the admissible stress values: in the upper flange of the steel girder by 2 17 %, in the lower flange by 50% or more. Also design stresses in concrete B45 are lower than admissible values. 12. Additional remarks and final conclusions Beside the design of the structural elements of the bridge and their detailed analysis, the following operations have been performed to check the aesthetic values of the bridge: - Computer visualization of the selected bridge structure within the scanned landscape; - 3D modelling of the bridge and its elements with AutoCAD R14; - Modeling with 3D Studio MAX R2 for several views of the pylon, also using Photo-Paint and Microsoft Photo Editor to show the bridge in its neighbourhood. Animation of duration of appr. 100sec. showing the bridge from different observation points was also prepared, all figures were made using CorelDRAW 7.0. The final design of the bridge as shown in Figs.16 and 17 is submitted to the UDO in Rzeszow for possible studies and applications as a reference in evaluation of future projects. Humans were building bridges since always, showing not only their technical level but also their trend to beauty and perfection. At present, the bridges still express these feelings. References Computer programs used: AutoCAD R14. CorelDRAW 7.0. Mathcad 7.0 Professional. 3D Studio MAX R2. Robot V6. Microsoft Photo Editor. Photo Paint 7.0. Acknowledgements The author is grateful to Professor A. Jarominiak and Dr. T. Siwowski for their help and encouraging and to the UDO in Rzeszow for access to the technical data concerning the Castel Bridge location and neighbourhood. 10