- Carriageway position: deck bridge
- Stress of load-bearing components: beam bridge
Content introduction 1. Design standards and specifications 1. Technical Standards for Highway Engineering (JTJ001 － 97) issued by the Ministry of Communications of the People's Republic of China. 2. Standard issued by the Ministry of Communications of the People's Republic of China General Code for Design of Highway Bridges and Culverts (JTJ021-89). 3. Standard issued by the Ministry of Communications of the People's Republic of China, Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts (JTJ023-85). 2、 Technical standard 1. Design load: automobile - level 20; Trailer - 120 2. Deck clearance: net 13.5+2 × 0.5m anti-collision retaining wall (or anti-collision retaining wall) (single width) 3. Span: 28~31m 3. Main materials: 1. Concrete: 50 # concrete for precast T-shaped beam and cast-in-place bridge deck; 25 # concrete for cast-in-place anti-collision parapet; 50 # concrete is used for cast-in-situ beam at expansion joint end and cast-in-situ continuous section at pier top; Asphalt concrete is used for bridge deck pavement. 2. Prestressed steel strand: American standard ASTMA416-87a270 high strength low relaxation prestressed steel strand is adopted. Nominal diameter 15.24mm, nominal area 140mm2, standard strength Rby=1860Mpa, elastic modulus E=1.95 × 105 Mpa. 3. The anchorage used shall meet the design requirements and comply with the provisions of 12.3 in Chapter 12 of the Technical Code for Construction of Highway Bridges and Culverts (JTJ041-2000). Prestressed pipes and materials shall comply with the provisions of 12.4 in Chapter 12 of the Technical Code for Construction of Highway Bridges and Culverts (JTJ014-2000). 4. Ordinary reinforcement shall be grade I and II reinforcement. 5. Steel plate: ordinary carbon structural steel in accordance with GB/T700-88. 6. Plate rubber bearing is adopted. GYZF4 (φ 400 × 88mm) polytetrafluoroethylene sliding plate rubber bearings shall be selected for the corresponding bearings at both ends of the abutment and each link (i.e. the expansion joint), and GYZ (φ 400 × 77mm) plate rubber bearings shall be selected for the rest. 7. The continuous structure of 1~2 holes and one connected bridge deck adopts CD-60 expansion joint; FD-80 expansion joint is adopted for the continuous structure of 3~4 holes and one connected bridge deck; The continuous structure of 5-7 hole single deck adopts QMSF-160 expansion joint. See the design specification of the bridge for special conditions. 4、 Structure and design points 1. Main beam spacing: 2.15m. 2. Number of main beams: 7 pieces per hole. 3. Main beam height: 1.85m. 4. When the radius of horizontal curve is greater than or equal to 400m, there are at most 7 holes in each joint; When the radius of horizontal curve is greater than or equal to 300m and less than 400m, the maximum number of holes in each joint is 5. 5. Distance from the center of the support to the center line of the pier: 0.59m6. Prefabricated T-shaped beams are designed with three end forms, and three T-shaped beams A-shaped T-beams are formed after combination: simply supported T-beams at both ends; Type B T-beam: a simply supported and continuous T-beam at one end; C-type T beam: continuous T beam at both ends; In order to simplify the formwork and facilitate the construction, the width of the prefabricated T-shaped beam rib shall be 20cm, the width of the horseshoe shall be 42cm, and the width of the end beam rib shall be widened to the same width as the horseshoe. In the middle of the bridge span formed in the radial direction of the road centerline, the curved bridge is formed by precast T-beam flange plate and cast-in-place bridge deck. Each hole of the bridge is provided with three middle diaphragms, two end diaphragms, and the middle diaphragms are orthogonal to the main beam. End diaphragms are set radially. Due to the different inclination angles at both ends of the main beam of each bridge, the design will place the central diaphragm at half of the shortest beam of this bridge, and then determine the spacing LAi and LBi of the diaphragm of the other beams. 7. The cross section of bridge main beam is composed of precast T-shaped beam, cast-in-place bridge deck, end diaphragm and middle diaphragm. The rigid plate beam method is used for horizontal calculation. The top transverse slope of precast T-shaped beam is the average of the transverse slopes at both ends of each hole. The bottom cross slope of the middle diaphragm and end diaphragm is consistent with the beam top cross slope. The cross slope of the bridge deck is adjusted by the capping beam and the bearing pad stone. In order to make the bearing set horizontally, beam shoes meeting the longitudinal slope of the main beam are set at both ends of the prefabricated T-beam. 8. In this drawing, precast T-shaped beam is placed on the cap beam, and the simple support system is converted to continuous system. The maximum span is designed as seven spans and one joint. 9. The prestressed design of the main beam adopts fully prestressed concrete in load combination I (automobile+dead load), and other load combinations are calculated as partially prestressed concrete Class A members. The first stage dead load is calculated as a simply supported static structure, and the second stage dead load and variable load or accidental load combination is calculated as a continuous beam system. Layout of Prestressed Tendon Positioning Reinforcement Mesh of Pier Top Deck Reinforcement Layout of Bridge Deck Prestressed Tendon Layout of Mid span Pier Top Deck
