[Yunnan] Construction Drawing of 20m Span Precast T-beam One span Bridge

Technical standard: 1. Design load: highway - Class I; 2. Design flood level frequency: 1/100; 3. Seismic peak acceleration: 0.1g; 4. Bridge layout and structural form: new 1x20m reinforced concrete prestressed T beam with a total length of 26.04m; 5. Deck width: 7.5m (carriageway)+2X0.5m (guardrail), 8.5m in full width; 6. Bridge deck cross slope: one-way 4%; 7. Deck pavement: 10cm thick C40 waterproof reinforced concrete+12cm asphalt concrete; 8. Guardrail: reinforced concrete crash barrier; 9. Expansion joint: plate type - 40 expansion joint, There are 32 CAD design drawings in total.

XX Bridge is located in XX Town, XX County, and was built in 1994. It has 4 spans, each 13 meters long, with a total length of 63.0 meters. The width of the bridge deck is 4.0 meters (carriageway)+2 × 1.0 meters (sidewalk). The upper structure is reinforced concrete hollow slab with 5 slabs per span; The substructure is gravity abutment, expanded foundation, pile column pier, with pile diameter of 1.00m, column diameter of 0.80m, transverse tie beam of 0.70m wide and 0.90m high. With the development of local economy and the increasingly close combination of urban and rural areas, the traffic volume is growing very rapidly, and there are many heavy vehicles, especially the role of overloaded vehicles. The bridge is far from meeting the requirements of bearing capacity and normal use. Many parts of the bridge's load-bearing structure were damaged due to various reasons such as construction quality, post lifting management and maintenance. The top plates of four reinforced concrete hollow slabs of the superstructure collapsed, and the longitudinal axis of the pile columns of the three piers of the substructure deviated greatly. The piles and columns were staggered in both the longitudinal and transverse directions, forming eccentricity, with an eccentricity distance of 10-25cm. The pile and column center lines are out of alignment and not parallel to each other. The pile head was not cleaned up during construction, so that the pile column joint section contains bricks, mud and sand and other sundries, resulting in necking, cavity and other defects. The side wall of the north abutment is fractured, tilted outward, and displaced. The side wall is fractured and separated from the front wall, with a crack width of 3cm and a dislocation distance of 5cm. At present, the bridge is restricted to traffic and has been designated as a dangerous bridge.

Entrusted by the traffic bureau of a certain county, it is planned to demolish the original site of the old bridge and rebuild a 3 × 20m reinforced concrete T-shaped beam bridge with a width of 6.0m for the carriageway+2 × 0.5m for the guardrail. The substructure adopts double column pier (abutment) and cast-in-place pile foundation.

Technical standards:

1. Design load: highway - Class I;

2. Design flood level frequency: 1/100;

3. Seismic peak acceleration: 0.1g;

4. Bridge layout and structural form: new 1x20m reinforced concrete prestressed T beam with a total length of 26.04m;

5. Deck width: 7.5m (carriageway)+2X0.5m (guardrail), 8.5m in full width;

6. Bridge deck cross slope: one-way 4%;

7. Deck pavement: 10cm thick C40 waterproof reinforced concrete+12cm asphalt concrete;

8. Guardrail: reinforced concrete crash barrier;

9. Expansion joint: plate type - 40 expansion joint.

XX Bridge is the longest bridge in Laoyemiao Hohhot Jining section of Dandong Lhasa National Highway trunk line Hohhot Expressway. The bridge has 12 holes and 20 meters, and its center stake is K417+200. The total length of the bridge is 240 meters. The superstructure adopts 20 meters post tensioned prestressed hollow box girder and wall guardrail; The substructure adopts column pier, the pier foundation is bored pile foundation, the ribbed abutment, and the abutment foundation is expanded foundation. (1) Box girder prefabrication The box girder prefabrication is carried out in the box girder prefabrication yard of XX Bridge. The external formwork of the hollow box girder adopts the set shaped steel formwork, and the internal formwork adopts the method of plastic cloth covering standard wood formwork to ensure the width and thickness of the box girder rib plate and top plate. Concrete vibration adopts the method of combination of attached vibration and immersion vibration to ensure the quality of concrete. Prestress tensioning: two-way tensioning process is adopted for tensioning to ensure uniform stress and friction loss of the steel strand. The tensioning sequence is in accordance with the design requirements to ensure uniform stress of the structure during the application of prestress. The initial stress of tensioning is generally 10% of the control stress. Measure the pick output of the jack, then pull it to 20%, measure the pick output, and finally pull it to the over tensioning stage, When it reaches 103% δ K, hold the load for 5 minutes, and then return to the anchor, measure the pickaxe weight, subtract two times to calculate the measured elongation value of the steel strand, the actual elongation value is equal to the sum of the measured elongation value and the calculated elongation value at the initial stress, and the calculated elongation value can be the elongation of the adjacent level. The difference between the measured elongation value and the theoretical elongation value is ± 6%. Duct grouting: 42.5 cement shall be used for grouting, and the slurry machine shall be of forced type, and have the functions of primary filtration and secondary mixing. The consistency of the clean slurry is the key to quality control. To ensure the strength of the slurry, the water cement ratio shall be small, controlled between 0.33-0.40. Adjust the consistency of the slurry by adjusting the water reducer, which is generally controlled at 14-18S. The maximum pressure of the grouting is controlled at 0.5-0.7Mpa, and there is a certain pressure stabilization time. The grouting should be until the thick slurry is fully discharged from the other end, and the slurry with the same consistency as the original slurry is discharged from all vent holes. (2) When pouring concrete of other structures to prevent the appearance of blisters and bubbles in a large area, water reducer shall be used for concrete mixing, and the construction process of bucket plus canvas tumbling barrel shall be used for pouring to effectively prevent the segregation of concrete pouring. The vibration shall be conducted with alternating frequency immersion vibrator. 　　

1、 Technical Standards and Design Specifications 1. Technical Standards for Highway Engineering JTG B01-2003 2. General Specifications for Design of Highway Bridges and Culverts JTG D60-2004 3. Design Specifications for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts JTG D62-2004 4. Technical Specifications for Construction of Highway Bridges and Culverts JTJ041-2000 5. Technical Specifications for Design of Highway Traffic Safety Facilities JTG D81-2006 IV. Key points of design 1. The structural system in this general drawing is a simple supported continuous deck structure, which is designed as a fully prestressed member. 2. The plane bar structure calculation software is used for design calculation, and the transverse distribution coefficient is calculated by rigid beam method, and checked by space structure calculation software. 3. Design parameter 1) Concrete: gravity density γ=26.0kN/, elastic modulus EC=3.45 × MPa. 2) Asphalt concrete: gravity density γ=24.0kN/. 3) Prestressed reinforcement: elastic modulus Ep=1.95 × 105 MPa, relaxation rate ρ=0.035, relaxation coefficient ζ=0.3. 4) Anchorage: anchorage deformation and rebar retraction are calculated as 6mm (one end); Metal bellows friction coefficient μ=0.25, deviation coefficient k=0.0015. 5) Uneven settlement of bearing: Δ=5mm 6) Vertical gradient temperature effect: value shall be taken according to the Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts (JTG D62-2004). 　　

1、 Technical Standards and Design Specifications 1. Technical Standards for Highway Engineering JTG B01-2003 2. General Specifications for Design of Highway Bridges and Culverts JTG D60-2004 3. Design Specifications for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts JTG D62-2004 4. Technical Specifications for Construction of Highway Bridges and Culverts JTJ041-2000 5. Technical Specifications for Design of Highway Traffic Safety Facilities JTG D81-2006 IV. Key points of design 1. The structural system in this general drawing is a simple supported continuous deck structure, which is designed as a fully prestressed member. 2. The plane bar structure calculation software is used for design calculation, and the transverse distribution coefficient is calculated by rigid beam method, and checked by space structure calculation software. 3. Design parameter 1) Concrete: gravity density γ=26.0kN/, elastic modulus EC=3.45 × MPa. 2) Asphalt concrete: gravity density γ=24.0kN/. 3) Prestressed reinforcement: elastic modulus Ep=1.95 × 105 MPa, relaxation rate ρ=0.035, relaxation coefficient ζ=0.3. 4) Anchorage: anchorage deformation and rebar retraction are calculated as 6mm (one end); Metal bellows friction coefficient μ=0.25, deviation coefficient k=0.0015. 5) Uneven settlement of bearing: Δ=5mm 6) Vertical gradient temperature effect: value shall be taken according to the Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts (JTG D62-2004). 　　

1、 Technical Standards and Design Specifications 1. Technical Standards for Highway Engineering JTG B01-2003 2. General Specifications for Design of Highway Bridges and Culverts JTG D60-2004 3. Design Specifications for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts JTG D62-2004 4. Technical Specifications for Construction of Highway Bridges and Culverts JTJ041-2000 5. Technical Specifications for Design of Highway Traffic Safety Facilities JTG D81-2006 IV. Key points of design 1. The structural system in this general drawing is a simple supported continuous deck structure, which is designed as a fully prestressed member. 2. The plane bar structure calculation software is used for design calculation, and the transverse distribution coefficient is calculated by rigid beam method, and checked by space structure calculation software. 3. Design parameter 1) Concrete: gravity density γ=26.0kN/, elastic modulus EC=3.45 × MPa. 2) Asphalt concrete: gravity density γ=24.0kN/. 3) Prestressed reinforcement: elastic modulus Ep=1.95 × 105 MPa, relaxation rate ρ=0.035, relaxation coefficient ζ=0.3. 4) Anchorage: anchorage deformation and rebar retraction are calculated as 6mm (one end); Metal bellows friction coefficient μ=0.25, deviation coefficient k=0.0015. 5) Uneven settlement of bearing: Δ=5mm 6) Vertical gradient temperature effect: value shall be taken according to the Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts (JTG D62-2004). 　　

1、 Technical Standards and Design Specifications 1. Technical Standards for Highway Engineering JTG B01-2003 2. General Specifications for Design of Highway Bridges and Culverts JTG D60-2004 3. Design Specifications for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts JTG D62-2004 4. Technical Specifications for Construction of Highway Bridges and Culverts JTJ041-2000 5. Technical Specifications for Design of Highway Traffic Safety Facilities JTG D81-2006 IV. Key points of design 1. The structural system in this general drawing is a simple supported continuous deck structure, which is designed as a fully prestressed member. 2. The plane bar structure calculation software is used for design calculation, and the transverse distribution coefficient is calculated by rigid beam method, and checked by space structure calculation software. 3. Design parameter 1) Concrete: gravity density γ=26.0kN/, elastic modulus EC=3.45 × MPa. 2) Asphalt concrete: gravity density γ=24.0kN/. 3) Prestressed reinforcement: elastic modulus Ep=1.95 × 105 MPa, relaxation rate ρ=0.035, relaxation coefficient ζ=0.3. 4) Anchorage: anchorage deformation and rebar retraction are calculated as 6mm (one end); Metal bellows friction coefficient μ=0.25, deviation coefficient k=0.0015. 5) Uneven settlement of bearing: Δ=5mm 6) Vertical gradient temperature effect: value shall be taken according to the Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts (JTG D62-2004). 　　

1、 Technical Standards and Design Specifications 1. Technical Standards for Highway Engineering JTG B01-2003 2. General Specifications for Design of Highway Bridges and Culverts JTG D60-2004 3. Design Specifications for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts JTG D62-2004 4. Technical Specifications for Construction of Highway Bridges and Culverts JTJ041-2000 5. Technical Specifications for Design of Highway Traffic Safety Facilities JTG D81-2006 IV. Key points of design 1. The structural system in this general drawing is a simple supported continuous deck structure, which is designed as a fully prestressed member. 2. The plane bar structure calculation software is used for design calculation, and the transverse distribution coefficient is calculated by rigid beam method, and checked by space structure calculation software. 3. Design parameter 1) Concrete: gravity density γ=26.0kN/, elastic modulus EC=3.45 × MPa. 2) Asphalt concrete: gravity density γ=24.0kN/. 3) Prestressed reinforcement: elastic modulus Ep=1.95 × 105 MPa, relaxation rate ρ=0.035, relaxation coefficient ζ=0.3. 4) Anchorage: anchorage deformation and rebar retraction are calculated as 6mm (one end); Metal bellows friction coefficient μ=0.25, deviation coefficient k=0.0015. 5) Uneven settlement of bearing: Δ=5mm 6) Vertical gradient temperature effect: value shall be taken according to the Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts (JTG D62-2004). 　　

1、 Technical Standards and Design Specifications 1. Technical Standards for Highway Engineering JTG B01-2003 2. General Specifications for Design of Highway Bridges and Culverts JTG D60-2004 3. Design Specifications for Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts JTG D62-2004 4. Technical Specifications for Construction of Highway Bridges and Culverts JTJ041-2000 5. Technical Specifications for Design of Highway Traffic Safety Facilities JTG D81-2006 IV. Key points of design 1. The structural system in this general drawing is a simple supported continuous deck structure, which is designed as a fully prestressed member. 2. The plane bar structure calculation software is used for design calculation, and the transverse distribution coefficient is calculated by rigid beam method, and checked by space structure calculation software. 3. Design parameter 1) Concrete: gravity density γ=26.0kN/, elastic modulus EC=3.45 × MPa. 2) Asphalt concrete: gravity density γ=24.0kN/. 3) Prestressed reinforcement: elastic modulus Ep=1.95 × 105 MPa, relaxation rate ρ=0.035, relaxation coefficient ζ=0.3. 4) Anchorage: anchorage deformation and rebar retraction are calculated as 6mm (one end); Metal bellows friction coefficient μ=0.25, deviation coefficient k=0.0015. 5) Uneven settlement of bearing: Δ=5mm 6) Vertical gradient temperature effect: value shall be taken according to the Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts (JTG D62-2004).