Thuan Phuoc bridge is a suspension bridge cross Han river which run into Đà Nẵng bay. It connects Nguyen Tat Thanh str with Man Quang bridge between Hai Chau District and Son Tra District, Da Nang city.
I. General introduction about Thuan Phuoc bridge project
1.1 Construction position
Thuan Phuoc bridge is located on the route which was invested to build from Da Phuoc interchange, Thuan Phuoc Ward, Hai Chau District to Yet Kieu interchange, Tho Quang Ward, Son Tra District. It helps to connect center of Da Nang to Son Tra peninsula (figure 1). Total length of this route is chosen as 4.208m, in which the length of Thuan Phuoc bridge is 1.855m.
1.2 Design load
– Runway lane : Live load H10, consultant X60
– Sidewalk lane : 300kg/m2
– Wind load : 59m/s (Wind grade 12)
– Earthquake grade : Grade 7
1.3 Construction range Thuan Phuoc suspension bridge was designed with permanent construction, bridge width ensure for 4 lanes of runway and 2 lanes of sidewalk. Design load correspond with H10,X60 following the 22TCN-18-79 specification, pedestrian load 300 kg/m2. The bridge was also designed to handle wind grade 12 and earthquake grade 7. It was located at the appropriate elevation to ensure 3000Tons ship can go through with the height of the clearance is about 27m. The main design specifications was 22TCN-272-01 Viet Nam specification, combined with some specifications of USA and China.
II. The result of evaluate and analysis the bearing capacity of approach bridge
Approach bridge structure: (Part 1 (Straight part 3x50m); Part 2 (Curve part 5x50m); Part 3 (Straight part 4x50m) ensure the requirement bearing capacity of design live load H10-X60 (Correspond with 0.65 HL93); ensure the safety with 3 types of vehicle in 41:2012/BGTVT. Factor RF of span structure following the smallest service limit state of part 1 with tensile stress RF = 3162/1602 = 1.97; Part 2: RF = 3162/1325 = 2.38; Part 3: RF = 3162/1602 = 1.97.s
Approach pier structure: Pier T3, T4, T5, T23 have evaluate factor RF<1 (following evaluation specification AASHTO-2011), cannot ensure the safety in using with rotate moment for design load and 3 trucks load design. It needs to strengthen the bearing capacity for body of the pier and the pier cap. This due to bearing arrangement plan in curved bridge is not appropriate which leads to additional horizontal force into the bearing due to temperature expansion, great live load and rotate moment inside the pier.
III. Failure situation and repairing solution.
a. Failure situation
§ The cracks appear a lots from the top of pier cap to pier body on every sides of the pier.
§ Some cracks appear from the bearing to center of the pier. Its length is equal as the length of the pier cap.
§ Some straight cracks at center, body of the pier with the width 1mm, the length from the top to pile cap.
§ Cracks due to shrinkage and bearing appear the bottom of the pier.
§ Some cracks can be developed by time, length, depth and width.
§ The widest crack at the pier bottom is 1.52mm which are distributed in the length from 0.5-2.5m and the depth is 17-22cm
§ The width of crack at pier cap is 0.05-1.1 mm on the length of 2m
§ Carbonat phenomenon happen significantly.
b. Repairing solution
§ Repairing the failure due to concrete crack and broken.
The crack and broken position must be cleared, cleaned and patchwork by no shrinkage concrete with minimum strength f’c = 28Mpa. The technical requirement in repairing the concrete need to be followed the ACI 546R and ACI 546.3R-06 specifications. Before repairing, the reinforcement must be cleared the rusty if it have. The abutting part between the new and old concrete need to use connection grout (adhesive) to ensure the good adhesion between two parts. § Concrete crack and broken due to reinforcement corrosion.The concrete crack and broken position due to reinforcement corrosion must be cleared, cleaned, painted and patchwork by no shrinkage concrete with minimum strength f’c = 28Mpa. The technical requirement in repairing the concrete need to be followed the ACI 546R and ACI 546.3R-06 specifications.
§ Concrete crack due to construction or lack the bearing capacity. All cracks on the surface of concrete which have the width larger than 0.01in (0.25mm) must be treated by pumping Epoxy adhesive following the ACI 224.1R specification. The smaller cracks need to be pumped the polymer or cover by Carbon fiber, glass fiber to prevent reinforcement corrosion. FRP material must be constructed after pumping the Epoxy adhesive for 24 hours.
IV. Some images in constructing FRP.