2. What are the secondary components (appended members) of bridges? (10) Pavement, drainage system, barrier, expansion joint and lighting.
3. How to divide the type of bridges according to the structural form? (10)
①Girder bridge: It is a bridge whose main bearing member is dominated by bending.
②Arch bridge: It is mainly under pressure and made of brick, stone, concrete and other materials with good compressive properties. It is also applied for horizontal force.
③Rigid frame bridge: It is a bridge whose girder and pier are connected by rigid connection.
④Suspension bridge: Cables are suspended and anchored on both sides of the bridge. A lot of suspenders are hung from the cable and the bridge deck is hung.
⑤Cable-stayed bridge: The cable-stayed bridge is mainly composed of pylon, main girder and stay cable. The main beam is pulled directly on the pylon with many cables.
4. Describe the concepts of permanent action and variable action, and provide examples for them. (15)
Permanent Action: Loads and forces are constant upon completion of construction or varying only over a longtime interval. The force’s three elements, magnitude, direction and point of action are almost no change.
Example: Self weight, prestress, self weight of earth, lateral pressure of earth, shrinkage and creep, buoyancy and settlement of support.
Variable Action: Loads and forces that can vary over a short time interval relative to the lifetime of the structure. Several elements of the force’s three elements are changing in a short time.
Example: Vehicular load, impact load, centrifugal force, lateral pressure due to vehicle, pedestrian live load, braking force, wind load, water load and stream pressure, ice pressure, thermal load and support friction.
5. Describe the load path in cable-stayed bridge and suspension bridge, respectively. (15)
Cable-stayed bridge: The main beam of the bridge carries the loads of vehicles and pedestrians. The cable is subjected to axial tension and pull the main beam of the bridge. It is a symmetrical structure, the two forces, horizontal left and horizontal right, cancel each other out. So it only has vertical force, which is transmitted to the pier.
Suspension bridge: The kinds of vertical loads act forces on the beam of the bridge, which is transmitted to the main cable through the boom. The suspension part transfers the force to the bridge at both ends of the bridge. These two parts are connected by vertical booms.
6. What are the basic requirements of the bridge design based on use, economy, dimension, construction, and aesthetics? (15)
Use: The bridge should have enough carrying capacity to ensure comfort and safe of driving.
Economy: Having satisfied the requirements of use and safe, total cost economy is should be considered.
Dimension: According to different bridges’ main span and local geography to determine which bridge is appropriate to use.
Construction: Every kind of bridge has different characteristic and range of application. Consider many factors such as economy, span, materials and foundation to determine the sort of bridge. Aesthetics: The structure is harmonious and has good proportion. It is also has a graceful shape and in harmony with surroundings.
7. Briefly describe the bridge design process. (15)
The first is preparation stage which includes two main parts, pre-feasibility study and feasibility study. Pre-feasibility study mainly to discuss the necessity of construction and the rationality of economy. Feasibility study mainly to discuss feasibility of engineering and investment. Through the investigations to environmental conditions, draw a 1/10000 topographic map. Cost returns and sources of funding are considered. Next is preliminary design, draw a 1/2000 topographic map and determine the layout design and a main span. Research project and construction arrangements and designs are needed, too. Then is technique design. The work is supplement exploration and to have a further study to solve technique problems. The last is construction drawing design. The drawing should satisfy the construction practice.
8. What are the differences between the vehicle load and the lane load? (10)
Vehicle load: It is to calculate local loads of bridge. Regard a large number of cars and cars’ arrangement as design load.
Lane load: It is to calculate whole actions, such as mid span bending and shear force, dead load and live load are included. It is expressed as a concentrated force with uniform loads.
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