Bridge design at wami river final year.

In general a bridge project can be considered to have three major stages. They are, 1. Investigation stage 2. Design stage & 3. Construction stage Unlike the building structure constructions, bridge projects require an intensive investigation based on the feasibility, requirement or necessity, population benefited, economic development expected, topography, hydraulic data and soil characteristics prior to the approval and design stages. After all such investigations being over, the design stage commences. The design stage, consists of mainly three elements; hydraulic design, geometric design and structural design. Hydraulic design accounts for calculation of flood discharge, scour action near the bridge supporting structures, characteristics of river channel to fix the level of the bridge, clear water way of the bridge and thus the bridge spans. Foundation depth based on hydraulic characteristics is also a point to be considered. In geometric design, vertical and horizontal alignment and curvatures required are to be established. Traffic flow characteristics, projected traffic over one or two decades are to be considered. Thus the geometric design concerns more with transportation engineering point of view. Structural design involves the selection of component types and providing an economical solution for the purpose intended based on strength and serviceability point of view. At the end of design stage estimations, drawings and approvals are vital roles to be performed. At the construction stage, one cannot start the construction of bridge all of a sudden without certain preparatory works. Apart from primary construction surveys, river training works, coffer dam construction, approaches for machinery and equipments, storage and security for materials are important elements of bridge project under construction stage. Material and manpower management are also vital tasks for construction managers at this stage. There are design specific and bridge type specific construction technologies that could be adopted at this stage (like slip form, cantilever form techniques etc.). 2.3 DESIGN OBJECTIVES The general objective of bridge design is to provide economic, viable and safe solution to cross an obstacle such as river, valley and other traffic flow, by means of proper selection of site, material, type, technology and design. Specific objectives can be listed as follows: 1. to provide economic, strong and durable design of bridge 2. to provide the shortest structure across the obstacle 3. to forecast and decide the expected traffic flow in the future decades to come and to finalize the structural dimensions 4. to study the hydraulic data and fix economic spans for the bridge superstructure 5. to include applicable load combinations to design the structural components with the help of appropriate design code DESIGN WORKING LIFE Concrete, stone and steel bridges shall be designed for 100 years working life. Concrete and Steel culverts with an opening or diameter less than 2.0 m and all timber bridges shall be designed for 50 years working life.

The Guidebook 2 is written in a user-friendly way employing only basic mathematical tools, supplemented by examples and case studies developed in detail. A wide range of potential users of the Guidebooks and other training materials includes practising engineers, designers, technicians, experts of public authorities, young people-high school and university students. The target groups come from all territorial regions of the partner countries. However, the dissemination of the project results is foreseen to be spread into all Member States of CEN and other interested countries.

Handbook of International Bridge Engineering, 2013

The project includes a cable-stayed bridge and two approach viaducts: one on the Chaco side on National Route 16 and another one on the Corrientes side on National Route 12 (Figure 3.22). Those structures are 2000 m long (1666 m over water) and 8.3 m wide, with one lane in each direction. The vertical navigation clearance is 35 m. The required horizontal clearance is 200 m. The cable-stayed bridge comprises three spans (163 m + 245 m + 163 m). It is composed of two 225 m long suspended structures, placed symmetrically along the main pylons axes, which are 245 m apart. A simply supported span of 20 m links these two structures to form the main span of 245 m. This suspended span reduces the effect of deflections on the two main structures. Each main pylon is a W-shaped frame that rests on a pile cap for its foundation. A set of eight stays completes each main 83 m high pylon. The cross section is a two-box girder. The deck is completed with precast transverse slabs, 6.9 m long and 2 m wide, supported on the main beams. When the deck was finished, the transverse beams were prestressed. The original stays were of the locked coil type, but they had to be replaced after 25 years of service. The longitudinal beams of 3.5 m deep were prestressed. The approach viaducts over the river are composed of nine spans of 82.6 m each on the Chaco side, and three spans of 82.6 m each on the Corrientes side. They were built by the balanced cantilever method with precast segments 4.1 m long and 2 m deep at center span and 4.5 m deep over the supports. The overall deck width is 11.3 m, carrying two 3.65 m wide lanes, narrow emergency shoulders of 0.50 m and pedestrian sidewalks 1.5 m wide. The piers of the approach viaducts are constant deep box sections and were built by the sliding formwork method. The foundations were made using 1.8 m diameter bored piles with variable lengths between 38 m and 60 m, and with preloading cells, they are clamped by penetration into the hard clay stratum. At around 20 years of service, the replacement of all the stays was required. Construction works were carried out by Freyssinet SA (Spain) in 1995. Parallel strands stays were installed. The link between both cities, with only two lanes, has proven to be insufficient for the traffic, which has been ever-growing since its construction. The construction of a new bridge is now under consideration. Construction work began in August of 1968 by the initiative of the governments of the provinces involved: Corrientes, Chaco, and Formosa. The owner was DNV, who called for international bids in 1965.

The presence of a bridge structure in the river induces changes in the natural geometry of the river cross section by, therefore, altering the hydraulic regime significantly and causing the so-called backwater effect. Nevertheless, the effect of the bridge configuration on the hydraulic regime is barely studied. Therefore, the main objective of this study is to investigate the variations in the water surface profile and flow velocity due to the bridge structure configuration. For this purpose, the water surface profile and flow velocity on the upstream and downstream of the bridge were investigated for five flow discharges and four different bridge spans (M = b/B = 0.58, 0.67, 0.75, 0.83). In addition, the relationships between the bridge's upstream and downstream average velocities were investigated. The analysis was carried out experimentally and numerically using the HEC-RAS model. The overall average velocity difference upstream of the bridge section was-92.59%, while downstream of the bridge was determined as-11.95%. So, the average velocities determined by HEC-RAS were considerably overestimated at the upstream part of the bridge. Linear relationships were identified for the average downstream and upstream measured velocities in the different openings. The correlation coefficients (R 2) were significantly high for considered for all tested b/B ratios. Manning roughness coefficient n = 0.01 was found suitable for smooth open channel; nevertheless, a higher n value should be considered non-smooth open channel. The solution-oriented findings from this study might be helpful for engineers by assisting them to reduce uncertainties in the dimensioning of bridges structures.

Roads and bridges infrastructure are important factor in development of a region, as it provides land connectivity for transportation of people and goods. Since the sign of peace treaty in 2005, Aceh Province is continuously upgrading its roads and bridges capacity in order to increase the safety and quality of land. In 2014, surveys had been conducted in Cental Aceh to assess the condition of existing bridges, and also detail engineering design for the rehabilitation of old bridges or construction of new bridges had been proposed. Several typical problems of existing bridges were found, such as poor design, poor quality of construction, damages due to river flow and geotechnical problems. This paper summarizes some of the problems along with the proposed solution, and also intended as a documentation that can be used as reference for future road/bridges infrastructure improvement not only in Aceh Province, but also in other part of Indonesia.

Company New Bridges Hydrological & Hydraulic Analysis & Design , 2019

This is a complete report of Hydrological analysis and hydraulic design of Kabul Company Parallel bridges. Which is done by Mohammad Aemal Umar Senior hydrology and hydraulic engineer of THRCP/MOT of Afghanistan.

IRJET, 2023

This paper is a study that summarizes, the procedure used to increase the capacity of an existing concrete bridge in the UAE. Traffic congestion is a severe problem in modern life. Severe congestion can negatively impact the country's economy, environment, and the health of road commuters. The increase in trip duration due to traffic congestion will result in consuming more fuel which results in a higher cost of trip and more emissions which affect both the economy and the environment. Moreover, the road commuter will be traveling for a long time which can affect their sleeping hours and mental health. Constructing more roads, and bridges and encouraging people to use public transport are some of the measures taken to reduce traffic congestion. To evaluate the effectiveness of an existing highway, certain parameters such as traffic quantity, type of vehicles in the traffic stream, speed of traffic stream, and the density of traffic stream will be measured and assessed to determine the need for increasing the road capacity. This paper considers the structural part and challenges faced during the process of widening an existing bridge structure. The existing bridge under consideration is composed of two spans with a length of 33.10 m of each span, two abutments with pot bearing connection, a single monolithic pier, asphaltic plug expansion joint at abutments, voided post-tensioned concrete slab with concrete barriers. The decision was taken to widen the existing bridge to relieve the aggravated traffic jam problem. The development of residential areas nearby resulted in increasing the volume of traffic exceeding the existing road capacity. The new development proposal involves the construction of a completely new bridge with 4 lanes and the widening of the existing bridge. The final output is two bridges with 4 lanes in each direction.

The Detail Project Report is an essential building block for any construction project. The DPR is to be prepared carefully and with sufficient details to ensure appraisal, approval, and subsequent implementation in a timely and efficient manner. The detailed project report gives us the clear idea about the existing site conditions and improvements needed to be accomplished. The DPR survey has been done for construction of a high level bridge on road pertaining @ km 6/2 (R&B) road to Kadapa district. The bridge crosses the river in normal crossing. It has total span of 50.80mts.This work has been executed under MNREGS scheme. The bridge has 3 vents of 6.37m effective span. The bridge is constructed across the stream to provide transportation facilities to people of Proddatur to various places of Kadapa District. This stream has an adequate discharge of 97.00 cusecs and it increases more during in rainy season. Traffic studies have been conducted on this road and the outcome was 120cvpd. The maximum flood level of this stream is 99.830.The linear water way is 18.00m. The design drawings and plans were given by MORT&H for execution of work. To calculate the discharge levels has been surveyed around 300mts both upstream and down streams. Funding for this project has been given by the government of A.P. The work has to be completed in a period of one year. The total estimate amount of the project is said to be 69.50 Lakhs.