Padma Bridge

At the Padma Extension site in Bangladesh, AECOM utilized best in class innovation and imaginative debacle counteraction and moderation answers for tackle some extreme difficulties. At 6.15 kilometers (3.8 miles) long, the Padma Scaffold is a milestone structure and one of the longest stream intersections on the planet. The Padma Waterway is the third biggest stream on the planet, and has the biggest volume of silt transport. During storm seasons, the Padma Waterway turns out to be quick streaming and is defenseless to profound scour, requiring profound heap establishments for connect dependability. The Padma Scaffold site is likewise in a region of extensive seismic action, bringing about critical tremor powers being applied on the extension. This mix, along with different powers of nature, represented a one of a kind test. The multipurpose Padma Extension itemized configuration venture has been effectively finished. AECOM created elective solid deck structures, including an extra dosed solid support connect, a solid brace connect and a steel bracket connect. In all cases, a two-level structure was picked, having critical points of interest over a solitary level structure. These included isolated roadway and railroad envelopes to offer upgraded wellbeing, improved activity, assessment, upkeep, and crisis clearing methodology, just as proficient arrangements for utilities. With the railroad in the lower deck, the basic profundity underneath the railroad is decreased, permitting the lengths of the rail route approach viaducts for tie-in at the north and south banks to be limited. With a two-level structure the development cost is decreased, making the structure progressively productive. Explanatory models were created for every one of the extension structures to decide part estimates and, specifically, the heaviness of the superstructure. The steel support connect was seen as the most proficient with the lightest deck. Further subtleties of this alternative were created to decide the ideal range length. All out deck weight and establishment loads were analyzed for range lengths of 120 meters, 150 meters and 180 meters (394 feet, 492 feet and 591 feet, individually). From this information, a development cost was assessed for each range length with the ideal range being 150 meters. Taking everything into account, the most monetary and suitable structure for the scaffold was seen as the steel bracket connect with a solid top section acting compositely. The multipurpose scaffold additionally has numerous utilities incorporated with it, including a gas pipeline, broadcast communications and a high-voltage power transmission line. Also, it has crisis passages so as to encourage clearing of a train on the lower deck. A point by point investigation of seismic risk at the site was performed to decide appropriate seismic boundaries for use in the structure. Two degrees of seismic peril were received: Working Level Tremor and Possibility Level Quake. Working Level Seismic tremor has an arrival time of 100 years with a 65 percent likelihood of being surpassed during that period. Possibility Level Seismic tremor has an arrival time of 475 years with a 20 percent likelihood of being surpassed during a 100-year connect life period. Any harm continued from such a seismic tremor would be effectively discernible and fit for fix without destruction or segment substitution. Related to these examinations, AECOM completed further investigation to decide the ideal establishment structure, and two heap types were explored; enormous width (3 meter; 10 feet) raking steel cylindrical heaps and huge measurement cast-in-situ concrete exhausted heaps. Raking heaps were progressively effective in opposing parallel burdens coming about because of quake movements. This kind of burden is opposed as hub power in the steel heaps, while the horizontal burden is opposed by the flexural limit of the heaps for the solid exhausted heaps. The extremely huge bowing minutes produced by a seismic occasion directed that inadequate flexural limit could be made by support alone, and a lasting steel packaging would be required to improve the limit down to 10 meters (33 feet) beneath the riverbed level, which for a 100-year scour occasion would be - 61m PWD. It would likewise be important to have in excess of fifteen 3-meter (10 feet) distance across vertical solid heaps, contrasted with eight raking steel cylindrical heaps. The huge number of heaps expanded the heaviness of the heap top and furthermore the nearby scour. These elements adverse affected the expense and construct ability of the establishments, in this way the favored arrangement was suggested similar to the raking steel cylindrical heaps. The conduct of the scaffold is unpredictable because of its stature, which is 120 meters (394 feet) when the impacts of scour are thought about, and the huge mass of the superstructure, heap tops and heaps. A three-dimensional non-direct time history dynamic investigation, utilizing a changed Penzien model, was embraced. It was partitioned into two sections, the structure and the free field soil. The cooperation's between the structure and the free field were mimicked by horizontal spring joins. So as to decide the proportional shear modulus and successful damping proportion between each layer of the dirt, free field investigation was done heretofore utilizing the Shake examination program. Accordingly, a three-dimensional unique investigation was completed utilizing the proportional shear modulus and compelling damping as info information. Ground movements were applied to the model to recreate the quake case, and loads were created in the heaps and base in like manner. Albeit other burden mixes were thought of, for example, transport effect and wind, these impacts were not seen as basic for the foundation, and the seismic burden blend directed the design. A further model was created to research the worldwide conduct of the scaffold. The scaffold is separated into six range modules, each length 150 meters (492 feet) in length, so the worldwide investigation model inspected an individual six range module and applied various degrees of scour at every dock. A scour opening may conform to an individual wharf, or around at least two docks. The worldwide model took a gander at different mixes so as to decide the basic hub, shear and bowing burdens on the establishments of a specific dock. Introductory investigations of the extension depended on the deck being upheld by conventional sliding course, with the purpose of fixity being the focal wharf of the six-length module. To maintain a strategic distance from the fixed wharf being vigorously stacked during a seismic occasion by a longitudinal interpretation, stun transmission units were proposed at the free docks to guarantee even load conveyance between the docks. In any case, under this framework, the heaps applied to the wharf s were still huge; along these lines, as a feature of the worth building process, AECOM thought about elective types of verbalization. The first seismic structure technique was to disseminate seismic vitality through plastic pivots at the base of the wharf s. Further plan streamlining recognized the advantages of seismic separation, which permits the structure to act flexibly without harm. The utilization of seismic seclusion has diminished the quantity of heaps, the size of the heap tops and the size of the steel superstructure, bringing about a more financially savvy plan. Seismic segregation course have been utilized worldwide to alleviate seismic reaction by detaching structures from seismic information. They can suit warm developments with least opposition, yet will draw in under seismic excitation. In this methodology, all essential basic individuals stay versatile with no harm or plastic pivoting. Segregation course contain three key components: one to give inflexibility under help burdens and sidelong adaptability past assistance loads, one to give self-focusing capacity, and one to give vitality dissemination. These key components must be appropriately structured and calibrated to accomplish ideal seismic behavior. Analyses demonstrate that seismic powers can be incredibly diminished by supplanting ordinary pot orientation with disconnection direction. Erosion pendulum orientation use the attributes of a pendulum to stretch the normal time of the detached structure to decrease the contribution of tremor powers. The damping impact because of the sliding instrument likewise mitigates tremor reaction. Since seismic tremor actuated removals happen basically in the course, parallel loads and shaking developments transmitted to the structure are enormously decreased. The decreased seismic stacking produced at the highest point of the extension wharf s essentially diminishes heap loads. With the customary plan of course and stun transmission units, eight raking steel heaps were required for every wharf; with seismic detachment this was diminished to six, prompting a reserve funds in establishment expenses of in excess of 20 percent. AECOM then further built up the structure with the consideration of seismic segregation. The effect of the seismic detachment plot isn't constrained to the foundation; the diminished seismic stacking prompts decrease in area sizes for support individuals, with a general sparing in bracket steel work of more prominent than 6 percent.