Seismic Behavior Of Isolated Bridges
Introduction
Bridges are lifeline structures. They act, as an important page link in surface transportation network and failure of bridges during a seismic event will seriously hamper the relief and rehabilitation work. There are many cases of damage of bridges in the past earthquakes all over the world. Due to their structural simplicity, bridges are particularly vulnerable to damage and even collapse when subjected to earthquakes. The fundamental period of vibration of a majority of bridges is in the range of 0.2 to 1.2 second. In this range, the structural response is high because it is close to the predominant periods of earthquake-induced ground motions. The seismic forces on the bridges can be reduced if the fundamental period of the bridge is lengthened or the energy dissipating capability is increased.
Therefore, the seismic isolation is a promising alternative for earthquake-resistant design of bridges. Considerable efforts have been made in the past two decades to develop improved seismic isolation design procedure for new bridges and comprehensive retrofit guidelines for existing bridges. One of the goals of the seismic isolation is to shift the fundamental frequency of a structure away from the dominant frequencies of earthquake ground motion and fundamental frequency of the fixed base superstructure.
The other purpose of an isolation system is to provide an additional means of energy dissipation, thereby reducing the transmitted acceleration into the superstructure. The suitability of a particular arrangement and type of isolation system will depend on many factors including the span, number of continuous spans, and seismicity of the region, frequencies of vibration of the relatively severe components of the earthquake, maintenance and replacement facilities. .. .
New Techniques Of Waste Water Management
New Techniques Of Waste Water Management
Introduction
Water is a vitalizing force for sustaining life on earth. About 1/3rd of worldâ„¢s population depend on groundwater sources for survival. The individual requirements of water are 135 liters per day, equivalent to 49,275 liters per annum. With steady increasing population and increase in demand for water, the management for water has become a topic of serious concern. There are various techniques of wastewater management which improve the quality of water and which can be used for many purposes. . Decentralized water management is one such solution. With limited water sources in ground and limited space for disposal of waste water, the colleges and connected hostels find the problem of wastewater dumping and unavailability of safe drinking water. Setting up of treatment plants in and around the areas of institutions can control the problem of water scarcity. Many companies have made research and have succeeded in discovering more innovative methods and technologies for wastewater treatment.
Impact Of Lightining On Building And Its Remedial Measures
Impact Of Lightining On Building And Its Remedial Measures
Introduction
Lightning is one of the more spectacular and awesome weather phenomena. Lightning comes in various types and forms. Usually the intricacy of lightning is not visible to the human eye, because it happens so quick; but time-exposure photos catch and reveal the beauty of lightning very well. Lightning is dangerous, but without lightning, there might not be life on this planet. The National Board of Fire USA reports that lightning is the number one cause of farm fires. Lightning is also responsible for more than 80% of all livestock losses due to accidents and millions of dollars in damage to farm buildings and equipment annually.
A system that protects the family, livestock and farm property from lightning strikes prevents or significantly reduces these dangers. Lightning protection systems should be installed only by qualified individuals who have the necessary credentials and equipment. However, a working knowledge of the principles of lightning protection will help to communicate with these experts and oversee the proper maintenance of the system once installed. .. .
Fire Behavior Of Steel Penetrating Concrete Wall
Fire Behavior Of Steel Penetrating Concrete Wall
Introduction
It is often desirable for structural steel members to pass through a fire wall or common wall rather than being curtailed on each side of the wall. In such cases, the penetrating member will often be fire protected for a certain length on each side of the wall so as to minimise the possibility of fire spread through heat conduction and excessive temperature rise of the member on the unexposed side of the wall. This latter aspect is necessary to ensure that lateral restraint will continue to be provided to the top of the wall by the member on the unexposed side of the wall.
Such fire protection can be costly and it is not clear that it is necessary. The reasons for this is that although a steel member is heated intensely on one side of a wall, this heat will be readily conducted to the unexposed side where it will be lost by radiation and convection to the surroundings. Some heat will also be conducted into the concrete wall.
The ability of a penetrating member to act as an effective bracing member depends on the temperature of the member on the unexposed side of the wall: if the member is too hot, it will have insufficient stiffness to provide effective restraint. Similarly, high temperatures could lead to ignition of combustibles should these be in contact with the members on the unexposed side. ..
Bio “ Engineering Techniques For Erosion Control In Slopes
Bio “ Engineering Techniques For Erosion Control In Slopes
Introduction
Soil erosion occurs wherever water meets land with great force to move the soil. This occurs along the stream banks or excess water flows over hill slopes. Erosion can be dramatic, especially after heavy rainfall or floods. Erosion can be severe, as is the case in many man-made lakes, where shorelines are composed of easily erodable soil. Traditional methods of controlling the erosion have relied on structural practices like riprap, retaining walls and sheet piles. In many cases, these methods are expensive, ineffective or socially unacceptable. An alternative approach is bio-engineering, a method of construction using living or non-living materials along with organic or inorganic material to produce living functioning system which act as a drains and prevent the earth movement.
In bioengineering techniques, plants and parts of the plants are used as a main structural component to reinforce the soil, and control the erosion. Bioengineering is a diverse and multidisciplinary field requiring the expertise of engineers, botanist, soil scientists and construction contractors. It is a rapidly growing field, subject to a innovations and changing design specifications. The increased environmental consciousness often makes bioengineering solutions more acceptable than traditional methods.
Bioengineering can prove to be an effective tool for slope protection in road project. Bioengineering stabilizes the ground surface to prevent the surface erosion, however, it does not stabilize inherently unstable slopes that are excessively steep, poorly drained or poorly consolidated.
Seismic Isolation Devices
Seismic Isolation Devices
Introduction
Many structures have their fundamental frequencies of vibration within the range of frequencies where the energy of most of the earthquake ground motions is a maximum. In such cases a structure will amplify the ground vibrations and produce accelerations, which increases from the base of the structure to its top. Besides producing undesirable levels of acceleration in the structure, these amplified structural motions can cause large stresses in structural elements and large relative displacements between different parts of the structure. This can result in permanent damage to parts of the structure or even to catastrophic collapse. The amplified accelerations throughout the structure act on the occupants and contents of the structure and can cause harm and damage to occupants and contents even when no structural damage occurs.
The use of seismic isolations bearings permits the structure to be less strong than would be required if the structure were to have it base fixed to the ground. This results in a lower cost and lower weight of structure. It is an exceptionally effective method for the practical and economical retrofitting of structures that to do not meet current seismic standards, or for which a higher degree of safety is desired. Especially, for retrofit of those structure that cannot afford to stop functioning, this method found to be very useful. This would be especially important for such structures as hospitals, emergency centers, communication centers, disaster response center, power stations etc. Proper isolation of structures such as nuclear power plants, oil refineries, chemical plants and processing plants can also prevent potentially catastrophic secondary harm from occurring due to damage of such systems as a consequence of an earthquake. For many industries and businesses, the most significant benefit deriving from seismic isolation can be the prevention of loss of operation during and after a major earthquake.
However, for effective functioning of seismic isolation, it is necessary to have isolation devices that can fulfill the essential requirements as well as be durable, less expensive and require minimum maintenance during the lifetime of structure..
Rehabilitation And Repairs Of Corrosion Distressed Structures By Composite Fibre Wrapping And Electrochemical Techniques
Rehabilitation And Repairs Of Corrosion Distressed Structures By Composite Fibre Wrapping And Electrochemical Techniques
Introduction
Deterioration of reinforced concrete structures due to corrosion of steel is a cause of global concern. The losses due to corrosion every year run into millions of rupees and any solution to this universal problem of corrosion has a direct bearing economy of the country. It is estimated that about 30-40 percent of steel produced each year is used to replace corroded material.
In recent years, the construction industry has seen an increased demand to reinstate, rejuvenate, strengthen and upgrade existing concrete structures. This may be attributed to various caused such as environmental degradation, design inadequacies, poor construction practices, lack of regular maintenance, increase in loads due to change in usage or unexpected seismic loading conditions in addition to corrosion induced distress. Advanced composite techniques and electrochemical techniques are the two types of techniques used in strengthening and protecting corrosion distressed structures. .. .
Feng Shui And Vaastu Shastra
Feng Shui And Vaastu Shastra
Introduction
The name Feng shui is derived from two words, which are Feng and shui. Feng means "wind," and shui means "water" (pronounced fung-shway). In Chinese culture, gentle wind and smooth water have always been associated with a good harvest and good health, while harsh winds and stagnant water have been linked to famine and disease. Therefore, "good" feng-shui has come to mean good livelihood and fortune, and "bad" Feng-shui has come to mean hardship and misfortune.
Feng shui is the chinese art of placement which helps us to create harmony, balance the positive energy in our environment through the proper use of furnishing, art, mirror, objects, plants and all others around and in our environment. Positive energy is created in our environment by work with the natural flow of energy.
Monolithic Concrete Domes
Monolithic Concrete Domes
Introduction
Today, in this modern world, there are different types of structure they may be either a steel structure or concrete structure or the combination of both steel and concrete or structure made up of other material. Of these structures the Monolithic concrete dome is the latest and of great demand of structure constructed. In 1976 Mr. David B South and his brother Barry and Kandy South developed an effective method to develop Monolithic domes and in 1979 first monolithic dome was constructed in Shelley Idaho. Right now there are number of monolithic building in the world. There is a institute (chairman. David B.South) in the Italy, which are, doing research work on various aspect of the domes they also provide design of the monolithic domes.
The monolithic word is made up of two words Monolithic= mono+lithic Mono means single Lithic is derived from a Greek word Lithos which means A large single upright block of stones. Domes are of roof shaped like the top half of ball. The Monolithic concrete dome is a super insulated, steel reinforced concrete structure. Monolithic domes have many advantage such as strength, permanence of the structure, energy efficiency, cost effectiveness, attractiveness and disaster resistance. Monolithic domes have been constructed for public buildings, schools, gymnasiums, churches, office, and bulk storage. ..
Runway Resurfacing And Repair Using Modern Materials & Techniques
Runway Resurfacing And Repair Using Modern Materials & Techniques
Introduction
Repair and resurfacing of runway is a complex activity, which requires comprehensive engineering evaluation, selection of suitable materials commensurate to problems and proper co-ordination of construction procedure, and activities. It also demands setting up adequate quality planes and quality assurance methods .For runway resurfacing it is required to determine the nature and extent of deterioration and also the causes of deterioration. For this it is essential to carryout detailed study including overall projection evaluation so as to evolve suitable repair alternatives. In the present paper an attempt has been made to bring out certain salient features of planning and execution of Runway Resurfacing work based on a case study... .
Mineral Admixtures For High Performance Concrete
Mineral Admixtures For High Performance Concrete
Introduction
High Performance Concrete (HPC) is the latest development in concrete. It is not just High- Strength Concrete (HSC) and has replaced HSC developed in the early 1980â„¢s. HPC can be defined as a concrete made with appropriate materials (super plasticizer, retarder, fly ash, blast furnace slag and silica fume) combined according to a selected mix design and properly mixed, transported, placed, consolidated, and cured to give excellent performance in some properties of concrete, such as high compressive strength, high density, low permeability, and good resistance to certain forms of attack. What makes the concrete a high performance one is a very low water-cement ratio. The benefits related to HPC include: early stripping of formwork, greater stiffness and higher axial strength. These factors combined lead to the elements of high economic efficiency, high utility and long term engineering economy.
Space Hotel
Space Hotel
Introduction
As tourism activities around the world grow to include more and more varied offerings, the idea of space tourism - members of the public making trips to and from low Earth orbit and beyond - has started to be recognized as a serious possibility. The subject of space tourism has also recently gained credibility among professional space organisations as a possible means for the commercialisation of space activities. This study concluded that space tourism was indeed a realistic possibility; it is likely to start soon; and it will grow larger than all commercial activities in space today
Construction Challenges For Bridges In Hilly Area
Construction Challenges For Bridges In Hilly Area
Introduction
Hilly region pose unique problem for bridge construction. In a restricted hilly area itself climatic conditions, geological features and hydrological parameters vary considerably. Keeping in view the bridge site and various constraints, type of bridge and method of construction are to be selected carefully for safe, economical and successful completion of bridge construction.
Various challenges that come across while constructing bridges in hilly area are
1. Construction of bridge across deep gorges
2. Construction of bridge on rivers with bouldary beds
3. Construction of bridges in extreme temperature zones
4. Construction of bridges on sharp turn on highway
5. Landslide or Debris flow
Deep gorges, rivers with bouldary beds, extremely low temperature condition, high winds, landslide etc. in hilly regions require special attention to complete the activities of bridge planning and construction in a systematic way and are discussed here in.
Design Considerations For Roadside Safety
Design Considerations For Roadside Safety
Introduction
There has been tremendous growth is roadway travel in India in the last two decades. The developments of roadways have not kept pace with the increase in demand of travel. This has resulted in traffic congestion, delay, discomfort and increase in accidents. Proper planning, design construction and maintenance of roadways can reduce this accident.
Even if every reasonable efforts taken by highway engineers to design the highway facilities so that the vehicles stay on the road, motorists may continue to runoff the road. This could be because of various reasons “ driver error, excessive speed fatigue of drivers leading to inattentiveness, reckless driving or driving under the influence of alcohol or drugs, which are beyond the control of the highway engineers. Often drivers leave the roadway to avoid collision with another vehicle or with fixed objects. Poor roadway geometry, Poor visibility in bad weather, poor pavement condition, inadequate drainage, substantial signing and marking. All these factors causes motorists to get off the road
