Chain Survey

Chain survey/surveying is an very old method of Surveying. This article includes definition of chain survey along with all detailed information with necessary images about various aspects of chain surveying. 

Chain survey is the simplest method of surveying. In chain survey only measurements are taken in the field, and the rest work, such as plotting calculation etc. are done in the office. Here only linear measurements are made i.e. no angular measurements are made.This is most suitable adapted to small plane areas with very few details. If carefully done, it gives quite accurate results.

The necessary requirements for field work are

• Chain
• Tape 
• Ranging Rod 
• Arrows 
• Cross staff

Suitability of Chain Survey

Chain survey is suitable in the following cases:

1. Area to be surveyed is comparatively small
2. Ground is fairly level

Prestressed Concrete

          Prestressed concrete, the improved condition of RCC (Reinforced cement concrete) where steel is used as both compression and tension member.

       Prestressed concrete is used in structure where higher load is to be sustained such as bridge, arch structure etc. Addition bars are used in tension face of Reinforced Cement Concrete (RCC) member which kept upon tension at the beginning of casting. After casting of the member the tension is to be cut of which tends to compress again. Thus extra compression is imposed on the tension face of the member which eventually increases the tension capacity of the member. Thus, the basic difference between RCC member and prestressed member is that, addition compression is added in the tension face which rises the capacity then simple RCC member. Thus the concrete is prestressed.


keyword:  prestressed concrete beams prestressed prestressing pre stressed prestress pre stress prestressing

Reinforced Concrete

 

 

What is Reinforced Concrete

Concrete is the combination of aggregate and cement where cement is used as the binding material between the aggregates. This combination has got high compressive strength along with very low tensile strength. But structure members also need to sustain in tensile stresses. For an example, a beam in a building undergo both tension and compression. Compression arises on the upper face of the beam whereas tension develops in the bottom face.
If only cement concrete is used that will be good enough to withstand the compression but as it cannot take tension, failure will be initiated in the bottom face. Eventually, the total failure of the member will occur. To reduce this problem, steel bar is inserted on the tension zone of the member as steel has got very high tensile strength. Now the member can now resist compression and tension in combination of steel and concrete as the compression will be taken by concrete on the upper face and tension will be taken by steel on the lower face. Whole system will behave as one in resisting loads of the structure and the concept of reinforced concrete arises. So the reinforced concrete or reinforcement concrete is defined as the combination of steel and concrete which can take both tension and compression arises in a member as one.


For a strong, ductile and durable construction the reinforcement needs to have the following properties at least:

• High relative strength 
• High toleration of tensile strain 
• Good bond to the concrete, irrespective of pH, moisture, and similar factors 
• Thermal compatibility, not causing unacceptable stresses in response to changing temperatures. 
• Durability in the concrete environment, irrespective of corrosion or sustained stress for example. 

Limitations of Pushover Analysis

Although pushover analysis has advantages over elastic analysis procedures, underlying assumptions, the accuracy of pushover predictions and limitations of current pushover procedures must be identified. The estimate of target displacement, selection of lateral load patterns and identification of failure mechanisms due to higher modes of vibration are important issues that affect the accuracy of pushover results. Target displacement is the global displacement expected in a design earthquake. The roof displacement at mass center of the structure is used as target displacement.




 Related Posts:

• Pushover Analysis/ Seismic Analysis of Structures
• Use of Pushover Analysis Results

Keywords: Pushover push over analysis limitation disadvantage disadvantages Earthquake performance structure civil engineer engineering rcc steel 

Use of Pushover Analysis Results

Pushover analysis has been the preferred method for seismic performance evaluation of structures by the major rehabilitation guidelines and codes because it is 5 conceptually and computationally simple. Pushover analysis allows tracing the sequence of yielding and failure on member and structural level as well as the progress of overall capacity curve of the structure. The expectation from pushover analysis is to estimate critical response parameters imposed on structural system and its components as close as possible to those predicted by nonlinear dynamic