Simulation Of Wind Load On Cylindrical Wall Of Ground Elevated Reinforced Concrete Silo
Desh Bandhu Mukherjee , Amiya K. Samanta and Prasanta Patra
The ground elevated Reinforced Concrete (RC) silo is a very important structure in the material handling and food grain processing plants. The configuration of the structure is normally vertical, right circular and cylindrical. When such a structure is analyzed under wind load, the distribution of internal forces does not follow the typical pattern expected from the beam bending theory due to non-axisymmetric variation of wind pressure along the circular periphery considering the silo as a thin walled tubular structure. The silo wall deforms considerably in its cross section due to ovalisation instability. In case of long cylindrical steel, silo ring stiffeners are provided at intermediate levels of the cylindrical wall in order to reduce this ovalisation effect due to wind load. However, in case of reinforced concrete silo, ring stiffeners are not normally provided to avoid construction hazards during slip forming. The Author(s) have attempted to find a direction in this context through a review of work pertinent to the field. An attempt has been made to simulate the wind load exactly as prescribed by the Indian code of Practice on the cylindrical wall of a typical silo using a highly sophisticated platform of finite element software. The deformation of the cylindrical wall pertinent to the ovalisation phenomenon was studied. In fact, this study also attests and throws light on the variation of hoop stress along the height of the cylindrical wall for the typical configuration only for the structural engineers so as to make the design safe and economic in the context of hoop reinforcement requirement.
Time-Cost Trade-Off For A Fast-Track Project: A Systematic Statistical Approach To Compare With Traditional Concepts
Kazi Arbaz Mubarak , R. B. Magar and Fauwaz Parkar
Every construction project is unique in nature; it needs certain resources, viz. man, material, machinery, money, methodology, time etc. in addition to conducive environment for its successful execution. However, for successful completion of any construction project vis-a-vis planned objectives within the allotted budget and stipulated time is always a difficult task for the management. In order to overcome such obstacles, the fast-track method which is one of the most accepted methods, is used to reduce the overall project duration. However, due to the lack of adequate research on the effects of the fast-track requisition in terms of time and cost, it has been complicated for project owners to determine its correct application. In this paper, an attempt has been made to develop a time and cost based decision support model based on the fast-track method and Genetic Algorithms (GAs). Thus, the objective of this exercise is to help the project stakeholders in deciding the approach to be adopted for a particular project.
Fast-track construction, Resources, Decision support model, Genetic algorithm
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Research Articles
Numerical Assessment Of Probability Of Detecting Defects In Civil Structures
Chandak Vedant S. and Nayak Chittaranjan B.
The probability theory has found its major application in various civil structures for the detection of defects inside the structures. Probabilistic methods provide essential tools used for better assessment of the impact of uncertainties on structural life and risk of failure. The non-destructive inspector must know the probabilistic nature of structural failure. In general, there are various NDT techniques available and it should be categorized into active and passive. The active techniques are those where test medium is applied to the test specimen and response is expected if flaw is present. This response is then detected by some means and recorded. On the other hand, passive techniques are those that monitor the item to determine the presence of defect through some reaction of the specimen. For this, several research works were reviewed regarding the probability of detection (POD) of cracks and from the reviewed literature different methods of POD are discussed. The factors that affect POD data, such as human errors and environmental factors were taken into account. This paper reviews the methods used for numerical assessment of detecting defects in civil structures
Defects, Probability of Detection, Non-destructive Testing
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Research Articles
Performance Evaluation Of The State Level Environment Clearance Authorities With Special Reference To Infrastructure Projects
Mukund Phatak and Harish Kumar Singla
The Environment Impact Assessment (EIA) notification of 2006 essentially lays down the process of according prior environment clearance to eight categories of projects proposed across the country. This EIA notification was issued by The Ministry of Environment, Forest and Climate Change (MOEF&CC), Government of India on September 14th 2006 with a view to avoid delays in granting Terms of References (TORs) and Environmental Clearances (ECs) to various development projects. The notification has a provision to divide a project in two categories i.e. category 'A', to be granted TOR and EC by MOEF&CC at national level whereas category 'B' to be decided by the State Level Environment Impact Assessment Authority (SEIAA), specially created at state level for this purpose. The paper is an attempt to evaluate the performance efficiency of such state level authorities and to assess whether these authorities fulfill the objective of expediting the clearance process by keeping the time schedule mentioned in the notification. The data regarding the applications received by all the state level authorities during the year 2015 for the projects covered under Infrastructure category were analyzed with a view to find the time taken for the clearance of these projects. The analysis reveals that out of 38 projects applied for TOR under this category, only 14 (13 within the time limit while 1 beyond time limit) were granted the TOR within the specified time period i.e. 37%. Whereas out of 48 projects applied for EC, only 4 (3 within the time limit while 1 beyond time limit) were issued EC i.e. 8.33%. The above results give a clear picture of the efficiency with which these state level authorities are performing.
Environment clearance, Infrastructure projects, Terms of reference, Environment impact assessment
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Research Articles
The Cause And Effect Analysis Of Construction Delays On Project Delivery In Indian Infrastructure Projects : A Case Study
Krishnachandran V N
Construction delay has become endemic in the Indian infrastructure industry. It is generally observed that the project delivery is unrealistically delayed. This delay is caused due to several reasons, but all ultimately point towards poor construction management practices. There are several causes of delays. The parties attributable for such delays are the Client, Contractor or Consultant. Sometimes reasons that are not attributable to any of the parties but to natural catastrophes and acts of God, etc. It is also observed that the time and cost overruns are frequent effects of the delay. This paper tries to identify the various delay events that had occurred during the construction of a Hydro Electric Project in a remote location of the Himalayas. There are several challenges and constraints that hamper the progress of a project. A systematic project management approach was required to complete the project successfully. This project had commenced on 9th April 2009 and was expected to complete on 8th January 2013 within the scheduled duration of 45 months. However, the project suffered numerous delay events and variations and was eventually completed on 31st March 2016. This paper tries to identify the various delay events that resulted in the drastic time overrun, about 86% increase in the project delivery. This paper also discusses the various contractual remedies that are applicable to adjust/ recover the loss suffered by the Contractor and Employer.
Construction Delay, Time Overrun, Cost overrun, Contractual Remedies
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