PAPER 1 :- SUSTAINABILITY IN CIVIL ENGINEERING EDUCATION A BRIEF OVERVIEW:-

In short, sustainability can be described as endurance of systems and processes. In any engineering domain, sustainable solutions arise out of better understanding of the context in which the engineering is being delivered. It is imperative to understand that sustainability deals with much complex, messy and socially-economically-technically interlinked issues of the real world problems. With respect to what is considered as “to include in the part of education curricula”, sustainability should not be confined as an extra credit in the courses. Instead, it has to be embedded into every course, wherein its impact shall be reflected. It is the engineering graduates and young engineers, who must take a subtle approach to provide with the honest and most “satisfied” solution which is acceptable to the widest range of community, and also which addresses the maximum of objectives/constraints, rather than to just give “tailor-made” solutions, which may sometimes prove to be feasible, but uneconomical. The answer to the question of “ Why sustainability?” lies in the fact that, we as engineers are responsible to the queries of the society about the human impact on environment. Within the concept of sustainable development, it is imperative to strike balance between environmental, economic and social outcomes. Some key principles are developed not just to protect the environment, but also help the future engineers to optimize the existing resources to meet the “never-ending” demands of society under tight financial constraints. First principle is to “work within environmental limits”, Second principle is to “develop minimum required socio-economic standards”, Third principle is “decisions and actions taken should leave a room for future generations” to live sustainably, and Fourth/Final principle is to “conceive solutions as a part of wider complex system” which means, every intricate link in any civil engineering project must be taken care, so that there are no adverse effects due to lack of any of the infrastructure. Every civil engineer must be aware of the sustainable development issues and also to recognize the nature of impacts (social, environmental, economical), civil engineering projects have on ecosystem. In fact, sustainability is important at every stage of an engineering project, and one

who is well-equipped with sustainability thinking can make a huge difference in every stage. As an example to civil engineering project, construction practices can be improved to reduce the on-site energy usage and waste generated. Business models/ consultancies can provide “service” in guiding the clients to chose the optimum material resources, and real sustainable alternatives for a given project, which can financially save the companies. The overview of the paper comes with the question of “how to stimulate the civil engineering students to approach design, construction and operational aspects, and also help them to evolve into innovative thinking and develop “problem-perspecctive” look. It is proved that these set of skills shall be developed not by teaching, but by various interactive and brain-storming sessions, with a range of complementary learning activities.

(1)First step is “to have a role play in outcome of the decisions for a given project” , where in the students can pour down ideologies and thereby come to understand what a rational decision making is.

(2) Second step is “by acquaintance of students to real-life case studies and field work”, where the students face the complexity of constraints, thereby letting them know how to optimize solutions without any compromise on the quality and efficiency

(3)Third step is “ to compare and understand experimental and simulation work hand-in-hand”, because Simulations can help us understand the “leverage points” in a real time project. Though the students cannot steer the system/project as they wish, the results obtained from a simulation can significantly influence the nature of working of a system/project.

(4)Fourth step is “to accept change challenges” so that the motive of the students is not to gauge the scale and impact of the challenge, but to emotionally connect with the intricacies involved and the experience of success.

(5)Fifth step is “multi – criteria decision making” wherein the student is exposed to study each and every parameter involving a decision making problem, and weigh the consequences of the output, by changing the parameters, as per the importance of its impact over the problem.

(6)Sixth step “is to develop a consultancy service portal” wherein the students have an opportunity to harness the technical skills and can tap the untouched potential hidden while addressing a real life time problem statement.

As an example, many western universities like TU Delft (Netherlands), Brunel University, Newcastle University, Cambridge University, University of Surrey, Imperial College etc. (to name a few) have already incorporated courses that link engineering and sustainability development.

PAPER 2 :- ANGLES IN ECCENTRIC TENSIONA BRIEF OVERVIEW:-

Angles are the most common structural elements used in case of transmission towers, antenna supporting towers, and as web members of steel trusses. Usually, angles are connected by one leg, and are subjected to tension or compression, concentric or eccentric. In such cases, the ultimate load carrying capacity of the members is determined by many factors, such as net area of the connection, yield stress and ultimate strength of material. Effective net area is considered to be less than actual area, when members are connected by one leg, in tension. Different codes consider different percentage of outstanding leg areas, to be effective in carrying tension. AASHTO considers half the area of unconnected leg to be effective, while BS 5950, IS 800-1984, and AS 1250 consider a proportion of area to be effective, based on the areas of connected and unconnected legs. Most important criteria while judging for the design strength of connection is to check for gross section yielding, net section rupture and block shear failure phenomena. The tensile strength of the specimens are governed by the failure criteria as mentioned above, except that AASHTO considers only ultimate strength, and other codes consider yielding strength in addition. Several tests were considered and experimental data is compared to the results obtained from calculations. Nelson (1953) was the first to conduct tests on equal and unequal angles in tension with bolted connections, Gibson and Wake (1942) conducted tests on specimens with welded end connections. Kennedy and Sinclair (1969) conducted tests on single angle single-bolted connections, where in special importance was given to understand the effect of edge and end distances, material thickness, yield and ultimate strengths of material.

Coming to the results, it was observed experimentally that specimens when longer leg is connected had higher failure strengths than, when the longer leg is in outstanding position, which boils down to the fact that, in case of unequal angles, the connected leg size must be taken into consideration. It is also proved that use of close tolerance bolts (fitted bolts) also induce moments in end connections, which may increase failure load. The calculated failure loads were highest for AASHTO than other design codes, because the only failure mode considered was that of ultimate strength, whereas the other codes like IS 800-1984, BS 5950, CAN3-S16.1 all have adopted limit state method of design. Of all the specifications, the notable point is that only AISC Manual no. 52 is the only one which has considered the failure strength due to block shear failure, where the tolerance between the bolt and hole was of the order of 1/16th of an inch. When angles in eccentric tension are connected using fitted bolts, the results were unduly conservative.

PAPER 3 :- SHEAR LAG IN BOLTED ANGLE TENSION MEMBERS A BRIEF OVERVIEW:-

Angles are the most common structural elements used in case of transmission towers, antenna supporting towers, and as web members of steel trusses. Usually, angles are connected by one leg, and are subjected to tension or compression, concentric or eccentric. Most of the cases, it is difficult to connect both the angle legs. This means, the “shear lag effect“ is reflected in determining the effectiveness of the member. The influence of connection of only one of the angle legs on the tensile capacity is referred to as “Shear Lag”. Ratio of stress at ultimate load to the ultimate tensile strength is given as Net Section Efficiency. Munse and Chesson (1963) have quoted that this net section efficiency is a function of several parameters such as Ductility Factor (k1), a factor for method of hole forming (k2), Geometry factor (k3), and Shear lag factor (k4). Shear lag factor is represented as a function of distance of face of gusset plate to the centre of gravity of cross section. To calculate k4, one must know beforehand, the length of the connection. Hence an iterative solution is presented in such cases. LFRD Specifications for steel structural buildings (1993) suggests that for three or more bolts, a factor of 0.85 is used, otherwise a factor of 0.75 is used, for the shear leg factor.

The main objective of the study was to test single angle and double angle specimens for ultimate strengths and then compare the strengths to study the shear lag effect. It was observed that all the specimens failed by tearing, the failure starting from the bolt hole in the connected leg, and propagating along the outstanding leg. ( The failure phenomenon precluded the effect of shear block failure). Also, the inference was the specimen with shortest connection length has the lowest ultimate strength capacity, and the ductility was poor. The ductility for the specimen (at ultimate load level) connected by long leg to gusset plate is observed to be twice that of the connection by short leg. In fact, the double angle specimens also showed similar behavior in ductility performance. Also it is observed that the out of plane deflection was high for single angle members, and for double angle members. At the critical cross section, the strain was largest in the connected leg (at the toe) and smallest at the edge of outstanding leg. A numerical model analysis was also done to observe the effect of shear lag in single and double angles in tension. Following are the inferences from the analysis results :-

(1)It is observed that the thickness of specimen(angle) has very little effect on the net section efficiency.

(2)The connection by longer leg to the gusset plate, resulted in higher net section efficiency than that of the cases where shorter leg is connected.

(3)Connection length had significant impact on section efficiency. For a single angle member, connection of 4-bolts yielded 21% higher efficiency than that of 2-bolt connection angle.

Intuitively, it is expected that the double angles are more efficient than the single angle members. Because (1) out-of-plane stiffness of double angles is nearly infinity, unlike single angles (2) there is no eccentric moment generated, unlike in case of single angle members. The inference is when the angle members are connected by only one of the legs, a percentage of critical cross section area can be used as effective net section area. Viz., 80% if the connection has 4 or more fasteners per line, and 60 % if there are 2 or 3 fasteners per line.

Or, an alternative to the above is when 4 or more fasteners per line are connected in addition to the connection area at critical section, 50 % of the gross area of outstanding leg is used. Else if 2 or 3 fasteners per line are connected, 100 % of the gross area of outstanding leg is used.

PAPER 4 :- REUSE AND RECYCLING RATES OF UK STEEL DEMOLITION ARISINGS A BRIEF OVERVIEW:-

Recycling and reuse of construction materials, has been a topic of global importance, keeping in view the exponential depletion of existing resources, and also the never-ending demands of global community. Also, there have been studies where the retrofitting and renovation of older buildings is to be done, within the financial constraints, and not compromising quality issues. Concrete has been rampant during the era of rapid infrastructure development, but however, the reusability and recyclability of concrete is observed to be very poor. Steel constructions are gaining much importance in terms of speedy construction, reusability and recyclability of the material

after the service life of a structure. Also, from an environmental perspective, recyclability and reuse of material resources will help in evading the peril of environmental degradation, thereby saving the ecosystem, for future generations. In UK, under EU waste framework directive, has set a target of reuse, recover or recycling 70% of the non hazardous construction and demolition work by 2020. When buildings are demolished or deconstructed, following are the outcomes of arisings :-

(1)Reuse(2)Recycling of material (doesn’t include energy recovery) (3)Downcycling (4)Incineration – with or without energy recovery

Downcycling is another form of recycling, but essential difference between (true) recycling and downcycling is that in the latter, resultant material is of lower quality than the parent material. Recovered material in downcycling is not equivalently functional like parent material. Hence, true recycling yields higher environmental benefit than that of the downcycling, thereby maximizing resource efficiency. Steel Construction Institute (SCI) has conducted a survey, regarding the expert opinion as what percentage of elements of structural steel are recycled or reused. It is observed that nearly 90% of all types of steel structural elements (steel tubes, rebar, light structural steel, profile cladding material, stainless steel) are recycled and reused to an extent of 92-95 %. Also year by year, the percentage of recyclability of steel is increasing significantly, making it the most efficient material in terms of construction, performance, strength and durability, salvage value. Therefore by usage of steel and recycling of steel, resource efficiency is increased.