General Requirements:
1. Engineer should be a technically qualified person in the field of building construction.
2. He should be well versed with rules and regulations of local Nagar Nigam regarding building construction and should never violate them at any stage.
3. He should not undertake any project for which he does not have adequate expertise and resources.
4. He must visit the site before he accepts the offer and check once. There may be a peculiar situation he would have to face, if the offer is accepted by him without checking.
5. At no stage, any short-cut method should be adopted compromising with quality of construction or its planning.
6. He should have good Advisers, who can advise him without any prejudice in case of need.
7. The site should be suitable from Vaastu consideration.
8. Once he accepts a project, he should abide by all commitments that are made by him to his Client at any cost and the project should be materialised in its targeted time.
Preliminary Requisites:
1. He should take ground measurements of the property that he has to deal with physically and compare the existing dimensions with those that are given in the documents. Measurements should be taken in such a way that area of plot or building can be worked out easily.
2. He should protect the property as soon as he takes it over in his charge for its development. No encroachment of land should take place once he takes over charge. A Watchman should be posted at site and boundary poles with covering on the periphery of plot should be provided to protect it particularly in an unlimited locality.
3. Dismantling of existing building if any should be undertaken only after obtaining sanction for construction of proposed building from Nagar Nigam.
4. Soil should be tested for its safe bearing capacity so that the foundation of building can be designed economically and in an efficient way. Depth of sub-soil water level may also be noted down with date.
5. If there are significant undulations in ground levels, exact topography of the ground should be ascertained by taking spot levels in the plot at approximate spots.
6. Existing obstructions are expected to come in the way of the project that should be noted down.
7. The crest level of nearest road to which the approach road shall be connected need to be noted. Possibility of raising existing road level in future may also be considered to decide the appropriate plinth level.
8. How surface drainage network should be planned and connected to existing drainage or otherwise needs be studied.
Planning Requirements:
1. Planning of a building should be according to the rules and regulations of local Nagar Nigam.
2. Planning of building should be need based and should satisfy Client’s requirement primarily.
3. Planning of a building should be functional and available space should be utilised in an efficient manner.
4. Planning of a building should conform to the principles of Vaastu to the extent possible.
5. Planning of building should be aesthetic, pleasant to look at.
6. While planning a building, possibility of future extensions (vertical and/or horizontal) should be kept in view.
7. Planning should be meticulous to achieve best results in comfort, convenience, maintenance and functioning of a building. Number of alternatives should be examined for their merits and demerits before a final option is adopted.
8. At expansion joint, where a combined footing is provided for two adjacent columns proposed side by side, a clear gap of 3” should be kept in between these columns and floor slab at this location, should be extended from both the sides beyond beams to have a clear gap of 1”. This facilitates easy erection and removal of formwork casting of Reinforced Cement Concrete (RCC)s columns.
9. In case of Apartments building with shop line in ground floor, there should be an entry and an exit place for the shop line area.
10. Compound walls with barbed wire fencing must be proposed on all sides of the plot. This gives security and demarcation of plot size as well.
11. While planning, possibility of road widening and/or raising the existing roads in future must be kept in view. No permanent structure should be proposed in such area.
12. Stand-by arrangement must be proposed initially by itself for water supply system, so that breakdown of the working system shall not pose any serious problem in regular water supply especially in case of Apartments building.
13. Network of water supply should be designed in such a way, that each floor and flat shall get the distribution of water even during its supply. It should also cater for possibility of isolating a flat from others to cut water supply, if warranted at any point of time.
14. Network of supply of raw water from borewells and network for supply of drinking water should be completely isolated from each other at any location throughout its run.
15. Fire prevention mechanism should be proposed in planning stage itself.
16. If the location of a building is in an earthquake zone, the planning of a building should cater for the criteria for design of building that is prone to earthquakes.
17. For proposing an Apartments Complex, minimum area of plot is specified by a Nagar Nigam, Builder should see this aspect before he ventures for such building.
18. Floor Space Index (FSI) is another aspect, which dominates planning of such building. This must be kept in view and rigidly followed in planning stage to avoid obtaining of sanction for deviations at a later stage.
19. In case of planning a layout or township, grid orientation should exactly match with North-South, East-West direction. Plots and roads also should be designed accordingly. This will give maximum benefit of Vaastu from orientation point of view.
20. In case of Apartment building, provision of stilt in place of cellar should be preferred. Cellar has inherent drawback of seepage of water during rainy season’s inspite of taking necessary precautions during the construction of retaining walls with cellar floor. As such, cellar should not be proposed to make building maintenance free in this regard.
21. Planning of a building should be done as per specific provisions of National Building Code relevant to the type of building to be constructed.
22. For roof, over staircase room either parapet wall or projection of roof slab beyond the room must be provided. This will avoid seepage of rain water into external walls.
Structural Design Requisites:
1. Structural designs of a building should be prepared by a qualified and an experienced Engineer in design field.
2. Structural design should conform to IS 456-2000 Indian Standard for Plain and Reinforced Concrete-code of practice (fourth revision) and not as per IS 456-1978.
3. While designing a foundation, it should be ensured that the soil strata available within depth of equal one and a half times, the width of footing should not be weaker than the strata for which the foundation size has to been designed.
4. In order to avoid infringement of reinforcement, rods of cross beams, main beams and columns with each other at their junction point, care should be taken in choosing their appropriate dimensions of size and positioning of reinforcement before starting the detailed design calculation.
5. Columns of building should be broadly grouped into three categories:
Internal, External and Corner
Internal Columns can be square / rectangular in shape, External Columns can be or L shaped. Bigger dimensions of column should be parallel to the plane, in which the dominating bending of member shall take place, while it is loaded.
6. Footing size of any column of a building should be designed in such a way that the induced foundation pressure for each column footing is nearly the same. This ensures the avoidance of differential settlement of foundation otherwise; it leads to secondary stresses which are normally ignored in the design of a framed structure.
7. The minimum grade of concrete for reinforced concrete is now M 20 (and not M 15). Hence, the Structural Designs for building should be made for M 20 grade of concrete.
8. While deciding the size of a column of a multi-storied building, it should be ensured beforehand that the adopted size of column is adequate at ground floor as well as at top floor, because vertical load dominates at one location at ground floor level and moment dominates at the other location at top roof level.
9. In the analysis of a frame of a building, due consideration should be made for the eccentric connection of beam to column in plan. The vertical load that is transferred by beam to column may be eccentric to column and the moment induced by the eccentric loading shall be shared by upper and lower columns at this junction.
10. The behaviour of a column with two beams at its top at the same level is different from the behaviour of a column with two beams joining a column from opposite direction at two different levels. In later case analysis of column behaviour, it should be properly done and designed as per its specific requirement.
11. While analysing a frame of a building, the stiffness of floor beams should be worked out as ‘T’ beam or ‘L’ beam or rectangular beam as the case may be. ‘T' beam and ‘L’ beam should not be taken as rectangular beam in the analysis. While designing the T beam or L beam, they should be taken near support as rectangular beam. This approach reduces the share of moment taken by the columns considerably and also results in economy in foundation.
12. Today, in case of plain concrete footing, minimum reinforcement and spacing should be provided as per requirement of solid slab.
13. The minimum number of longitudinal bars provided in a column shall be four in number in rectangular or square columns and six in circular columns and the diameter of longitudinal bar should not be less than 12 mm.
14. While checking deflection under limited state, one should remember the value of partial safety factor for loads that it is 1.0 and not 1.5 which is meant for limited state of serviceability. A deflection criterion is meant for serviceability aspect only.
15. When design imposed load does not exceed three-fourth of design deed load, the loading arrangement shall have sum of design dead load and design at a time. This provision has limited application and is only meant for lighter live loads.
16. The analysis of an R.C.C. continuous frame should be done with centre to centre distance of column as span, but for design purpose the moment computed at the face of support should be reckoned from the face of the support. Therefore, it may be kept in view that criterion for analysis of a framed structure is different from designing criterion and it should be adopted in practice accordingly.
17. In framed structure, where beam members are monolithic at their junction with column, clear span and effective span for designing purpose while in other cases, supports are not monolithic with beams (i.e., brick / stone masonry supports) the design span shall be the effective span. Once, it is monolithic joint, the part of beam or cantilever is anchored monolithically with column and that portion becomes part of the column itself.
18. Clear distinction between braced and unbraced frame should be properly understood by a Structural Designer. Effective lengths of column differ in two cases and their appropriate values should be catered while designing a column. Frame which does not have any lateral sway in loaded condition, is generally taken as braced one and the frame which is free to have lateral sway when loaded is taken as unbraced frame. A symmetrical frame with symmetrical vertical loading shall behave like a braced frame, while a symmetrical with unsymmetrical and/or unsymmetrical vertical loading and / or lateral loading shall behave as an unbraced frame. In an unbraced frame, analysis need correction in bending moments at joints for unbalanced shear force.
19. Any element of water storage R.C.C. structure (which is contact with water) should be designed for safety measures from strength consideration and also for safety against cracking for making it water-tight.
20. Design Engineer should be clear about Global and Local Axis and their mutual relationship while doing analysis. If there is any mistake in this, it shall lead to an erratic result.
21. One should be very clear to know and decide when column reinforcement should be placed on two opposite faces or on all faces of a column. In case of four face reinforcement, number of rods on each face should be the same, whether column is of square or rectangular section.
22. Even in slab design when:
a. Loading on adjacent slab panels and / or when slab thicknesses are different, it should be used in a proper way to adequate the negative reinforcement and common support must be provided.
23. When adjacent spans of slabs are monolithically connected with beam support at bottom and/or slab panels have different loading.
24. In case of a slab located at soffit of a beam, stirrups should take care of hanging action of the slab. If a hoist runs way, joist is attached to the soffit of a beam, adequate number of stirrups should be provided at this location to take up direct pull from the joist in working condition.
25. While designing R.C.C. columns and their foundations a reserve of 10 to 15% must be kept in the design to cater for any contingency to overload the structure in future.
26. For designing an isolated flat or sloped footing of a column bending moment shall be worked out with upward load on trapezoidal area associated with the width of pedestal face at footing top and to work out effective depth of footing.
27. Each column shall be provided with a pedestal to transfer the load to the footing in succession. It is a good practice to provide a column pedestal of such size, so that the pressure of load on column is reduced by 50% in pedestal. The share of bending moment taken by pedestal from the junction of column, plinth beam and pedestal is abnormally heavy due to its high stiffness.
Construction:
1) Atmost care should be taken during construction of following elements of a building:
a) Foundation: Proper consolidation of soil should be done by ramming most soil before concreting.
b) Junction of beams and columns: Proper placement of concrete around reinforced steel is a must to get best results. Therefore, while designing these, care should be taken that with arrangement of steel taken that with arrangement of steel at junction sufficient space is available for insertion of concrete and mechanical vibrator at this location. Use of 12 mm size aggregate and / or use of quality plastisizers in concrete around steel bars.
c) Toilets and Bathrooms: One should be very careful to make flooring of the location water leak proof. Even a very fine crack or cleavage left in this will be sufficient to result in leakage. Hence, strict supervision is required while carrying out work in toilets and bathrooms. Sealant and water resistant material must be used and placed in position in a compacted way to avoid any void for seepage of water. Proper slope for natural drainage toward drain is a must.
d) Terrace: Terrace is a head protection of a building against sun, its heat and rain water. Thermal insulating material like brick bat coba should be used to insulate transfer of heat from sun. Proper drainage slope (preferably1 in 60) must be given to terrace to make it leak proof. Drainage scheme should be decided at the planning stage itself.
e) If reinforcement bars are extended above terrace to use them for future floor, they must be embedded in a lean concrete pedestal and should never be left bare inviting corrosion. Their length should not be less than the developmental length. These lengths must be indicated even in detail drawing.
f) Vertically of columns should be ensured before casting them. Any misalignment in vertical will cause additional stresses in concrete members.
2. Galta must be provided at the corner junction of parapet wall and terrace. This prevents entry of rain water into the joint at the junction.
3. All precautions needed for quality work should be taken at site. Requirement of quality assurance should be looked after, before the start of any activity at site.
There are number of items under this head and covers a wide range such as:
i. Quality of materials to be used
ii. Storing and handling of materials
iii. Mixing of materials
iv. Workmanship during execution
v. Erection and removal of formwork
vi. Placement of reinforcement and quality of concrete mix.
vii. Curing of masonry and concrete work and
viii. Quality of supervision work. Etc.
4. 10 to 12 mm deep grove should be provided in plaster of panel wall at its junction with beam and column. This will arrest the possibility of formation and extension of any crack junction of the two.
5. All projections beyond outer walls must be provided with groove of drip course to arrest approach of rain dropping water towards walls.
6. Rain down pipes should not butt against wall surface. There should be a clear gap between the two.
Rough stone payment in the compound area of a building around should have recess of 1 to 1 ½ widths at 600 to 750 mm interval in both directions to allow rain water to penetrate through them. These recesses may be lined in grass and this will help in the yield of water input in borewell and open walls. Rain water can be harvested even in this way.
No comments:
Post a Comment
Your Comment on this box