IS Seismic Evaluation, Repair and Strengthening of Masonry Buildings - Guidelines. byBureau of Indian Standards. Publication date. The provisions of this standard are applicable for buildings in seismic Zones III to V of IS (Part –. 1): These are based on damaging seismic. IS - Download as PDF File .pdf), Text File .txt) or read online. yjhfgj.
|Language:||English, Spanish, Dutch|
|Distribution:||Free* [*Register to download]|
Download as PDF, TXT or read online from Scribd. Flag for .. IS Indian Standard REPAIR AND SEISMIC STRENGTHENING OF BUILDINGS. medical-site.info Comments. Similar IS Code / Standards. Recent; Popular; Featured. IS - Based on Draft First Revision of IS (June ) by. Padmashree Dr. Anand S. Arya, FNA, FNAE. Professor Emeritus, Deptt. of.
Alternatively, chemical anchors bonded in drilled holes through polymer adhesives can be used. Therefore, all cracks must be located and marked carefully and the critical ones fully repaired either by injecting strong cement or chemical grout or by providing external bandage.
The techniques are described below along with other restoration measures. The procedure is as follows see Fig.
The centre-to-centre spacing of these ports may be approximately equal to the thickness of the element. After the sealant has cured, a low viscosity epoxy resin is injected into one port at a time beginning at the lowest part of the crack, in case it is vertical, or at one end of the crack, in case it is horizontal. The resin is injected till it is seen flowing from the opposite sides of the member at the corresponding port or from the next higher port on the same side of member.
The injection port should be closed at this stage and injection equipment moved to the next port and so on. The smaller the crack higher is the pressure or more closely spaced should be the ports so as to obtain complete penetration of the epoxy material throughout the depth and width of member. Larger cracks will permit larger port spacing depending upon width of the member. This technique is appropriate for all types of structural elements beams, columns, walls and floor units in masonry as well as concrete structures.
In the case of loss of bond between reinforcing bar and concrete, if the concrete adjacent to the bar has been pulverised to a very fine powder this powder will block the epoxy from penetrating the region. It should be cleaned properly by air or water pressure prior to injection of epoxy.
IS : The procedures may be adopted as follows: a The loose material is removed and replaced with any of the materials mentioned earlier, that is, expansive cement mortar quick setting cement see Fig.
This reinforcement could be covered by mortar to give further strength as well as protection to the reinforcement see Fig. Then it may be covered with plaster or micro-concrete see Fig. This element can be repaired by replacing the old portion of steel with new steel using butt welding or lap welding. Splicing by overlapping will be risky. If repair has to be made without removal of the existing steel, the best approach would depend upon the space available in the original member.
Additional stirrup ties are to be added in the damaged portion before concreting so as to confine the concrete and enclose the longitudinal bars to prevent their buckling in future. In some cases, it may be necessary to anchor additional steel into existing concrete. A common technique for providing the anchorage uses the following procedure: A hole larger than the bar is drilled. The hole is filled with epoxy expanding cement or other high strength grouting material. The bar is pushed into place and held there untill the grout has set.
The weathered or rotten wood should first be removed. Nails wood screws or steel bolts will be most convenient as connectors. It will be advisable to use steel straps to cover all such splices and joints so as to keep them tight and stiff.
Where possible, they should be replaced with corrugated iron or asbestos sheeting. Non-brittle material, like hessian cloth, bamboo matting or light ones of foam substances, may be substituted. Figures 2 and 3 illustrate one of the methods for pitched roofs without trusses. Timber elements could be connected to diagonal planks nailed to them and spiked to an all round wooden frame at the ends.
Non-brittle material. It will be advisable to use steel straps to cover all such splices and joints so as to keep them tight and stiff.
The first two cases refer to a T-junction whereas the third to a corner junction. A common technique for providing the anchorage uses the following procedure: The hole is filled with epoxy expanding cement or other high strength grouting material.
Nails wood screws or steel bolts will be most convenient as connectors. This element can be repaired by replacing the old portion of steel with new steel using butt welding or lap welding.
The increase of shear strength which can be achieved in this way is considerable. The two plates on either side of the wall should be connected by galvanized steel rods at a spacing of about to mm see Fig 9. NOTE — The pressure need for grouting can be obtained by gravity flow from superelevated containers.
First water is injected in order to wash the wall inside. This would strengthen the walls as well as bind them together.
Strength of shear walls is achieved by providing vertical steel at selected locations as described in 7. Opposite parallel walls can be held to internal cross walls by prestressing bars as illustrated above the anchoring being done against horizontal steel channels instead of small steel plates. The steel channels running from one cross wall to the other will hold the walls together and improve the integral box like action of the walls.
As a variation and for economy in the use of materials. Note that. Prestressing is also useful to. This can be achieved by a use of prestressing b providing horizontal bands. The easiest way of affecting the precompression is to place two steel rods on the two sides of the wall and stretching them by turnbuckles.
In jack-arch roofs.
Damaged portions of the wall. In thick walls. Loss of prestress due to creep relation and temperature fall shall be duly considered. Alternatively masonry buttresses or pillasters may be added externally as shown in Fig. The wires will run on both sides of the web Desired quantity of longitudinal and transverse steel may be added in each case.
For holding the stirr-up in this case. Reinforced concrete beams can also be strengthened by applying prestress to it so that opposite moments are caused to those applied. Alternatively it can be jacketed as shown in Fig. The desired strength and ductility can thus be built-up.
In all cases of adding new concrete to the old concrete. Jacking operations may be needed in this process. These rods should also be dipped in epoxy adhesive formulations before placing in position. These will also bind the various wall footings and may be provided on both sides of the wall see Fig. The ends of the additional steel are to be anchored in the adjacent beams or columns as the case may be.
Some alternatives are given below for preliminary consideration of the strengthening scheme: In addition to this. NOTE — To avoid disturbance to the integrity of the existing wall during the foundation strengthening process proper investigation and design is called for. In any case. Also to the existing steel.
Such bond could be created by the application of suitable epoxy adhesive formulations on the prepared old concrete surface. University of Roorkee. Calcutta Irrigation Department.
Hyderabad Department of Earthquake Engineering. BIS Continued on page 22 Bombay National Buildings Organization. New Delhi Tata Consulting Engineers. Govt of Maharashtra. New Delhi Nuclear Power Corporation. Nasik Engineers India Ltd. New Delhi North Eastern Council. Army Headquarters. New Delhi Geological Survey of India.
New Delhi Railway Board. Department of Surface Transport Roads Wing. New Delhi Ministry of Transport. Shillong Indian Society of Earthquake Technology. Madras Central Public Works Department. Roorkee Indian Meterological Department. New Delhi Director General. Pune Department of Atomic Energy. Roorkee Shillong Indian Institute of Technology. New Delhi National Buildings Organization.
Madras DR P. Roorkee DR B. Gauhati Publing Works Department. Government of Himachal Pradesh. CED Department of Earthquake Engineering. Lichenstein et al. Thus, escalating cannabis use versus stable use during this period may impede the strengthening of the corticostriatal connections that is linked to negative consequences.
The usual caveat applies here—that is, whether this decreased functional connectivity predated escalated cannabis use or resulted from it is unknown.
Thus, the integrity of the reward network can be used to determine individuals who may later develop problems related to cannabis use. Equally important to determining mechanisms that lead to problematic use is understanding the individual differences that influence these mechanisms.
Low SES may be a proxy for both environmental and genetic vulnerabilities that have similarly been associated with dysfunction in the reward network.
Early life stress has been postulated to disrupt the maturation of the reward system.