COST-EFFECTIVE RETROFITTING MEASURES FOR KASHMIR VALLEY

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1 ISET GOLDEN JUBILEE SYMPOSIUM Indian Society of Earthquake Technology Department of Earthquake Engineering Building IIT Roorkee, Roorkee October 20-21, 2012 Paper No. E002 COST-EFFECTIVE RETROFITTING MEASURES FOR KASHMIR VALLEY Zahid Mohammad Mir 1, Mohammad Zahid Akhtar 2 and Dr. A.R. Dar 3 1 B-Tech, NIT Srinagar, zahidmir7@gmail.com 2 B-Tech, NIT Srinagar, mdzahidakhtar786@gmail.com 3 Head of Department, Civil Engineering Department, NIT Srinagar, abdulrashid@nitsri.net ABSTRACT The Kashmir valley falls in the active Himalayan belt and is one of the most earthquake prone regions of the world. In the past decade Kashmir valley has witnessed austere earthquakes with Magnitudes hitting up to (M 7.2) in 2005 which resulted in huge loss of life as well as enormous economic loss. The maximum fatalities were due to collapse of non-engineered constructions, a myriad of which happen to be masonry structures and thus aggrandized the problem. Unfortunately, the seismic risk in developing countries like ours keeps on increasing because the basic principles of earthquake resistant design and codal guidelines brought out by BIS are often not being followed in practice. The reasons are unawareness, apprehension of additional cost and intentional ignorance. New structures can easily be made earthquake resistant, however, the existing building which need to be saved, calls for retrofitting. The paper aims at in depth study of existing lifeline structures (Health centers, schools etc.) in Kashmir valley and then applying scientific and technical know-how for structural evaluation followed by adequate, easily implementable, economic retrofitting measures. The aim is also to make a user friendly retrofitting manual for common people, along with already completed Kashmir valley based lucid case studies so that it becomes easily adoptable by common man, thereby saving people from consultant charges, explicating cost-comparison, and most importantly promoting engagement and awareness of earthquake safety and retrofitting. The paper contains detailed field work results and case study of major Health center and application of easy, simple retrofitting methods are proposed. INTRODUCTION Past earthquake statistics have shown us how extremely vulnerable the buildings are in the Kashmir valley. It also brought to light that when people build houses they do not seem to be aware of the threats posed by earthquakes. As it has observed in earthquake records, people are unable to assess the root cause of earthquake destruction. The 2005 earthquake shook the confidence of Kashmiri`s in local building material and even in the techniques they had been using to build houses for centuries. Immediate reaction has been a strong desire to abandon traditional architecture and building systems and adopt cement and steel bases construction in the local context. Some structures were completely destroyed by the earthquake. But many more were left standing, either damaged to varying degrees or with no damage at all. People in slightly damaged houses are

2 likely to simply to patch up the damage and continue living in them. But those in moderately damaged houses often think that these are beyond repair and this want to demolish them and rebuild them. Kashmir has experienced earthquakes almost regularly during the course of its evolution and will continue to do so. Our traditional earthquake resistant architecture of Dhajji-Dewari and Taak is long gone and such have replaced timber which was an essential building material with concrete. Findings of a leading scientist Roger Bilham of Colorado University issued a severe earthquake warning for Kashmir Valley. The scientist on the basis of GPS data compiled has conferred that a Magnitude 9 earthquake is eminent originating from the Zanskar Mountain Range. The scientist s findings suggest massive loss of life given existing building codes. The reason he tends to suggest a loss of 3 lakh lives in the Valley is his belief on inadequate safety measures of existing infrastructure, codal provisions followed, disaster mitigation and disaster mitigation policies implemented. In such a scenario it becomes very important for the people living in this part of the world to have their houses safe guarded against such ground shakings. It is surprisingly easy and cheap to produce realistic resistant to typical seismic activity in building through proper Retrofitting schemes. As such this study envisages to address the serious and widespread problem of seismic vulnerability of buildings in the Valley with special attention to Hospitals, college and School buildings which has been assigned an importance factor 1.5 according to IS For this purpose, Govt. Chest Diseases Hospital, Srinagar, has been selected as case study site. In this study vulnerability assessment of the said structure has been carried out and appropriate economic retrofitting measures have been proposed. This paper presents a very placid and pragmatic coverage of the applicability of earthquake vulnerability assessment and retrofitting guidelines as prescribed by BIS codes. VULNERABILITY ASSESSMENT Vulnerability assessment based on visual inspection was carried out for a myriad of important buildings in the Kashmir valley by organizing regular field visits and taking records at each site. Based on the data collected, buildings with considerably higher seismic vulnerability were shortlisted and studied in detail. The seismic vulnerability of a building depends upon the choice of building materials, the construction technology adopted, and the quality of the construction practice. In Kashmir, many types of construction practices are used with a variety of materials. These include local materials such as mud, straw, wood, stone, and bricks. Industrial materials such as concrete blocks, cement and steel are now also commonly used. People in the Kashmir valley have an apprehension that including proper seismic concepts in the construction will increase the construction cost considerably. People are too bold not to even consult a proper civil engineer before construction, which ultimately results in vulnerable structures posing a threat to life as well as to the property. The vulnerability of buildings in Kashmir can thus be very high, both with local and newly introduced materials. In the absence of good construction practices and engineering inputs even new buildings may be at risk. It is therefore very important to check the earthquake vulnerability of all existing buildings of mixed traditional and modern construction in Kashmir; whether damaged or undamaged, since all of these are located in Seismic Zones IV or V. This paper thus brings out easy to apply, economic retrofitting techniques for the use of a people of Kashmir. Practical application of such retrofitting techniques have been explained and illustrated precisely in the two case studies that follow.

3 CASE STUDY: GOVERNMENT CHEST DISEASES HOSPITAL, DAL GATE, SRINAGAR. The Chest Hospital building Consists of various blocks like the Ward blocks, administrative blocks, Record section, Emergency ward, isolation ward etc. Some of the blocks are as old as 100 years and suffer serious visible damages and cracks, while some buildings like Administrative Block in comparatively young (around 20 years old) as shown in (Fig 1). PRELIMNARY EVALUATION:- Preliminary evaluation was carried out and following data was obtained (table Fig 1: View of Govt. Chest Diseases Hospital, Srinagar. 1). The data was processed to assess the vulnerability of the structure. The checklist and damage assessment is done according to handbook on seismic retrofit of buildings IITM. Check List for Preliminary Evaluation of Masonry Buildings:- {Ref. handbook for seismic retrofit of buildings IBC. IITM} Building Name: Government Chest Diseases Hospital Use: Hospital Address: Dal Gate, Srinagar Number of Storey: 2 (for most of the blocks) Year Built: 1990 s Foundation Type: Strip Footing Roof Type: Inclined Sheeting Floor Type: Concrete Flooring Structural Components:- Beams, Slabs Wall Type: RRSM Slab Thickness: -150 mm R/F Thickness of Wall: 300 mm Mortar Type: Lime Vertical R/f bars: -Nil Seismic bands : - Nil

4 Table 1: Format of Preliminary Data Collection of Buildings PROBLEM 1: LARGE VERTICAL CRACK IN WALL AT MID-WAY (GRADE 3 CRACK) Fig 2: G3 Grade Crack in Wall DESCRIPTION AND CAUSE OF THE PROBLEM:- Large vertical crack (G3 grade i.e mm wide) was seen in one of the buildings of the chest hospital. The crack was almost in the middle of the wall and was extending from roof to the plinth (Fig 2). A wall can be assumed to behave like a fixed beam as it is fixed at corners with other walls. As a result maximum sagging moment generally occurs at the mid-way of the walls. This can be a probable reason for the above type of the problem. The h/t and l/t ratios are as follows: Thickness (t) Height (h) Length (l) h/t l/t 300 mm 3 m 8 m REMEDIAL RETROFITTING MEASURES:- 1. Make a V notch along the crack; clean it with a wire brush. 2. Clean crack with water to remove the fine, loose particles inside the crack. 3. Prepare masonry surface on both faces of the wall for fixing200 mm wide Ferro cement splices across the crack as shown in the diagram, by removing the plaster, raking the joints up to 12 mm depth, and cleaning it with water, extending on both sides of the crack to a minimum of 450 mm length.

5 4. Fill the crack with 1:3 cement mortar (non-shrink cement: fine sand) with just enough water to permit pushing in of mortar as far in as possible, from both faces of the wall. 5. Install the 150 mm wide 25x25 14 gauge galvanized welded wire mesh (WWM) (2.03 mm diameter) with 100 mm long wire nails inserted at spacing no greater than 300 mm in a staggered manner. 6. A gap of 10 mm must be maintained between the mesh and un-plastered wall. 7. Plaster over the mesh with two 12 mm coats of 1:3 cement plasters. 8. Cure it with water for 15 days. PROBLEM 2:- G1 GRADE CRACKS AT MANY PLACES IN THE BUILDING (a) (b) (c) Fig. 3: Distresses: Fine cracks in various walls.

6 a) DESCRIPTION AND CAUSE:- These G1 grade cracks (<1mm in width) in plaster are one-dimensional and are only measured in length (Fig 3). The reason might be when walls are held at corners by the adjacent walls and in the course of an earthquake when the shaking is perpendicular to a wall, its portion away from the corner will shake the most. Such shaking can result in vertical cracks near the mid-length of the wall. The longer the wall the more it will shake, and the greater will be the chances of it cracking and suffering damage. Similarly, if a wall is extra high it will shake more. Such a wall will develop horizontal cracks when shaken. a) REMEDIAL RETROFITTING MEASURES:- Sealing of cracks using cement mortar should be carried out in the following steps. 1. Make a V notch along the crack. 2. Clean the crack with a wire brush. 3. Fill the gap with 1: 3 cement mortars. Finish the restored part to match the surrounding wall surface. PROBLEM 3: POSSIBLE POUNDING EFFECTS BETWEEN TWO PARTS OF THE BUILDING Fig 4: Possibility of pounding between two adjacent buildings. DESCRIPTION AND CAUSE: A new part of the building was constructed on offsets taken from the older part. Although separation joint was provided between the two building parts but adequate space to avoid pounding was not provide (Fig 4). The roof level of the new part is at the mid was of the

7 walls of the older part. In such a case, pounding between the two parts can result in severe damage. REMEDIAL RETROFITTING MEASURES: The possible remedial measure in such a scenario is to remove a vertical layer of brick work in between the building parts to account for possible pounding effects. However, due precautions, such as, not more than exactly one brick layer should be removed in a manner that no damage should done to the walls, to preserve their structural integrity. PROBLEM 4:- DAMAGE TO INFILL IN DHAJJI WALLS Fig 5: Damage to infill walls DESCRIPTION AND CAUSE: Infill in dhajji walls were seen to be damaged at many places in the buildings. The infill bricks were coming out at many places like the one shown in Fig 5. Damage to infill in Dhajji walls is accepted on account of possible energy dissipation in an event of an earthquake to conserve the integrity of wall as a whole. POSSIBLE REMEDIAL MEASURES: The damage infill should be replaced with fresh infill brick work. CONCLUSION: This study is convergent on the common types of failures/cracks observed in the masonry and Dhajjidewari construction of Govt. Chest Diseases Hospital. Although a lot of latest techniques are available

8 today such as use of carbon reinforced polymers (CRP), glass reinforced polymers (GRP), aramidic reinforced polymers (ARP), seismic wallpapers etc but the cost of application of such techniques in a place like Kashmir valley is very high due to local constraints such as, lack of skilled labour, materials and poor economic conditions. People already have a tight-fisted approach towards latest construction practice as a result people can barely resort to such retrofitting techniques. On the other hand, the proposed techniques use locally available materials and do not need the involvement of highly specialized skilled labour. A normal Kashmiri mason is enough to do a commendable job using such techniques. Further this paper also aims to provide a practical vision to such cheap retrofitting techniques by discussing case study of the Hospital block. It is hoped that the material presented in this paper will be useful in enhancing the understanding of masonry related earthquake engineering problems and use of seismic retrofitting. REFERENCES: 1. A. Chakrabarti (2008), Handbook on Seismic Retrofit of Buildings, Hamid A., Mahmoud A. and Abo El Maged S. (1994), Strengthening and repair of unreinforced masonry structures: state-of-the-art, 10th IB2MaC, Calgary, Canada, Hugo Bachmann (2003). Seismic conceptual design of buildings- Basic principles for engineers, architects, building owners, and authorities, Karantoni F. and Fardis M. (1992), Effectiveness of seismic strengthening techniques for masonry Buildings, ASCE, 118(7), M. ElGawady (2004), A Review of Conventional Seismic Retrofitting Techniques for URM, 13th International Brick and Block Masonry Conference Amsterdam July Matthys H. and Noland L., (1989), proceedings of an international seminar on Evaluation, strengthening and retrofitting masonry buildings, TMS, Colorado, USA. 7. Rama Lakshmi (2011), Kashmir Underwater? A Colorado geologist thinks it is possible,