5__ by ides editor

Short Paper Proc. of Int. Conf. on Structural and Civil Engineering 2011

Experimental Study on the Effect of Diagonally Loaded Masonry Infilled RCC Frames Subjected to Ultimate Loads P. Sachithanantham1 P. Dayakar2 and Dr. K.V.B. Raju3 1

Bharath University / Department of Civil Engineering, Chennai, India. E-mail:sachu_civil@yahoo.co.in

Bharath University / Department of Civil Engineering, Chennai, India. E-mail:dayakarpitti@yahoo.co.in 3

Sakthi Mariamman Engineering College, Tandalam, India. E-mail:kvbraju@hotmail.com

sieve analysis are conducted for fine aggregate and impact test, crushing test are conducted for coarse aggregates. “Ref[2]” Tests such as fineness, initial setting time and consistency test are conducted on cement.

Abstract - During the construction of different phases of building construction, framed structures are frequently used due to the ease of construction and rapid progress of work. Usually in the analysis of multi-storeyed building frames the effect due to the infill walls usually in brick work is not considered. In this paper an attempt is made to study the effect of reinforced cement concrete frames with masonry infill walls subjected to ultimate loads. The specimens of reinforced cement concrete frames with 0%, 55%,65%, 75%,85%, 90%, 95% and100% infill are prepared with concrete of grades M20 and M25. The infill masonry walls are made with brick work with cement mortar 1:5. The mix design of concrete is done by using IS methods. Preliminary tests for concrete constituents are conducted. The specimens are moist cured for 28 days. Specimens are subjected to ultimate loads till failure. Observations are recorded. Conclusions are made based on the experimental investigations.

II. METHODOLOGY A. Materials Ordinary Portland Cement 43 grade is used for the investigation. Locally available fine and coarse aggregates are used. Frame specimens are prepared with concrete of grades M20 and M25 for which mix proportion are arrived as shown in table 1 using IS method. Basic tests are conducted as per IS standards on the materials used for concrete, such as specific gravity, fineness, consistency, and initial setting time for cement. For fine and coarse aggregates tests such as sieve analysis, specific gravity, impact value and crushing value are conducted as per standards. “Ref[2] [3]” and results are tabulated in table 2, 3 and 4. For fine and coarse aggregates tests such as sieve analysis, specific gravity, impact value, crushing value and abrasion value (Los Angeles) are conducted as per standards “Ref [2] [3]” and results are tabulated.

Index terms - infill wall, laterally loaded rcc frames

I. INTRODUCTION In the analysis of multi-storeyed building frames the effect due to the masonry infill walls constructed usually in brick work with appropriate mortar ratio is not considered. When the reinforced concrete frames are subjected to only gravity loads then the procedure may hold good but during the action of lateral loads such as wind and seismic loads the design of reinforced cement concrete frames with and without masonry infill play a major role. Murty and Jain observed the beneficial effect of masonry infill in energy dissipation and overall ductility capacity of building system. They have concluded that due to infilling, the stiffness increases more than 4 times, the strength increases more than 70%, the ductility increases by 4 times and also concluded that the inclusion of masonry infill drastically reduces the ductility demand on the RCC frames. “Ref[1]” In this paper attempt is made to study the effect of reinforced cement concrete frames with masonry infill walls subjected to ultimate loads. To determine the effect of brick masonry infill wall in reinforced frames with infill walls of different percentage openings are taken for the study. Reinforced concrete frame specimens of M20 and M25 are prepared for which the mix design is done by using IS method. Preliminary tests such as specific gravity, water absorption, © 2011 ACEE DOI: 02.SCE.2011.01. 5

B. Mix Design Concrete used in the investigation is designed in accordance with IS 10262 “Ref [4]” Design Stipulations Characteristic Compressive Strength required in the field at 28 days - 20 N/mm2and 25 N/mm2 Maximum size of aggregate - 10mm (Angular) Degree of workability - 0.85 (Compacting Factor) Degree of Quality control - Good Type of Exposure - Mild Test Data for Materials Cement used - OPC – 43 grade Specific gravity of Cement - 3.15 Specific gravity of coarse aggregate- 2.66 Specific gravity of Fine aggregate - 2.58 Water absorption Coarse aggregate - 1% 6

Short Paper Proc. of Int. Conf. on Structural and Civil Engineering 2011 75mm centre to centre as shown in fig. 1. The reinforced concrete frame specimens of M20 and M25 grade with various masonry infills of 0% 55%,65%, 75%,85%, 90%, 95% and 100% with brick masonry in 1:5 cement mortar are prepared and moist cured for 28 days before testing as shown in fig.2 and fig. 3.

Fine aggregate - 2% Free surface moisture Coarse aggregate - Nil Fine aggregate - 1.5% Sieve analysis Coarse aggregate -Confirms grading of IS 383 - 1973 Fine aggregate - Confirms zone II The design stipulations for M20 and M25 grade concrete is given in table I. TABLE I DESIGN MIX PROPORTION

C. Experimental Investigations The following tests are conducted on cement, fine aggregate and coarse aggregate and the results are tabulated in table II, table III and table IV respectively. TABLE II TEST ON CEMENT

Figure 1. Formwork and reinforcement for frame specifmens

TABLE III TEST ON FINE AGGREGATES Figure 2. Reinforced cement concrete frame with 90% masonry infill

TABLE IV TEST ON COARSE AGGREGATES

Figure 3. Reinforced cement concrete frame with 100% masonry infill

D. Experimental Setup and Testing The self straining load frame and the loading jack along with proving ring are arranged in such a way to apply the concentrated force diagonally on the specimen as shown in fig 4, fig.5 and fig.6. Care is taken to avoid eccentricity during loading. Masonry infilled reinforced cement concrete frames of 0%, 55%,65%, 75%,85%, 90%, 95% and100% infill are

The frame specimens are prepared to suit loading arrangements and test facilities. The outer to outer dimensions of the frame specimen are 750mm x 750mm, with the cross sectional dimension of 75mm x 75mm as shown in fig.1. The main reinforcement of 8 no. of 4mm diameter bars with stirrups of 4mm diameter are provided at a spacing of ÂŠ 2011 ACEE DOI: 02.SCE.2011.01. 5

Short Paper Proc. of Int. Conf. on Structural and Civil Engineering 2011 subjected to ultimate loads till failure. Visible crakes first appeared at the joints and propagated along the diagonals. The ultimate loads are tabulated in table V.

TABLE V ULTIMATE LOAD ON FRAME SPECIMENS

Figure 4. Reinforced cement concrete frame with 0% infill during testing

Figure 5. Reinforced cement concrete frame with 90% infill during testing

Figure 7 Relation between Ultimate load and percentage of masonry infill-M20 grade

From fig.7 and fig 8, it is observed that the ultimate load increases with the increase in percentage of brick masonry infill in reinforced cement concrete frames of M20 and M25 grades.

Figure 6. Reinforced cement concrete frame with 100% infill during testing

III. RESULTS AND DISCUSSIONS Table V shows the relation between the ultimate loads and percentage of masonry infill in reinforced cement concrete frames. A plot is made between ultimate loads and percentage of infill as shown in fig. 7 and fig 8 for frame specimens of M20 and M25 grade respectively.

ÂŠ 2011 ACEE DOI: 02.SCE.2011.01. 5

Figure 8 Relation between Ultimate load and percentage of masonry infill -M25 grade

Short Paper Proc. of Int. Conf. on Structural and Civil Engineering 2011 REFERENCES

IV. CONCLUSIONS The following conclusions are drawn from the test results. i) It is concluded that the ultimate load increases with the increase in percentage of brick masonry infill in reinforced cement concrete frames of M20 and M25grades. ii) It is also concluded that there is an increment of 523% and 570% for 90% and 100% masonry infill with respect to rcc frame with no infill respectively for M20 grade. iii) It is conclude that there is an increment of 505% and 561% for 90% and 100% masonry infill with respect to rcc frame with no infill respectively for M25 grade.

[1] Murty, CRV and Jain, SK (2000) “Beneficial influence of masonry infill wall on seismic performed on reinforced concrete frame building”. The 12 th world conference on earthquake engineering # 1790 on CD-ROM , New Zealand pp 29-43. [2] IS: 2386 (Part I – IV) - 1963, “Methods of Test for Aggregates for Concrete”, Bureau of Indian Standard, 1963. [3] IS: 383-1970, Coarse and fine aggregate from natural sources for concrete, Indian Standards Institution, 1970. [4] IS: 10262-1982, recommended guidelines for concrete mix design, Indian Standards Institution, 1982.