ML20011A469
| ML20011A469 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 09/30/1981 |
| From: | COMPUTECH ENGINEERING SERVICES, INC. |
| To: | |
| Shared Package | |
| ML19312F019 | List: |
| References | |
| IEB-80-11, R553.13, TAC-42896, TAC-42897, NUDOCS 8110130449 | |
| Download: ML20011A469 (10) | |
Text
{{#Wiki_filter:~ COMPRESSIVE STRENGTH OF PRISMS AND CONCRETE BLOCKS Prepared for Point Beach Nuclear Power Plant, Units 1 and 2 WISCONSIN ELECTRIC POWER COMPANY Milwaukee, Wisconsin Prepared by COMPUTECH ENGINEERING SERVICES, INC. Berkeley, California l I September,1981 l l REPORT NO. R553.13 8110130449 01100705000266PDR PDR ADCCK G
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TABLE OF CONTENTS 1 INTRODUCTION . . . . .. .. 1 2 NUMBER Ai4D TYPE OF PRISM AND BLOCK SAMPLES . ... . . . 1 3 METHOD OF EXTRACTION . . .. . . . . 2 4 COMPRESSIVE TEST METHODS . .. . ... 3 5 RESULTS OF COMPRESSIVE TESTS . . . . ..... ... . 3 6 CONCLUSIONS . . . .. . .. 3 '
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1 INTRODUCTION The Nuclear Regulatory Com:nission (NRC) staff on June 9-11. 1981 reviewed the criteria and calculatione performed on IE Bulletin 80-11 " Masonry Wall Evaluation" for the Point Beach Nuclear Power Plant. One of the action items that resulted from the review meeting was the performance of masonry prism and block ttists to validate the use of the special inspection allowable stresses used in the criteria. Computech Engineering Services Inc (CES) Report No. 553.01. submitted to the NRC on July 15. 1981. prior to testing. outlined the methods 1%t would be used to obtain the required information. This report. prepared after the tests were performed. describes in detall the methods that were used. the number of samples that were actually obtained and provides a summary of the test results. The extraction and testing of the samples was performed by Soll Testing Services of Wisconsin and the detailed test results are given in their report STS Job. 11297 which is included as Appendix A to this report. 2 NUMBER AND TYPE OF PRISM AND BLOCK SAMPLES Three prism and two blocks samples were extracted by the method described in the next section from the following walls: 1 ) Stairwell - Unit 1 - 1 Wythe. 6* Thick
- 2) Stairwell - Unit 2 - 1 Wythe. 6" Thick
- 3) Wall 68 - 1 Wythe. 8* Thick Tha prisms were three units or approximately 24 inches high and 8 inches long.
The two masonry units from each wall were 16 inches long and 8 inches high
- see Appendix A for exact dimensions.
In Computech Engineering Services (CES) Report No. 553.01 it was stated that prism and block samples would be extracted from Wall 150, 65 and 104 in addition to one stairwell wall and Wall 68. The reasons that samples *;ere not tested from Walls 150. 65 and 104 are as follows: Wall 65 - This wall contained both horizontal and vertical reinforcement. Consequently there were limited locations for removing both proms and block sarra!es. Pfortunately both the prism and block samples that were removed from the wall were constructed from bond beam units. These units wore unsuitable for coth prism and block tests. Cor.sequently the samples removed were not tested and it was not feasible to ext-act additionel samples because of the location of the reinforcement. Walls 150 and 104 - Both walls were of multiwythe interlock construction. This form of construction is different to normal multiwyhte construction. which consists of 2 or more wythes laid adjacent to each other and bonded together with ties and/or a collar joint. The interlock form of construction does not have a continuous vertical collar joint and consists of alternating layers of different size units interlerked. Photos of Wall 104 are shown in Figs.1 and 2. The top layer consists of three different types of units. The units on the front edge of the wall and shown in 1
Fig. 1 are 6 inches wide by 16 inches long by 8 inches high. The units on the back edge are 16 inches wide by 12 inches long by 8 inches high. The unit on the left back edge of the wall is 8 inches wide by 12 inches long by 8 inches high. The second layer of the wall consists of the same units shown on the top layer but reversed so that the bigger sized units ere on the front side of the wall as shown in Fig. 2. This pattern then alternates down the height of the wall. leading to a vertical stack of interlocked units. With this pattern of interlocking it was impossible to extract a prism sample from the wall that contained two webs of a masonry unit. because the wider units did not have an intermediate web. Consequently no samples were extracted from Walls 150 and 104. Since it was not possible to obtain prism and block samples from three of the five walls stated in CES Report No. 553.01, three prism and two block samples were taken from the wall of the stairwell in Unit 2. In total there were 9 prism and 6 block tests from 3 different walls. This compares to the original goal of 5 prism and 5 block tests from 5 different walls. 3 METHOD OF EXTRACTION A high speed diamond saw cutter was used to cut both the prism and block samples from the wall. A guide track. as shown in F9 3. was bolted to the wall adjacent to the required horizontal or vertical cut. The diamond saw was mounted on the track, as shown in Fig. 4. and the required cut was made. The diamond saw was very effective and caused very httle vibration in the wall. After each cut, wooden wedges were placed along the cut, as seen in Fig.
- 3. to ininimize vibration in the cut portion of the wall.
In total five cuts were made in each wall - two vertica' and three horizontal. The two sections of the wall that were removed are shown in Fig. 5. and consisted of one section that was 3 units high and 1.5 units long while the other was 2 units high and 1.5 units long. 'ue wall with the samples removed is shown in Fig. 6. Upon removal from the wall, the section that was 2 units high was cut along the horizontal joint with a masonry saw and the half units were removed. This then left two full size masonry units that were used to determine the compressive strength of the block units. The three high section was cut vertically along the head joints, resulting in th,ee prisms that had a H/d ratio of approximately three. The method of extrac:lon was successful. although it could only be performed on walls where there was ample cleararice both on and adjacent to the wall. The required clear space on both sides of the wall was approximately 6 ft vertically and 4 ft 6 in horizontally. The diamond saw required a clear working space of approximately 36 sq ft adjacent to the wall. These limitations were not a problem for the f' Jr walls from which samples were taken. 2
4 COMPRt-SSIVE TEST METHODS Each prism compressive test was performed in accordance with apphct;ble sections of ASTM E-447-74. The stress-strain curve was not required a:, part of the test procedura. Each masonry unit compressive test was perforrr.a0 in accordance with applicable sections of ASTM E-140-75. The details,d resu ts of each test are given in Appendix A. 5 RESULTS OF COMPRESSIVE TESTS A summary of the test results is given in Table 1. The compressive strength f'm is based on the Uniform Building Code correction factors for prism tests. Section 2404 states that for a H/d ratio of 3 the compressive strength I'm shall be taken as the compressive strength of the tested prisms multiplied by 1.20. The average H/d ratio for the prisms was approximate! 3. It was stated in CES Report No. 553.01 that the value of f'm to be used in the criteria for IE Bulletin 80-11 shall be the lowest of: (1) Average values determined from the prism tests. (2) 125 % of the mir.imum value determined from the prism tests. (3) 10G3 psi. The average compressive strength f'm based on 9 p(13 m tests is 1942 psi.125
% of the minimum value determined from the prism tesis is 1875 psi. Therefore the value of f'm to be used in the criteria shall be 1000 psi.
The method used to estimate the mortar strength is described in CES Report No. 553.01. This is based on either the average value or 125 % of the minimum values of both the block and masonry compressive strengths. For the blocks 125 % of the minimum value is 2825 psi and for the masonry the corresponding value is 1875 psi. From Table 1 of CES Report No. 553.01 the compressive strength of masonry f'm corresponding to a net compressive strength of 2825 psi for the blocks is 1650 psi for Types M or S mortar. Since an f'm of 1875 psi was obtained from the prism tests it is deduced that the mortar strength corresponds to either Type M or S with a minimum strength of 1800 psi. It should be noted that this is an approximate method of obtaining the mortar strength and therefore can only be used as an indicator of the mortar strength. 6 CONCLUSIONS The purpose of Action item 1 was to determine the as-built compressive strength of the masonry walls at the Point Beach Nuclear Power Plant to validate the use of the specla! Inspection allowable stresses used in the criteria. This was achieved by extracting and testing nine prism and six block samples from three , walls of the plant. The walls frc9 which the samples were taken differed from those agreed upon of the meeting of June 9-11. 1981 because of difficulties 3
encountered in the field. No samples were tested from Walls 65,104 and 150, however the stairwell wall of Unit 2 was included as an additional wall. Furthermore, a total of nine prisms and six blocks were tested whereas it was agreed to test only five prism and five block samples. Therefore a greater riumber of tests were performed but the samples came from three ratner than five walls. The allowable compressive stress f'm assumed in the criteria was 1000 psi. The lowest value determ!ned from the prism tests was 1500 psi and the everage value of the nine tests was 1942 psi.125 % of the lowest value is 1875 psi. The type of mortar specified in the criteria was Type N and in the criteria this was limited to a compressive strength cl 750 psi. From the prism and block compressive tests it was deduced that the mortar had a compressive strength corresponding to a Type S mortar with a minimum ASTM specifie*) value of 1800 psi. Thus the values of both the mortar and masonry compressim strength, obtained by testing prism and block samples extracted from the walls at the plant, significantly exceeded those assum;d in tha criteria. in conclusion, it is apparent that the standard of construction was of good quality and therefore tne use of allowable stresses for special inspection is justified. Furthermore the compressive strength f'm of masonry assumed in the criteda has a factor of safety of approximately 1.8 when compared to 125 % of the minimum value determined from the tests. The corresponding factor of safety for the assumed mortar compressive strength is of the order of 2 or greater. 4
TABLE 1:
SUMMARY
OF PRISM AND BLOCK COMPRESSIVE STRENGTHS BLOCK PRISM WALL GROSS NET GROSS NET f'm No (psi) (psi) (psi) (psi) (psi) 68 1510 2730 830 1250 1500 1230 2260 850 1300 1560 950 1620 1945 Stairwell 1740 2760 950 1570 1885 Unit 1 2100 3330 980 1530 1835 960 154G 1850 Stairwell 2350 3650 1000 1720 2065 Unit 2 2200 3740 1220 1960 2350 1230 2070 2485 Average 1855 3078 997 1618 1942 Standard Deviation 435 587 141 270 324 I i i l l l l l l l l t 5
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I eeroer no. eee.,e y APPENDIX A I I I g 9 :. 4 ,s; p,, x, ' f. sif l
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I I ' S01L ' TESTlNG 3 SERVICES aisi i _
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I I t I I I l CONCRETE BLOCK AND PRISM TESTING l POINT BEACH NUCLEAR PLANT STS Job 11297 I I I I I lI I 1 I I I 'I
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