11th lNTERNATI0NAL BRICKlBLOCK MASONRY CONFERENCE

TONGJl UNIVERSITY, SHANGHAI, CHINA, 14 - 16 OCTOBER 1997

STUDIES OF MECHANICAL PROPERTIES OF SMALL HOLLOW CONCRETE BLOCK MASONRY WITH REINFORCED CORES

Sun Qingping' , Hou Ruxin and' Cui Xianwen'

I. ABSTRACT

Based on tests, this paper systematically studies the mechanical properties of small hollow concrete block masonry with reinforced cores. The data obtained provide reference basis for the design of multi -story residential buildings constructed with small hollow concrete blocks.

2. INTRODUCTION

Structural measures using reinforced cores are taken for small hollow concrete block residential buildings. How do the reinforced cores function? This paper systematically studies the mechanical properties of such masonry, namely, the axial compressive strength and elastic modulus of masonry, the affection factor of masonry in eccentric compression, the stabilization coefficient of reinforced core masonry long columns in axial compression and shear strength of masonry along horizontal mortar joints. And contrast tests were carried out to compare with the mechanical properties of hollow masonry. Through the data analysis of contrast tests, we can cIearly understand the function of reinforced cores in small hollow concrete block buildings.

3.RA W MATERIALS AND THEIR PROPERTIES

KEYWORDS: small hollow concrete block; masonry; masonry with reinforced cores

I Sichuan Institute of Build ing Research

285

properties ofthe raw material: cement Grade: 525#(R), compressive strength: 586kg/cm2 with other properties

up to standards concemed. Sand Unit weight: 1450kg/m3

, specific gravity: 2.69, fineness modulus: Mx=2.37, comforming to the index specified in JGJ52-79.

Gravei Gravei size: 5-20mm, unit weight: 1690kg/m3, specified in JGJ52-79.

Reinforcement Reinforcement $12 and $14 were used. the testing results ofproper­ties are shown in Table I .

Table I Testing Results ofReinforcement Stresses

Yielding strength Tensile strength Elongation Elastic modulus

(N/mm2) (N/mm2

) percentage (%) (N/mm2)

$12 357 456 40.3 -

<p14 270 366 44.7 1.99 x 105

Small hollow concrete blocks (hereinafter called SHCB for short). The strengths of the first and second batch block were 11.8Mpa and 10.6MPa respectively. Both reached class MUIO and the appearance quality met the requirements stipulated in GB8239-87.

4. MASONRY TESTS AND RESULTS

4.1 Masonry dimensions and test method

The masonry dimensions w~re 590 x 590 x 1000mm. Tests were carried out according to the " Test Methods for Basic Mechanical Properties ofMasonry ,. GBJ129-90.

4.2 Test results

The masonry with reinforced cores was laid with masonry mortars of different strengths and miniature vibrators were used for pouring core concrete. The strengths of the reinforced core concrete cubic specimens were defined between 24.5-30Mpa and the cubic specimens were cured under the same conditibns as the masonry specimens. The following are the test results of the mechanical properties of the masonry with reinforced cores.

4.2.1 Axial compressive strength ofthe masonry with reinforced cores

Thirty-five masonry specimens were made with masonry mortars of different strengths. The test results of the axial compressive strength of the masonry are shown in Table 2&3.

4.2.2 The elastic modulus ofthe masonry with reinforced cores in axial compression

As the stress-strain relationship ofthe SHCB masonry in axial compression is non-linear,

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the elastic modulus is not a constant. The stress-axial strain relationship curve was drawn with cr as ordinate and E as abscissa, taking the secant modulus when the stress cr=O.4:fcm(in the curve) as the e1astic modulus of the masonry, ca1culating according to Eq.(l) :

where

E = 0.4fcm

&0.4

E -- elastic modulus (N/mm2) ofthe masonry

EOA - axial strain value corresponding to Oo4lcm

(1)

In order to compare the elastic modulus (masonry with dimensions of 590 x 590 x

600mm) when cr=0043lcm and to ca1culating, the elastic modulus test results of the reinforced core masonry are listed in Table 4.

4.2.3 Affection coefficient of reinforced core masonry in eccentric compression

Tht: relation eccentricity eoly of the eccentrically compressed reinforced core masonry was 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 (y is the distance from the center of gravity of section cdge i!l the direction ofaxial force) . The test results are indicated in Table 5.

Table 2 Axial Compressive Strength ofReinforced Core Masonry

Masonry Quantity of Strength of Strength of Strength of masonry

dimensicns masonry blocks mortars (MPa)

(mm) (n) (MPa) (MPa) Initial crack Failure

595 x 190 x 1000 3 lU! 3.8 10.3 14.53

595 x 190 x 1000 6 11.8 5.3 10.09 15.1

592 x 190 x 1000 4 11.8 7.6 10.56 15.3

595 x 190 x 1000 4 11.8 IJ.l 10.58 16.0

595 x 190 x 1000 3 11.8 15.3 7.4 18.1

595 x 190 x 1000 3 11.8 22.2 14.9 22.5

590 x 190 x 1000 3 11.8 30.6 15 .2 23.9

Note: I. There were hooks of 6.54d long at both ends ofthe reinforcement.

2. The reinforcement was $14.

ratio of Initial

crack Strength to

Failure Strength

0.73

0.73

0.71

0.67

0.42

0.70

0.63

4.204 Stabilization coefficient of reinforced core masonry long colui"lm m axial compression

The compressive strength of SHCB was 1O.6Mpa, the strength of the masonry mortar was 15.1 Mpa, the strength ofreinforced core concrete cubes was 24.5MPa and the core steel was $14, one for each core.

The section size of the masonry specimen was 590 x 190mm, the nominal height of

masonry specimens was 1.0m (5 blocks), 1.6m (8 blocks), 2.2m (11 blocks) and 2.8m (14 blocks). The leveling thickness of mortar at masonry top was about 20mm and the ratio of height to thickness of the specimens was 5.26, 8.58, 11.58 and 14.74

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respective1y. Table gives the test results of stabilization coefficient of reinforced core masonry long column in axial compression.

TabJe 3 Axial Compressive Strength ofReinforced Core Masonry

Masonry Quantity of Strength of Strength of Strength of masonry ratio of Initial

dimensions masonry blocks

(mm) (n) (MPa)

595 x 190 x 1000 3 10.6

595 x 190 x 1000 3 10.6

595 x 190 x 1000 3 10.6

595 x 190 x 1000 3 10.6

*The reinforced core concrete was not dense.

Note: I. The reinforcement was <p12.

mortars

(MPa)

O

8.3

22.3

23.5

2. There were hooks of 6.5d long at both ends.

(MPa) crack Strength to

Initial crack Failure Failure Strength

4.1 7.3 0.56

8.9 14.6 0.45

9.0 18 .9 0.55

13.0 18.8 0.70

3. The strength of reinforced core concrete cubes was 17 .1 Mpa.

Table 4 Elastic Modulus Test Results ofReinforc'ed Core Masonry

Masonry Masonry Strength of Strength of Strength of Value ofa Elastic Modulus

dimensions quantity blocks mortar masonry (I04Mpa)

(mm) (n) (MPa) (MPa) (MPa) cr=O.4fcm I cr=0.431; ..

<p 12 Reinforced Core Masonry

595 x 190 x 1000 3 10.6 O 7.1 5.284 0.96 1.0

595 x 190 x 1000 3 10.6 8.3 16.7 6.010 1.32 ' .42

595 x 190 x 1000 3 10.6 22 .3 18.7 6.895 .> 1.90 2.04

595 x 190 x 1000 2 10.6 23.5 17.5 4.135 2.82 3.10

<p 14 Reinforced Core Masonry

595 x 190 x 1000 3 11.8 3.8 14.3 5.625 1.807 1.940

595 x 190 x 1000 3 11.8 5.7 14.5 5.663 1.963 2.091

592 x 190 x 1000 4 11.8 7.6 15.6 5.956 1.953 2.132

595 x 190 x 1000 .4 11.8 11. 1 15.9 5.546 1.880 2.026

Table 5 Affection Factor ofReinforced Core Masonry in Eccentric Compression

Masonry Masonry Strength of Strength of Strength of ao/a

dimensions (mm) quantity blocks mortar eo/y masonry ao (Code 88)

(n) (Mpa) (MPa) (MPa)

590 x 190 x 1000 3 11.8 11.7 O 18 .85 1.0 1.0

590 x 190 x 1000 3 11.8 11.7 0.2 18.75 0.995 1.12

590 x 190 x 1000 3 11.8 11.7 0.4 13.48 0.715 1.05

590 x 190 x 1000 3 11.8 11.7 0.6 10.63 0.564 1.18

592 x 190 x 1000 3 11.8 11.7 0.8 8.49 0.450 1.32

593 x 190 x 1000 3 11.8 11.7 1.0 6.37 0.336 1.35

4.2.) Shear strength of reinforced core masonry along horizontal mortar joints

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The strength of SHCB was 10.6 MPa, the strength of masonry mortar was 2.51 , 3.14,7.49, 15.55Mpa respectively and the dimensions ofmasonry were 590 x 190 x

600mm. •

Table 6 Stabilization Coefficient ofReinforced Core Masonry Long Column in Axial Compression

Masonry Masonry Strength of Strength of ratio of

dimensions (mm) quantity blocks mortar height to

(n) (Mpa) (MPa) thickness l3 595 x 190 x 1000 3 10.6 15 .1 5.26

595 x 190 x 1000 3 10.6 15 .1 8.58

595 x 190 x 1000 3 10.6 15.1 11.58

595 x 190 x 1000 3 10.6 15.1 14.74

The way of making the masonry: After the masonry was laid, it was cured indoors for 15 days. Three steel bars were put respectively in the 3 cavities at the center, then concrete was poured and tamped with a miniture vibrator. After curing of 28 days, the masonry was turned 90 degrees, making the horizontal mortar joints upright. A force face of 190 x 190mm was troweled in the

middle of the section between the two shear mortar

Strength of $01$ masonry 4>0 (Code 88)

(MPa)

18.1 0.96 0.98

18.3 1.0 I 0.94

16.3 0.90 0.85

15.5 0.86 0.73

joints at the top of the masonry with high strength cement mortar (higher than that of reinforced core

Fig.1 Specimen in double shear

concrete), and one supporting face of 190 x 190mm was troweled by each side of the

shear mortar joint sections at the bottom of the masonry. The force face and the supporting face, with a thickness of 20mm for each should be parallel to shear section mortar joints (see Fig.1)

The shear strength of the masonry along horizontal joints (through joints) is ca1culated in accordance with Eg. (2) :

r Nv J v.m = 2A

where !vm - compressive strength of masonry along horizontal joint section (MPa) Nv - shear failure load (N) A - area of single shear face of masonry (mm2

)

(2)

For the test results of compressive strength of the reinforced core masonry along horizontal joints (through joints), please see Table 7.

5. ANALYSIS OF THE TEST RESULTS

5.1 Axial compressive strength of reinforced core concrete

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The test results (Tables 2&3) ofaxial compressive strength of reinforced core masonry indicated that with the strength ofthe reinforced core concrete remaining unchanged, the strength of the masonry increased with the raising of that of the masonry mortars, though the magnitude was not notable. For example, when the strength of masonry mortar was 3.8Mpa, the strength of the masonry was 14.53Mpa; While the strength of the masonry mortar increased to 30.6Mpa, the strength of the masonry was raised to 23.9Mpa. That is to say, when the strength of the mortar increased by 7 times, the strength of the masonry only increased by 64 per cento This fact show that, it was the reinforced cores that play a leading role in the compressive strength of the reinforced core masonry.

Table 7 Shear Strength ofReinforced Core Masonry Along Horizontal Mortar Jonits

Dimensions of Strength of Strength of Strength of Shear strength Quantity of

masonry (mm) blocks (MPa) mortars (MPa) reinforced core (MPa) Masonry (n)

concrete (MPa)

Steel <1>14

590 x 190 x 600 10.6 2.51 22.25 2.16 3

590 x 190 x 600 10.6 3.41 22.25 2.55 3

590 x 190 x 600 10.6 7.94 22.25 2.87 3

590 x 190 x 600 10.6 10.94 22.25 3.06 3

§90 x 190 x 600 10.6 15.55 22.25 3.04 3

Stee\ <1>12

590 x 190 x 600 3.41 22.25 2.51 3

590 x 190 x 600 10.94 22.25 2.94 3

the masonry mortar, the strength of the reinforced core masonry was significantly increased than that of the hollow masonry as shown in Table8. The data listed in the t?ble indicate that the former was increased by 1.34-1.3 5 times than the latter.

From the point of view theory, the strength of reinforced core masonry should be the superposion of the strength of the hollow masonry and that of concrete cores and the yielding strength of the steel, namely:

N = m[AJm + AJc.u + As/y] (3)

Where N - carrying capacity of reinforced core masonry (N); m - coefficient of working conditions; Am - section area ofhollow masonry (mm2

);

Im - strength ofhollow masonry (N/mm2);

Ac - section area of concrete core (mm2);

leu - strength of core concrete column (=0.67fc) (N/mm2);

As - section area of steel (mm2);

h - yielding strength of steel (N/mm\

The ca1culations based on Eq. (3) are listed in Table 9.

In table 9, the coefficient of working conditions m was approximately 1.0, indicating

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that the m for reinforced core masonry is slightly higher than that for normal (compound) brick masonry, because the closed walls and ribs restrict the concrete core to a certain extent. For the sake ofsafety ofreinforced cote masonry, 0.9 is recommended for m the coefficient of working conditions for the masonry [0.8- 0.9 for (compound) brick masonry].

Table 8 Comparison of Compressive Strength Between Hollow Masonry and Reinforced Core Masonry

Dimensions of Strength Strength of Cubic strength of Strength of ratio of Strength core

masonry (mm) ofblocks mortars core concrete hollow masonry masonry to Strength of

(MPa) (MPa) cubes (MPa) (MPa) hollow masonry

595 x 190 x 615 11.8 12.7 - 7.6 -

595 x 190 x 1000 11.8 11.5 - 8.5 -

592 x 190 x 610 11.8 12.7 24.5 17.8 2.34

593 x 190 x 1000 11 .8 13.4 24 .5 20.0 2.35

The characteristics of failure of reinforced core masonry in axial compressive were generally the cracks appeared from the top, then developed to the vertical mortar joints, and the junctions of the core concrete and walls or ribs. Prior to failure, cracks often occurred at the joints along the first or second block at the bottom of the masonry. The ratio of initial crack strength to fllilure strength was between the range of 0.4- 0.8.

Table 9 Calculation Based on Eq.(3)

Hollow masonry Reinforced core masonry

No Strength of Am Im Strength of Ac leu A.,' f; ' m

mortars (mm2) (N/mm2

) masonry (mm2) (N/mm2

) (mm2) (mm2

)

(N/mm2) (N/mm2

)

I 3.9 112100 5.85 3.9 49052 20.97 154 270 0.94

2 5.0 112100 7.05 5.3 49052 20.97 154 270 0.90

3 11.8 112100 8.20 11.8 49052 20.97 154 270 0.96

4 15 .1 112100 8.80 15.3 49052 16.42 154 270 1.10

5 23 .1 112100 13.30 222 49052 16.42 154 270 1.03

6 30.0 112100 13.80 30.6 49052 16.42 154 270 1.12

Average 1.0

From the variation of stresses of the masonry core steel bars measured, one can see that it is a relationship of compression-strain as shown in Fig.2&3. From the strength of masonry mortar Mo, Ms, M7.s, M IS , to M20, the strain situation of steel was consistent when the masonry was in axial compression.

5.2 Elastic modulus ofthe reinforced core masonry

From the analysis of the measured elastic modulus data of the reinforced core masonry in axial compression, it is found that the values of the elastic modulus tend to rise with the increase of the strength of the masonry mortars, though not very evident.

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However, on the condition that the strengths ofboth masonry and mortars were basically same, the elastic modulus of the reinforced core masonry was several times higher than that of the hollow masonry. Take the data in Table 10. The elastic moduli of the reinforced core masonry were raised by 1.65-3.36 ' times than that of the hollow masonry .

. / /' V

IJ .7'

Fig. 2 Load-steel strain relationship of

masonry M5

Fig. 3 Load-steel strain relationship of

masonry M20

Table 10 Comparison ofElastic Modali (a=OA3!cm) Between Reinforced Core Masonry and Hollow Masonry

Strength of masonry Strength of mortars Moduli ofhollow Moduli of

(MPa) (MPa) ,masonry E Reinforced core E' (x 104Mpa) (x 104MPa)

11.8 12.9 0.640 2.062

11.8 11.45 0.590 2.062

9.8 9.1 0.325 1.420

12 11.6 0.762 2.062

9.3 10.3 0.613 2.062

E'/E

3.16

3.43

4.36

2.65

3.36

5.3 Affection coefficient o.fthe reinforced core masonry in eccentric compression

For axial specimen and specimen with eccentricity eoly=0.2, the failure was characterized by compressive damage at the whole section; as for masonry with eoly=OA, when load was significant, horizontal cracks appeared first, then the compressive region failed; while for masonry with eoly~0.6, with the increase of loading, the horizontal cracks reached or overpassed the central axis of the section, the compressive region remllrkably became smaller and the bearing capacities notably decreased. Such case was similar to the failure features of non-reinforced brick masonry in eccentric compression, but quiet different from the features of reinforced concrete member subject to eccentric compression.

The test values of affection coefficient of the reinforced core masonry in eccentric compression were higher than the calculated values based on the formula a=1I[1+12(eola)2] but for the sake of safety, the affection values of reinforced core

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masonry in eccentric compression are adopted in accordance with the "Design of Masonry Structure" OB13-88.

When the reinforced core masonry was in eccentric compression, the testing results of steel stresses indicated that the compressive stresses of steel dose to or reached yielding strength when the specimen with relative eccentricity eoly=O-O.4 was subject to limit load; in case of normal force (N/NP-;:,O.4) , the stresses of steel were only 30-40Mpa. With regard to the masonry with relative eccentricity eoly=0.6, the steel remained in a state of compression, but the steel stresses greatly decreased than the former when the specimen was under limit load or normal load. And as for the masonry with relative eccentricity eoly=0.8, the strains of steel under step-by-step loading were scattered owing to big test errors. However, the tests reflected the phenomenon that both of the tensi:e and compressive stresses were small under normal loading. When the masonry with rei ative eccentricity eoly=I.O was subject to great loading, the steel was in tension (horizontal cracks overpassed section axial center), the compressive area of the section was greatly reduced and the limit bearing capacity was remarkably decreased. Looking from the outer surface of the masonry, the horizontal mortar joint cracks run nearly through the whole section. The limit tensile strain of the steel was about (8-12) x 10-4, and it became very small under normalload, not exceeding 3 x 10-4 (60Mpa).

Figures 4, 5&6 show the load-steel strain relationship of several kinds of masonry in eccentric compression.

Fig. 4 Load-steel strain relationship of masonry Fig. 5

in eccentric compression (e,/y=O.4)

Load-steel strain relationship of masonry

in eccentric compression (e,/y=O.6)

5.4 Stability of the reinforced core :nasonry in axial compression

Under axial compression, the features of occurring crashes of reinforced core masonry long columns were similar to that of short ones in many aspects. The initial cracks appeared at longitudinal mortar joints first, then extended to the blocks with the increase of loading. When loading was dose to ultimate, two cracks appeared on the wider side of the masonry and the specimen would lose stability and collapse with continuous loading. The test values of stability coefficient of the reinforced masonry long colurnn ~o were

293

higher than that of brick columns and plain concrete columns, while between that of combination columns (p=OA%) and reinforced concrete columns. The current state standard "Design Code of Masonry Structures" GBJ3"88 stipulates that regarding

the value of SHCB masonry 4>0, it is necessary to multiply the ratio of height to thickness 13 by the factor of 1.1, then to consult the table conceming the values of brick masonry 4>

or to calculate according.

The test data of SHCB masonry long columns indicated the value of 13 may be taken without multiplying the factor 1.1. For walls with core spacing not exceeding 600mm (cavity filling rate>O.25), it is not necessary to multiply the factor of 1.1 when calculating the wall bearing capacity 13 in consideration of the strengthening effect of the cores.

When the reinforced core masonry long columns were subject to axial compression, the measured results of stresses changes of steel indicated that for long columns with height of 1 ~2.2m (13=5.2~ 11.53), the steel

:::~~;;:~ Np=6~7Kr{

''''' Jfl4 stresses reached or neared yield strength ~. - -7.,--

as the load reached or neared ultimate -/J -8 ~.. -0·_·--"; 6 I" ,. strength; Under normal 10ad (NINP""OA), Fig.6 Load-steel strain relationship of the stresses of the steel were very small, oot exceeding 80Mpa, only 38% of the yie1d strength of the steel. With regard to

masonry in eccentric compression

(eofy=I .0)

specimen of 2.8m high (13=14.74) subject to limit load, the steel stresses were approximately 120Mpa, far from the yield strength of the steel. In case of normal loads, the stresses of stee1 were round 40Mpa only. Therefore, in calculating the static bearing capacities of SHCB reinforced core masonry long columns (Ho>2.8m), it is necessary to multiply a factor less than 1 to get the stresses of steel. Owing to limited specimens, the data were inadequate. It is hard to give a definite value.

Figures 7&8 show the load-steel strain relationship oftwo long reinforced core masonry columns.

5.5 Shear strength ofthe reinforced core masonry

The testing data of shearstrength of the reinforced core masonry showed that on the condition of equal strength of core concrete, the shear strength of the masonry was heightened with the increase of the masonry mortars. For mortar strength between 2.51 ~lO .94MPa, the shear strength ofmasonry was raised and the raising tended to slow for high strength mortars.

Compared with the shear of hollow masonry with same conditions, the strength of the

294

rei. forced core masoruy was greatly increased as shown in Table 10.

The data in Table 10 indicated that when the strength of masonry mortars was between 2.51 - 15.55Mpa, the shear strength of the reinforced core masonry was increased by 19.64- 11 .26 times than that of hollow masonry and by 10.8- 6.20 times than that of brick masoruy.

Table 11 Compression of Shear Strength Between Reinforced Core Masonry and Hollow Ones

Strength of mortars (MPa) 2.15

Reinforced core masonry f.m (MPa) 2.16

Hollow masonry J,~ (MPa) 0.11

Brick masonry J,% (MPa) 0.20

f,.l f~m 19.64

f,.l f~~ 10.30

18 ..

"*<0 .

/ '/­,y/

,; / '

16~: //(.( 'f~"''''' 3';111-

:"01

• ti -:l. -.., - 8 -, o -o ..

Fig. 7 Load-steel suain relationship of long

columns (1.6m)

6. CONCLUSIONS

3.14 7.94 10.94 15.55

2.55 2.89 3.06 3.04

0.13 0.19 0.23 0.27

0.23 0.35 0.41 0.49

19.62 15.21 13 .30 11 .26

11.09 8.26 7.46 6.20

Fig. 8 Load-steel strain relationship of long

colurnns (2.2m)

(1) On the condition that the strength of core concrete was consta.l1t and the strength of the masonry mortars was within the range of 3.8- 30.6Mpa, the axial compressive strength of SHCB reinforced core masonry was heightened with the increase of the strength of the masonry mortars. And with equal strength of both blocks and mortars, the compressive strength of the reinforced core masonry was raised by 1.5- 2.0 times than that of hollow masonry. The calculation of the bearing capacities of the reinforced core masonry and the concrete core and the yield strength of the steel, confirming to the theoretical calculating equation N=(A"fm+Acfcu+AJ'y) . When the coefficient of working conditions m was equal to about 1, the bearing capacities were slightly higher than that ofnormal composite brick masonry. For the sake of safety, 0.9 was recommended for m.

(2) On the condition that the strength of the core concrete remained constant, the elastic modulus of the reinforced core masonry in axial compression was raised with the

295

increase of the strength of the masonry mortars though not very notably. In case of equivalent strength of blocks and mortars, the elastic modulus of the reinforceó core masonry was heightened by 1.36- 2.76 times than· that ofthe hollow ones. .

(3) When the relative eccentricity eofy=0.2, 004, 0.6, 0.8 and 1.0, the test values a ' ofthe affection coefficient of the reinforced core masonry in eccentric compression were ali higher than the calculated value as per equation a=I/[1+12(eo/a)2] . F0f the sake of safety, the values of the affection coefficient of the reinforced core masonry in eccentric ::orr.prt:ssion are computed in accordance with the values a provided in "Design Code ofMasonry Structures" GBJ3-88 in the design ofSHCB buildings.

(4) The test data of stability coefficient <1>0 of the reinforced core masonry long columns were slightly higher than or close to the stability coefficient of brick columns and plain concrete columns, while between that of composite brick columns (p=O.4%) and reinforced concrete columns. For the sake of safety, the values of stability coefficient <I> of reinforced core masonry long rolumns are computed according to the values <I> provided ir, the "Design Code of Masonry Structures" GBJ3-88 in designing

SHCB building.

(5) The shear strength at section along the horizontal mortar joints ofthe reinforced core masonry increased with the raising of strength of masonry mortar provided that the strengths of core concrete remain unchanged. In case the strength of blocks was same as that of mortars, the shear strength of the reinforced core masonry was heightened by 10- 19 times than the hollow masonry, which may benefit to earthquake resistance of SHCB buildings.

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