Joints in large buildings: a preliminary report

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Joints in large buildings: a preliminary report

NATIONAL RESEARCH COUNCIL OF CANADA DIVISION OF BUILDING RESEARCH

JOINTS IN LARGE BUILDINGS

A Preliminary Report

by

D. G. Mathewson

Report No. 159 of the

Division of Building Research

Ottawa October 1959

PREFACE

A number of inquiries have come to the Division of Building Researoh regarding the correct spacing and proper design of joints for use in large buildings to obviate

unsightly cracking. It Vias at first thought that this was

a building problem the answers to which would be readily found

in the literature. Initial searches for such recorded

informa-tion soon demonstrated a surprising dearth of useful papers. Inquiry was therefore made to building research organizations in other countries, in the first place by the writer at a meeting with his fellow directors in Australia in 1956, and

later by letter. Although some useful suggestions were

received (as will be seen from this report), for which the Division is grateful, it was clear that there was a gap in the literature of building practice regarding this problem.

Further inquiries suggested that information on the proper use of joints in large bUildings was available but only in the private records of experienced architectural and

engineering offices, little of it having been recorded for

public use. Although the majority of buildings appear to

perform satisfactorily with respect to this problem of cracking,

･ｮｯｵｾｬ cases of trouble from this cause have come to the atten-tion of the Division to suggest that the matter was worthy of further study.

During the summer of 1958, a start was made by

assigning a summer student to make a preliminary study of the literature that was available and to assess the information

received from other building research ｾｴ｡ｴｩｯｮｳＮ It was fully

realized that any such short-term study would be preliminary only; it is for this reason that a special qualifying note appears on the title page of this report.

The author of the report was a student in civil

engineering at McGill University, who spent the summer of 1958 working with the Building Structures Section of the Division. His original draft report has been amended and completed by

Mr. W. R. Schriever, Head of the Building Structures Section,

and Mr. W. G. Plewes, a Research Officer of the Section.

Since the original draft of the report was completed,

a useful book by P.

L.

Critchell, on the subject of joints, has

appeared (Bibliography, Page 12). So complete is the treatment

in this volume that there was some doubt whether this reuort should be issued, but it has been decided to issue it ｩｮｾｴｨｩｳ

form if only in view of the useful infonnation contained in

Table I. The Division hopes to pursue further its study of

this matter when time and staff permtt •

Ottr\W3

October

1959

Robert F. LeGget, Director.

A Preliminary Report by

D. G. Mathewson

I INTRODUCTION

The occurrence of cracks in concrete and masonry construction due to volume changes has long been a problem. It is generally accepted that some crack formation in slabs and exterior walls is unavoidable, except in very low

structures. However, much can be done to reduce or control

cracking. Steel reinforcement can control cracking but

usually not completely. Therefore, the remainder of tIle

move-ment must be provided for, particularly in large buildings, by joints especially introduced for the purpose.

The purpose of this report is to review some of the literature on the subject of tllese joints, their location and

spacing in buildings, ｾｩｴｨ special reference to concrete and

to masonry building construction. Such a review seems

particu-larly appropriate in view of the divergence of opinions and practice (Table I) which appears to exist on this subject.

Inquiries were sent to bUilding research stations

and other research organizations throughout the world. The

replies received served to emphasize further both the impor-tance of the subject and the relative dearth of information on

it. The author wishes to acknowledge the assistance received

from all those who contributed generously from their experience and knowledge on this subject through their replies to

inquiries from the Division. Causes of Cracking in Concrete

The major causes of cracking in concrete structures are:

(1) differential settlement; (2) effects of loading; and

(3)

volume changes due to temperature changes,

shrinkage, and change in moisture content.

This report 1s concerned only with volume changes and change in moisture content.

2

-The actual mechanism by which cracks form may be quite complicated but the basic causes involved are

straight-forward. If a structure were freely supported in space, if all

its parts bad the same rates of volume change due to shrinkage and variations in temperature and moistllre, and if, furthermore, all parts of the structure were exposed to the same atmospheric

conditions, no cracks would result. In an actual building,

however, the volume changes and the resulting dimensional

changes tend to be smaller at the foundation level than higher up because volume clmnges in the foundation are minimized by

the insulating effect of the surrounding soil. The use of

different materials in conjunction with each other also leads to cracking, since different coefficients of expansion and/or shrinkage result in movements of one material relative to another.

Temperature changes

The stresses introduced in concrete by temperature

variations can lead to serious cracking. A reduction in

temperature is more serious than an increase because the stresses induced are tensile and because they combine with

the shrinkage stresses. Consequently, from this standpoint

alone, it is preferable to place concrete in cool weather. Under these conditions, the interval between the temperature of the concrete after curing and drying, and the lowest tempera-ture to which it will be subjected, will be reduced.

The coefficient of expansion of concrete varies with the type of aggregate used, but also to some extent with the 6 cement content, a typical value being of the order of 5 x

10-per OF, i.e. very nearly the same as steel. If an unrestrained

slab or wall 100 ft long be exposed to a temperature variation from summer to winter of 100°F the thermal movement might be

about 0.5 in. Greater movements occur at the exposed surface

of the concrete than in the interior, leading frequently to additional warping effects.

Shrinkage

Shrinkage during the curing and drying of concrete

is unavoidable unless the concrete is submerged in water. The

amount of shrinkage varies with the mix and with atmospheric

conditions. A typical coefficient of shrinkage for a standard

mix of 1:2:4 is about 500 x 10- 6. Thus for a 100-ft long slab,

3

-shrinkage occurs depends on the rate of loss of moisture. This rate is important since a slow loss will allow time for the concrete to gain strength and also to undergo a certain amount of plastic flow. More rapid drying will greatly reduce these beneficial effects. Thus for any particular slab, a more

rapid moisture loss (i.e. drying at higher air temperature and lower atmospheric humidity) will result in an increase in the width and number of shrinkage cracks.

Cracks may also result from differential shrinkage and temperature contraction. Tensile stresses are thus induced in the outer shell of the concrete mass when the surface is shrinking and cooling more rapidly than the interior. This effect is not too critical for thin structures such as slabs and walls but it can be a major consideration in massive concrete work.

Changes in moisture content

Another less important factor contributing to the formation of cracks in concrete is the seasonal variation in moisture content due to (a) changes in relative humidity of the air, and (b) direct contact with water. The volume of concrete changes with moisture content variations. The change in length of a lOO-ft long slab due to changing moisture

content may be of the order of 1/8 in. The movement varies with the cement content and the water/cement ratio.

Steel Reinforcement

Steel reinforcement reduces the effect of volume changes in concrete by restraining movements and, if cracks do occur, numerous small cracks appear rather than a few wide cracks. The National Building Code of Canada

(8)

reoommends the following minimum ratios of temperature and shrinkage reinforce-ment area to concrete area:

(I) for floor slabs where plain bars are used - 0.0025; (2) for roof slabs where plain bars are used - 0.003; (3) for exposed walls 8 in. or more in

thickness - exterior face - 0.004 intericr face - 0.002 Also, not less than two 5/8-in. diameter bars

should be placed around all window or door openings. This provision for minimum reinforcing codes is con-sidered by Rensaa (lO}to be insufficient for crack control.

Joint spacing and reinforcement are inter-related variables and the choice of one should be related to the

other. As yet, 110wever, a reliable relationship between the

two quantities does not appear to have been established. Types of Joints

The three principal types of joints, used in both reinforced and plain concrete structures and masonry structures are simple contraction joints, expansion and contraction

joints and construction joints. The first two types, sometimes

referred to as functional joints, provide for movements. Construction joints on the other hand are not designed to prOVide for any movements but are merely separations between consecutive concreting operations.

Since good joints are usually expensive to build, it is desirable to install one joint to serve a dual purpose

whenever possible. By the very nature of its construction an

expansion joint acts also as a contraction joint, a fact which should be kept in mind when selecting contraction joint

loca-tions. A further saving in the number of joints required may

be effected by arranging to have a contraction joint coincide with a construction joint thus eliminating one joint.

II CONTRACTION JOINTS

Shrinkage and reduction in temperature produce contraction in a concrete section or, if the concrete is not

free to contract, tensile stresses. These stresses can be

relieved or reduced to tolerable limits by contraction joints. Such joints allow the contraction to take place along certain pre-selected lines rather than to produce cracks along

acci-dental lines of least resistance. To some extent contraction

joints can also serve as expansion joints.

Among the several terms used for contraction joints

arc dummy-contraction joints and control joints. There is,

however, some confusion over these terms which are often used

interchangeably. In general, contraction joints seem to be

divided into two groups, the true contraction joint and the dummy-contraction or control joint.

A true contraction joint is fonned by providing a complete break between two adjacent sections of concrete, whereas a dum..my-cont ract Lon or control joint is formed by so weakening a section along a certain line tl1at cracking occurs

5

-along the pre-selected line. The reinforcement

types of joints is partially or completely cut. attention should be paid to the sealing of such a water access is undesirable.

Construction Details

at both these Particular joints where

Figure 1 shows some examples of contraction and

dummy-contraction joints. A dummy-contraction joint which is

easy to form and inexpensive can be made by tacking wooden or rubber strips to the inside of the forms ("d" in Fig. 1). After removal of the forms and the wooden strips, a narrow vertical groove is left in the concrete on the inside and

out-side surfaces. Caulking compound can be used on the exterior

face for sealing purposes.

The combined depth of the inner and outer grooves

should be about 1/3 to

t

of the slab thickness.

Remarks

As can be seen from Table I there is considerable variation in the recommended joint spacing (20 to 200 ft). There are in fact some engineers who do not consider joints

to be necessary at all. The spacing of joints depends to some

extent on the degree of exposure of the structure but also on the restraint provided by its construction (reinforcing steel)

and other parts of the structure. To some degree there is a

choice either of joints at short spacings with normal reinforce-ment or of larger unbroken lengths with increased reinforcereinforce-ment.

Many of the references available seem to favour a 20 to 25 ft spacing between contraction joints in walls and

slabs. If a wall is less than 10 ft high, however, and

restrained at the foundation by anchorage to more massive concrete or a rock foundation, it may even crack near the

centre of a 20 ft section. Under such conditions Tuthill (12)

recommends joints at 10 ft intervals. For walls of 10 to 20 ft

in height he suggested that joint spacing should be approxi-mately equal to the wall height.

Walls with frequent openings should have smaller

joint spacings than solid walls. Cracks usually form at

windows and doors where the concrete sections are weakest. Additional reinforcing should therefore be placed at the corners of these openings.

6

-III EXPANSION JOINTS

Expansion joints serve to eliminate or to reduce compressive stresses which develop in concrete, concrete masonry, and brick masonry as a result of thermal expansion

and/or expansion due to increased moisture content. If

neglected, these stresses might conceivably ｣ｬｾｳｨ or crack

some elements of the structure although opinions differ on the need for expansion joints (see below).

In reinforced concrete construction, reinforcement should either be discontinuous across the joint or, if

reinforcement is continuous, tIle bond between the concrete and the steel should be broken on one side of the joint.

Construction Details

These joints are usually made

i

in. to 1 in. wide

and are filled with a compressible elastic, non-extruding material vnlich is intended to accommodate the movements occurring and at the same time provide an adequate seal

against water and foreign matter. Many engineers admit that

no single material has been found yet vnlich will completely satisfy both conditions mentioned. Essentially three types of

jointing materials are used: joint fillers (such as strips

of asphalt-impregnated fibreboard), sealers and waterstops. Sealers (sealing compounds) and waterstops (rubber, plastic or metal) are used where a joint has to be sealed against the

passage or pressure of water. In Fig. 2 examples are shown of

various types of expansion joints.

With regard to the arrangement of expansion joints,

three buildings ｣ｯｮｳｴｲｾ｣ｴ･､ within the last few years in Ottawa

could be sited as examples (Figs.

4, 5

and 6). The plans

illustrate how the different sections of a building are

separa-l;ed into natural units by means of expansion joints.

In the Radio and Electrical Engineering Building of the

National Research Council in Otrbawa , for example, the main

laboratory building was broken up into three sections, each

about 140 ft in ｬ･ｮ｢ｾｨＮ All wings were separated from the

main laboratory wing by expansion joints, thus allowing each

section to move independently. In this building, which is a

reinforced-concrete frame structtlTe, expansion joints were formed by two independent sets of beams and columns separated

by a 1 in. space. This separation \"las made to pass completely

through the building, from the roof to the top of the

founda-tion. Although the functioning of the expansion joint system

seeiTIS to have been satisfactory in this building, and no serious cra cks have formed in the plaster, this example is not suggested as a general rule to follow.

'7

-Remarks

There is a great divergence of 0plnlon concerning the importance of expansion joints in concrete construction.

Some experts recommend joint spacings as low as 30 ft while

others consider expansion joints entirely unnecessary. Joint

spacings of roughly 100 to 200 ft for concrete and roughly 50

to 100 ft for clay brick masonry seem to be typical ranges

recommended by various authorities.

Concrete construction: Those who advocate the compl ete

omission of' eXIX,U1siol1 joints in concrete construction (10, 11)

state that the initial sllrinkage is greater than the expansion

caused by a 100°F increase in temperature. They maintain

therefore that any temperGture increase will tend to close up shrinkage cracks and there wi.Ll, be practically no comp'res s.Lve

stress in the concrete due to thermal expansion. Mr. David Isaacs,

Director of the ｇｯｭｭｯｮｾ･｡ｬｴｨ Experimental Building Station in

Australia, states that all movements in reinforced ｣ｯｮ｣ｲ･ｾ･

may be accommodated by contraction joints and that e::cpanslon

joi.nt s are not nece ssery , He sugGests an 80 ft s pac a.ng for the contraction joints.

Concrete masonry construction: It is well known that

concrete blocks su1'fer from shrinkage and temperature effects.

However there are many views on the use of expansion joints.

Chaney (1) considers that expansion joints should be provided

at 100 ft intervals. In Australia, according to Mr. Isaacs,

bond beams are often used for concrete masonry construction to

avoid expansion joints. The bond beams distribute vertical

loads at each story height and act as a stabilizing beam against

horizontal loading. Both the bond beams and the concrete

masonry are provided with contraction joints, the spacings

being approximately 50 ft and 17 ft respectively. Other

designers consider expansion joints and contraction joints as being of equal importance.

Clay-brick masonry construction: Expansive movement in

clay bricbvork is caused mainly by gain in moisture content

over a period of years after the bricks leave the kiln. It

should be noted that, whereas clay brick expands due to a gain in moisture after leaving the kiln, concrete and concrete

block lose moisture and consequently shrink in volume when

exposed to the atmosphere. Clay bricks start to expand as

soon as they are removed from the kiln, the rate of expansion

decreasing with time. Clay bricks which go directly from the

kiln into walls will therefore n3ve a much larger expansion

than similar bricks VITlich have aged for a few months. Thus the

amount; of expansion to be provided for, i.e. vvidth and spacing of expansion joints, depends on the time that has elapsed since the bricks were removed from the kiln.

8

-According to the Commonwealth Experimental Building Station in Australia, the largest expansion would occur if stiff plastic bricks were used directly from the kiln.

Mr. Isaacs states that bric10vork with cement mortar may expand

as much as ｬｾ to 3 in. in 100 ft. Mr. H. F. ｐｬｵｮｾ･ｲＬ an

American authority on masonry construction, considers that the pertinent clauses of a specification for concrete construction (1940 Report of the Joint Committee on Standard Specifications for Concrete and Reinforced Concrete) are equally applicable to brick construction.

IV JOINT SPACING

Some further notes on factors affecting joint spacing may be helpful.

(1) In reinforced concrete the amount of reinforcement prOVided should be considered when determining the allowable joint

spacing. Sufficient steel must be included to control

cracking between the joints. If the joint spacing is

increased, the reinforcement must be increased corres-pondingly to control cracking over the longer distance. (2) In clay-brick construction both the age of the brick and

the type of mortar used are important factors. Lime

mortars can more readily compress illlder expansive movements than strong cement mortars.

(3) The shape of a building has considerable effect on the

joint locations. If, for example, a building is in the

fonn of a liT" it would be reasonable to provide expansion

joints at the junction of the leg Viith tl:.e main. body of '

the building. If the length of the leg is greater than

80 to 100 ft, a second joint may be necessary.

(4) The type of construction and the climate are also important

in determining the expansion-joint spacing. POI" example,

a building which has uninsulated wa Ll.s or is unheated, must have expansion joints at more frequent intervals than

a heated building. Thelwal movements are reduced vmen an

insulation layer is placed on the exterior face of the structure.

The constrnction of concrete wharves sorves as an

interesting example. In winter the water Lemperatur-e is

about 30°:B' and in summer about 60°F. In the submerged

portion of the wharf, therefore, there will be an armuaL

- 9

may have a 150°F variation. Thus, in order to allow the surface slab to move more freely, joints are required at frequent intervals, possibly every 40 to 50 ft.

(5)

Expansion joints should completely separate the sections of a building so that each section can function as an independent unit. This may be costly and ｣ｯｾｰｬｩ｣｡ｴ･､Ｌ as it may involve the construction of two independent sets of columns and beams at the joints, separated by a 1 in. space. Such costs should, however, be considered against the risk and cost of extensive trouble, which might occur year after year if the joints were omitted.

(6) Thermal expansion of concrete roofs under solar radiation is a common cause of damage to buildings. Murdock

(7)

suggests the following precautions to prevent damage: (a) Allow the roof slab to slide on the supporting

walls with suitable breaking of the plaster finish at the junctions;

(b) Incorporate suitably-designed expansion joints at convenient intervals;

(c) In conjunction with (1) and (2), use a roof covering having a high thennal insulation and whiten the roof in order to reduce temperature movements.

An

example of this phenomenon can be found in several places where cracks have formed in the corners of the plaster walls on the second floor of tIle Building Research Centre in Ottawa. A definite correlation has been found between the width of one of the larger cracks and the temperature of the ' outside air. There are indications that the roof structure is responsible and that the cracks could have been avoided by taking the precautions recommended by Murdock

(7).

V CONSTRUCTION JOINTS

A construction joint is the junction produced by

placing fresh concrete against the surface of hardened concrete; no movement is to be accommodated and the reinforcement is

continuous across this type of joint.

The main problem in the formation of a good construc-tion joint is that of securing bond between the old and new concrete. Par a sound joint, the reinforcing should be cleaned

10

-and the aggregate of the hardened concrete should be exposed by brushing or sand-blasting before placing the new conc:rete. Construction Details

The simplest type of construction joint is a straight

type ｦｯｾ･､ by the usual stop-end board with side supports

nailed to the forms (Fig.

3).

This joint is suitable for thin

slabs and walls. It is not recommended for slabs thicker than

6 in. and should not be used. where a floor finish will not be

provided. In such a case, it might be preferable to have

construct Lon joints coinciding with contraction joints. Another more satisfactory type of joint resembles

tongue-and-groove lumber construction. Vllien preparing to ｦｯｾｮ

the joint, the ordinary type of stop-end board is used w.ith a

timber fixed on the face of the board to provide the groove in

the first part of the slab. The second pl.scinC of concrete

later enters the groo76 to form the tonGue and thus allan far shear forces to he trans!lllttec} throngh ＭｾｬＱ･ joint.

In providinG construction joints it is essential to

mlnlffilze the leakage of grout from under stop-end boards. If

grout does escape, forming a thin wedge, it should be removed before subsequent concreting commences to avoid weakening the

structure. For water-tightness a continuous water-st op of

metal or rubber is essential. For deep slabs grenter than

18 in., in the case of basements vUlere considerable water pressure will be exerted on the joint, a double segmental

joint is considered most effective by Hunter (4). Remarks

Construction joints in beams and slabs should be

formed at the points of minimum shear. Thus for beams the

joint should be at the centre of the span or within the

middle third. Colmnns should be filled to a level preferably

a few inches be Low the junction of a beam or haunch before making a construction joint.

11

-REFERENCES

1. Chaney, D. L. Block Can't be Blamed for All Cracks.

Concrete, v. 59, December 1951.

2. Crane, T. Architectural Construction. Wiley, p.92, 1956.

3. Dunham, C. W. Planning Industrial Structures.

McGraw-Hill, p.165, 1948.

4. Hunter, L. E. Construction and Expansion Joints for

Concrete. Civil Engineering, v. 48, p.157, 1953.

5. Marchant, C. G. and D. S. Wild. Control Joints.

. Progressive Architecture, v. 39, p.146-148, June 1958.

6. Merrill, W. S. Prevention and Control of Cracking in

Reinforced Concrete Buildings. Engineering

News-Record, v. 131, p.893, 1943.

7. Murdock, L. J.

E. Arnold, Concrete Materials and Practice. London,p.157, 1955.

8. National Building Code of Canada (1953). Section 4.6:

Reinforced Concrete. Associate. Committe e on the

National Building Code, National Research Council,

ottawa.

9. Plummer, H. C. Brick and Tile Engineering; Handbook of

Design. Washington, Structural Clay Products

Institute, 1950.

10. Rensaa, E. M.

Buildings. 1953.

The Cracking Problem in Reinforced Concrete

The Engineering Journal, v. 36, p.1429,

11. Tippy, K. C. Good Practice in Concrete Masonry Wall

Construction. American Concrete Institute Journal,

v , 38, 1942.

12. Tuthill, L. H. American Concrete Institute Journal,

12

-BIBI,IOGRAPHY

Concrete MaSOnTJT Foundation Walls. National Concrete

Masonry Association, Chicago, 88p., 1958.

Critchell, P. L. Joints and Cracks in Concrete.

Contractors Record Ltd., London, 232p, 1958.

Fitzmaurice, R. Principles of Modern Building, vol. I,

p.70-76, London, 1938.

Hool, G. A. and W. S. Yinne. Reinforced Concrete and

ｍ｡ｳｯｮｾｊ Structures. McGraw-Hill, 1944.

Judd, S. Bureau of Reclamation Practice in Design of

Joints for Concrete Buildings. American Concrete

Institute Journal, vol. 39, 1943.

Large, G. E. Basic Reinforced Concrete Design.

Ronald Press, 1957.

Reynolds, C. E. Reinforced Concrete Designer's Handbook.

Concrete Publications, 343p., 1957.

Urquhart, L. C., C. E. O'Rourke, and G. Winter. Design

of Concrete Structures. McGraw-Hill, 1958.

Van Breemen, W. and E. A. Finney. Design and Construction

of Joints in Concrete Pavements. American Concrete

Institute Journal, vol. 21, June 1950.

Young, A. M. Crack Control in Concrete Walls. Engineering

TABI,E I

RECOMMENDED JOINT SPACINGS

CONCRETE CONSTRUCTION

Source Type of Construction Joint Type

Expansion Contraction 20 20 20 20 20 20 25 80 \11; } 20-25 25 200 (colder climates) In) 80 60 120 80 Not required

Buildings of srchitectural concrete seldom need expansion joints unless over 200 ft long

Reinforced concrete

Plain concrete slabs up to 9 in. thiCK (a) placed in summer

(b) placed in winter

Reinrorced concrete slabs up to 9 in.

thick

(a) placed in summer (b) placed in winter

Reinforced concrete wall. 8 in. thick L. H. Tuthill (12)

W. S. Merrill (6)

T. Crane (2)

portland Cement Association

Exposed concrete wall Reinforced concrete walls

(a) with frequent openings

(b) withoutfrequent openings

Commonwealth Experimental Building Reinrorced ooncrete Station, N. S. W., Australia

Joints in Concrete construct I on Published by Expandite Ltd., London, N.W.lO, England

E. M. Rensaa (10) Reinrorced concrete

Short spacings or spacings of about 200 ft With added

reinforcement

Cement and Concrete Association, Concrete

London, England

L. E. Hunter (4) Reinforced concrete

Three- and four-story buil dangs ,

Norwegian Building Researoh reinforced concrete floors and

Institute load-bearing ftBlls of lightweight

concrete or brick masonry

Approx. 100 ft, 140 ft max.

80

Approx. 80 Approx. 80

L. J. Murdock (7) Reinforced concrete 100

Dept. of Scientific and Industrial

Research, Building Research Buildings with nat concrete

Station, Gerston, Watford, roofs

Herta, England

C. II. Dunham (3) Variable

100

100-200 Faber, Oscar. Reinroroed Shell concrete

Concrete. London, 1952 Approx. 100

Report of Joint Committee on Standard Specifications for Conorete and Retnroroed Concrete (1940)

Concrete wall

Concrete slab roof

Reinforced concrete retaining wall

200

(under moat severe conditions)

100

100 30

National Building Code. of Canada (Section 4.5.7.1)

Reinforced concrete structures

exceeding 200 I t in langth and of

width less than one-half the length 200 max.

MASONRY CONSTRUCTION Commonwealth Rxperimantal Building Concrete masonry using bond beams

Station, N.::>.W., Australia 17

Concrete bond beams ₅₀

(3 of17 ft)

D. L. Chaney (1)

K. C. Tippy (11) Concrete masonry walls

C. G. Marchant and D. S. Wild (5) Exterior masonry load-bearing ... lls Masonry foundation walls

(a) more than 12 in. exposed

above grade

(b) 12 in., or less, exposed above grade Concrete block Not required 100 Approx. 25 30 Approx. 20 75 max.

National Concrete Masonry

Association concrete masonry foundation walla (a) plain

(b) reinforced

Not recommended unless required by, or aligned With, expansion joints in superstructure (avoid all joints Wherever possible by providing bond beam at top of wall) •

Not required in walls under 150-200 ft in length

35-40ft in walls of over 100 ft in length

Same as (a)

Dept. of Scientific and Industrial Research, Building Research

Station, Garaton, Watford,

Herts., England

Exterior brick caVity walls 40-50

Commonwealth Experimental Building Station, N.S.W•• Australia

Commonwealth of Australia C.S.I. R.O.

Harry C. Plummer (9)

stone masonry

Brickwork in cement mortar

Brickwork

Masonry oonstruotion

100 1}--3in.!lOO

25-50

Report of Joint Committee Recommendation (1940)

PAINTED WIT H

OIL , ASPHALT / TOOLED JOINT

OR PARAFFIN

L

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a)

JOINT

WITH

TRAPEZOIDAL

b) JOINT \f'JITH

SEGMENTAL

KEY IN WALL

KEY IN

'/JALL

JOINT

c)

DUMMY JOINT IN BASEMENT

SLAB

d) DUMMY

CONTRACTION

JOINT

IN

WALL

FIGURE I

EXTERIOR

WALL

COPPER STRIP EXPANDING FILLER

JOINT

c;.

£:C:PPER STRIP

t:

:':.

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ｾｾ ＮｾｾＬＧ＾Ｚ

ROOF

JOINT

JOINT

IN

SLAB

FIGURE

2

/

CONSTRUCTION

CONSTRUCTION JOINT WATERSTOP

SUBGRADE

a) STRAIGHT JOINTS (IN EXTERIOR WALLS 8 SLABS)

WATERSTOP (METAL OR RUBBER)

b) TONGUE - AND - GROOVE AND SEGMENTAL JOINTS

FIGURE 3

ｾｾＭＭＭＮ

ＱＳＴｾＭ

210'

JOINT - I" EXPANSION JOINT

'o

-e

"'\---,_v

(b) PLAN OF INTERIOR COLUMN AT EXPANSION JOINT 65' 0) PLAN OF BUILDING ,11.-', • '<;J . ' • '...ｾＮ \ CAISSON (BELOW) EXPANSION JOINT

16 OZ. COPPER FLASHING _

m**S ;;::::::::::::::::;:,.;;;]

q' •• ' LAB. WING - NAILING STRIP .ｾ-.. . .'ｾ_'. , ,: ELECT. WING

(e) PLAN OF EXTERIOR COLUMN AT EXPANSION JOINT ＵＯｾ COVER

r

-

5.ＧｴｾＧ SAFETY THRESHOLD ＧＢＮＺＺＺＺＺＺＺＺＺ］ＭＭｾｾｾＡＭｬＷｚｾＭ ." 1;. '.'

LJ

EXPANSION JOINTS 12 GA. LUGS WELDED AT 2'-0" O.C.

(d) EXPANSION JOINT IN PARAP[ T WALL ON ROOF

(e) THRESHOLD COVERING EXPANSION JOINT IN FLOOR

FIGURE 4

ｦｊ＼ａｊｾｅｌｅ｟

(fV\DIO a

OF EXPANSION JOINTS IN A LARGE BUILDING

ELECTRICAL ENGINEERING LABORATORY BUILDINGI

I" EXPANSION JOINT 10 m 52' I N

-+-DETAIL @

_1/;.-4'LONG,16"O.C. (THESE RIIRS IN ADDITION TO NORMAL SIIRS WHICH LAP 32 BAR DIA.)

N

'"

139'

16 OZ COPPER STRIP TO A HEIGHT OF 1'-0" ABOVE GRADE IF THERE IS NO BASEMENT OR OTHER FLOOR LOWER THAN GRADE, OMIT COPPER STRIP.

bl CONSTRUCTION JOINT IN FOUNDATION WAll

01 PLAN OF BUILDING

COPPER EXPANSION STRIP -- BRICK

PRESSURE SEAL (SPONGE RUBBER CORE WITH PLASTIC COAT) -MASTIC FILLER

JL

I "

Ｂｴｾｾ

"".. I" CORK---..wu PLASTER -

-ｉＯｾ +-4'LONG ,IS"O.C.(THESE BARS IN ADDITION TO NORMAL BARS WHICH LAP 32 BAR DIA.)

COMPACTED GRAVEL

c) CONSTRUCTION JOINT IN SLAB ON GROUND d) EXPANSION JOINT AT

®

(SEE FIGURE 0 1

FIGURE 5

EXAMPLE OF ARRANGEMENT OF EXPANSION JOINTS IN A LARGE BUILDING (FOOD AND DRUG LABORATORY,

66' 170'

-

_v

)

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--®

U

n

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49' EXPANSION JOINT WALL .__---+t--16 'IF 40 314'

III EXPANSION JOINT

PLAN OF BUILDING

DETAIL OF COLUMN AT B

FIGURE 6

EXAMPLE OF ARRANGEMENT OF EXPANSION JOINTS IN A LARGE BUILDING

(CHEMISTRY t RADIOACTIVE ORES 8 ADMINISTRATION BUILDING