Structural Masonry Designers' Manual

by Curtin, W. G.; Shaw, Gerry; Beck, J. K.; Bray, W. A.; Easterbrook, David

• ISBN13: 9780632056125
• ISBN10: 0632056126
• Edition: 3rd
• Format: Hardcover
• Copyright: 2006-07-12
• Publisher: Wiley-Blackwell

Summary

This major handbook covers the structural use of brick and blockwork. A major feature is a series of step-by-step design examples of typical elements and buildings. The book has been revised to include updates to the code of practice BS 5628:2000-2 and the 2004 version of Part A of the Building Regulations. New information on sustainability issues, innovation in masonry, health and safety issues and technical developments has been added.

Author Biography

Curtins Consulting Engineers is a medium sized firm of structural engineers with 11 offices in the UK. They are well known for their work on foundations and have also authored another book with Blackwell Structural Masonry Designers’ Manual (third edition due 2005).

Dave Easterbrook - Lecturer, School of Engineering, University of Plymouth.

Table of Contents

Preface to the Third Edition	x
Acknowledgements	xi
The Authors	xii
Notation	xiii
Introduction	1	(3)
Present structural forms	1	(1)
Examples of structural layout suiting masonry	2	(1)
Reinforced and post-tensioned masonry	2	(1)
Arches and vaults	2	(1)
The robustness of masonry structures	2	(1)
Prefabrication	3	(1)
Future tradesmen	3	(1)
Engineering education	3	(1)
Advantages and disadvantages of structural masonry	4	(6)
Advantages	4	(3)
Cost	4	(1)
Speed of erection	4	(1)
Aesthetics	4	(1)
Durability	5	(1)
Sound insulation	5	(1)
Thermal insulation	5	(1)
Fire resistance and accidental damage	5	(1)
Capital and current energy requirements	6	(1)
Resistance to movement	6	(1)
Repair and maintenance	6	(1)
Ease of combination with other materials	7	(1)
Availability of materials and labour	7	(1)
Recyclability	7	(1)
Disadvantages	7	(3)
Lack of education in masonry	7	(1)
Increase in obstructed area over steel and reinforced concrete	7	(1)
Problems with some isolated details	7	(1)
Foundations	8	(1)
Large openings	8	(1)
Beams and slabs	8	(1)
Control joints	8	(1)
Health and safety considerations	8	(2)
Design philosophy	10	(6)
Strength of material	10	(1)
Exploitation of cross-section	10	(3)
Exploitation of essential building elements	13	(3)
Limit state design	16	(2)
Basis of design (1): Vertical loading	18	(29)
Compressive strength of masonry	18	(1)
Characteristic strength and characteristic load	18	(2)
Partial safety factors for loads, γf	20	(1)
Characteristic compressive strength of masonry, fk	20	(7)
Brickwork	22	(1)
Blockwork	23	(2)
Natural stone masonry and random rubble masonry	25	(1)
Alternative construction techniques	26	(1)
Partial safety factors for material strength, γm	27	(1)
Manufacturing control (BS 5628, clause 27.2.1)	27	(1)
Construction control	27	(1)
Slenderness ratio	28	(1)
Horizontal and vertical lateral supports	28	(4)
Methods of compliance: Walls -- horizontal lateral supports	29	(3)
Methods of compliance: Walls -- vertical lateral supports	32	(1)
Effective height or length: Walls	32	(2)
Effective thickness of walls	34	(1)
Solid walls	34	(1)
Cavity walls	34	(1)
Loadbearing capacity reduction factor, β	35	(1)
Design compressive strength of a wall	36	(1)
Columns	36	(3)
Slenderness ratio: Columns	36	(1)
Columns formed by openings	37	(1)
Design strength	38	(1)
Columns or walls of small plan area	39	(1)
Eccentric loading	39	(1)
Combined effect of slenderness and eccentricity of load	40	(3)
Walls	40	(1)
Columns	41	(2)
Concentrated loads	43	(4)
Basis of design (2): Lateral loading -- tensile and shear strength	47	(26)
Direct tensile stress	48	(1)
Characteristic flexural strength (tensile) of masonry, fkx	48	(3)
Orthogonal ratio	49	(2)
Moments of resistance: General	51	(3)
Moments of resistance: uncracked sections	51	(2)
Moments of resistance: Cracked sections	53	(1)
Cavity Walls	54	(3)
Vertical twist ties	55	(1)
Double-triangle and wire butterfly ties	56	(1)
Selection of ties	56	(1)
Double-lead (collar-jointed) walls	57	(1)
Grouted cavity walls	57	(1)
Differing orthogonal ratios	57	(1)
Effective eccentricity method of design	57	(1)
Arch method of design	58	(4)
Vertical arching	58	(2)
Vertical arching: Return walls	60	(1)
Horizontal arching	60	(2)
Free-standing walls	62	(1)
General	62	(1)
Design bending moments	62	(1)
Design moment of resistance	63	(1)
Retaining walls	63	(1)
Panel walls	63	(6)
Limiting dimensions	63	(1)
Design methods	64	(1)
Design bending moment	64	(4)
Design moments of resistance	68	(1)
Design of ties	68	(1)
Propped cantilever wall design	69	(1)
Geometric and other sections in shear	70	(1)
Eccentricity of loading in plane of wall	70	(1)
Design of walls loaded eccentrically in the plane of the wall	71	(1)
Walls subjected to shear forces	71	(2)
Characteristic and design shear strength	71	(1)
Resistance to shear	72	(1)
Strapping, propping and tying of loadbearing masonry	73	(21)
Structural action	74	(2)
Horizontal movement	76	(1)
Shear keying between wall and floors	77	(1)
Holding down roofs subject to upward forces	77	(1)
Areas of concern	77	(1)
Other factors influencing the details of connections	78	(2)
Illustrated examples of strapping and tying	80	(9)
Design examples: Straps and ties for a three-storey masonry building	89	(5)
Stability, accidental damage and progressive collapse	94	(16)
Progressive collapse	94	(2)
Stability	96	(2)
Accidental forces (BS 5628, clause 20)	98	(1)
During construction	99	(1)
Extent of damage	99	(1)
Design for accidental damage	100	(10)
Partial safety factors	100	(1)
Methods (options) of checking	101	(1)
Loadbearing elements	101	(2)
Protected member	103	(6)
General notes	109	(1)
Structural elements and forms	110	(14)
Structural elements	110	(6)
Single-leaf walls	110	(1)
Double-leaf collar-jointed walls	110	(1)
Double-leaf cavity walls	110	(1)
Double-leaf grouted cavity walls	110	(1)
Faced walls	111	(1)
Veneered walls	111	(1)
Walls with improved section modulus	111	(2)
Reinforced walls	113	(1)
Post-tensioned walls	114	(1)
Columns	114	(1)
Arches	115	(1)
Circular and elliptical tube construction	116	(1)
Composite construction	116	(1)
Horizontally reinforced masonry	116	(1)
Structural forms	116	(8)
Chimneys	116	(2)
Crosswall construction	118	(1)
Cellular construction	119	(1)
Column and plate floor construction	119	(1)
Combined forms of construction	120	(1)
Diaphragm wall and plate roof construction	121	(1)
Fin wall and plate roof construction	121	(1)
Miscellaneous wall and plate roof construction	121	(1)
Spine wall construction	121	(1)
Arch and buttressed construction	122	(1)
Compression tube construction	123	(1)
Design of masonry elements (1): Vertically loaded	124	(18)
Principle of design	124	(1)
Estimation of element size required	124	(1)
Sequence of design	124	(1)
Design of solid walls	124	(6)
Design of cavity walls	130	(4)
Ungrouted cavity walls	130	(2)
Grouted cavity walls	132	(2)
Double-leaf (or collar-jointed) walls	134	(1)
Design of walls with stiffening piers	134	(2)
Masonry columns	136	(2)
Diaphragm walls	138	(2)
Concentrated loads	140	(2)
Design of masonry elements (2): Combined bending and axial loading	142	(31)
Method of design	142	(31)
Design of single-storey buildings	173	(5)
Design considerations	173	(4)
Design procedure	177	(1)
Fin and diaphragm walls in tall single-storey buildings	178	(36)
Comparison of fin and diaphragm walls	179	(1)
Design and construction details	180	(1)
Architectural design and detailing	181	(2)
Services	182	(1)
Sound and thermal insulation	183	(1)
Damp proof courses and membranes	183	(1)
Cavity cleaning	183	(1)
Structural detailing	183	(3)
Foundations	184	(1)
Joints	184	(1)
Wall openings	185	(1)
Construction of capping beam	185	(1)
Temporary propping and scaffolding	185	(1)
Structural design: General	186	(5)
Design principles: Propped cantilever	186	(1)
Calculate design loadings	187	(1)
Consider levels of critical stresses	188	(1)
Design bending moments	188	(2)
Stability moment of resistance, MRs	190	(1)
Shear lag	190	(1)
Principal tensile stress	190	(1)
Design symbols: Fin and diaphragm walls	191	(1)
Fin walls: Structural design considerations	191	(2)
Interaction between leaves	191	(1)
Spacing of fins	191	(1)
Size of fins	192	(1)
Effective section and trial section	192	(1)
Example 1: Fin wall	193	(9)
Design problem	193	(1)
Design approach	194	(1)
Characteristic loads	194	(1)
Design loads	194	(1)
Design cases (as shown in Figure 13.42)	194	(1)
Deflection of roof wind girder	194	(2)
Effective flange width for T profile	196	(1)
Spacing of fins	196	(1)
Trial section	196	(1)
Consider propped cantilever action	197	(1)
Stability moment of resistance	197	(1)
Allowable flexural compressive stresses, pubc, taking into account slenderness, β, and material, γm	197	(2)
Calculate MR and compare with Mb	199	(1)
Bending moment diagrams	200	(1)
Consider stresses at level of Mw	200	(1)
Design flexural stress at Mw levels	201	(1)
Consider fins and deflected roof prop	202	(1)
Diaphragm wall: Structural design considerations	202	(5)
Determination of rib centres, Br	202	(2)
Depth of diaphragm wall and properties of sections	204	(1)
Shear stress coefficient, K1	205	(1)
Trial section coefficients, K2 and Z	206	(1)
Example 2: Diaphragm wall	207	(4)
Design problem	207	(1)
Characteristic and design loads	207	(1)
Select trial section	208	(1)
Determine wind and moment MRs at base	208	(1)
Consider stress at level Mw	209	(1)
Consider diaphragm with deflected roof prop	210	(1)
Calculate shear stress	211	(1)
Stability of transverse shear walls	211	(1)
Summary	211	(1)
Other applications	211	(3)
Design of multi-storey structures	214	(29)
Structural forms	214	(5)
Stability	215	(1)
External walls	215	(1)
Provision for services	216	(1)
Movement joints	216	(1)
Vertical alignment of loadbearing walls	217	(1)
Foundations	218	(1)
Flexibility	218	(1)
Concrete roof slab/Loadbearing wall connections	218	(1)
Accidental damage	218	(1)
Choice of brick, block and mortar strengths	219	(1)
Crosswall construction	219	(5)
Stability	219	(1)
External cladding panel walls	220	(1)
Design for wind	221	(1)
Openings in walls	222	(1)
Typical applications	222	(2)
Elevational treatment of crosswall structures	224	(1)
Podiums	224	(1)
Spine construction	224	(2)
Lateral stability	225	(1)
Accidental damage	226	(1)
Cellular construction	226	(2)
Comparison with crosswall construction	227	(1)
Envelope (cladding) area	227	(1)
Robustness	227	(1)
Flexibility	227	(1)
Height of structure	227	(1)
Masonry stresses	227	(1)
Foundations	228	(1)
Column structures	228	(1)
Advantages	228	(1)
Cross-sectional shape	228	(1)
Size	229	(1)
Design procedure	229	(1)
Example 1: Hotel bedrooms, six floors	229	(7)
Characteristic loads	229	(2)
Design of internal crosswalls	231	(1)
Partial safety factor for material strength (Table 4, BS 5628 -- see Table 5.11)	232	(1)
Choice of brick in the two design cases, at ground floor level	232	(1)
Choice of brick in the two design cases, at third flood level	232	(1)
Design of gable cavity walls to resist lateral loads due to wind	232	(1)
Uplift on roof	232	(1)
Design of wall	232	(1)
Calculation of design wall moment	233	(1)
Resistance moment of wall (Figure 14.46)	233	(1)
Overall stability check	233	(2)
Eccentricity of loading	235	(1)
Accidental damage	235	(1)
Example 2: Four-storey school building	236	(2)
Characteristic loads	237	(1)
Design of wall at ground floor level	237	(1)
Example 3: Four-storey office block	238	(5)
Column structure for four-storey office block	238	(1)
Characteristic loads	239	(1)
Design of brick columns	239	(1)
Loading on column P	239	(4)
Reinforced and post-tensioned masonry	243	(51)
General	244	(5)
Design theory	244	(1)
Comparison with concrete	244	(1)
Applications	245	(1)
Prestressing	246	(1)
Methods of reinforcing walls	246	(1)
Composite construction	247	(1)
Economics	247	(1)
Corrosion of reinforcement and prestressing steel	247	(1)
Cover to reinforcement and prestressing steel	248	(1)
Cover	248	(1)
Choice of system	249	(1)
Design of reinforced brickwork	250	(7)
Partial factors of safety	250	(1)
Strength of materials	251	(1)
Design for bending: Reinforced masonry	251	(1)
Lateral stability of beams	251	(1)
Design formula for bending: Moments of resistance for reinforced masonry	252	(3)
Design formula: Shear stress	255	(1)
Shear reinforcement	255	(1)
Design formula: Local bond	256	(1)
Characteristic anchorage bond strength, fb	256	(1)
Design for axial loading	256	(1)
Example 1: Design of reinforced brick beam	257	(2)
Example 2: Alternative design for reinforced brick beam	259	(2)
Example 3: Reinforced brick retaining wall	261	(1)
Example 4: Column design	262	(1)
Design of post-tensioned brickwork	263	(6)
General	263	(2)
Post-tensioned masonry: Design for flexure	265	(1)
Design strengths	266	(1)
Steel stresses	267	(1)
Asymmetrical sections	267	(1)
Losses of post-tensioning force	268	(1)
Bearing stresses	269	(1)
Deflection	269	(1)
Partial safety factor on post-tensioning force	269	(1)
Example 5: High cavity wall with wind loading	269	(6)
Capacity reduction factor, β	270	(1)
Characteristic strengths	270	(1)
Design strengths (after losses)	271	(1)
Section modulus of wall	271	(1)
Design method	271	(1)
Calculation of required post-tensioning force	271	(1)
Consider compressive stresses: After losses	272	(2)
Consider compressive stresses: Before losses	274	(1)
Design of post-tensioning rods	274	(1)
Example 6: Post-tensioned fin wall	275	(9)
Design procedure	275	(1)
Design post-tensioning force and eccentricity	276	(1)
Characteristic strengths	277	(1)
Loadings	277	(1)
Design bending moments	278	(1)
Theoretical flexural tensile stresses	278	(1)
Calculations of P and e	278	(1)
Spread of post-tensioning force	279	(1)
Characteristic post-tensioning force pk	279	(1)
Capacity reduction factors, β	279	(1)
Check combined compressive stresses	279	(3)
Design flexural compressive strengths of wall: After losses	282	(1)
Check overall stability of wall	282	(2)
Design of post-tensioning Rods	284	(1)
Example 7: Post-tensioned brick diaphragm retaining wall	284	(10)
Design procedure	284	(1)
Design loads	285	(1)
Trial section	286	(3)
Calculate theoretical flexural tensile stresses	289	(1)
Minimum required post-tensioning force based on bending stresses	289	(1)
Characteristic post-tensioning force, Pk	289	(1)
Capacity reduction factors	289	(1)
Check combined compressive stresses	290	(1)
Check shear between leaf and cross-rib	291	(2)
Design of post-tensioning rods	293	(1)
Arches	294	(13)
General design	294	(5)
Linear arch	295	(1)
Trial sections	296	(1)
Mathematical analysis	297	(2)
Design procedures	299	(1)
Design examples	299	(8)
Example 1: Footbridge arch	299	(2)
Example 2: Segmental arch carrying traffic loading	301	(3)
Example 3: Repeat Example 2 using a pointed arch	304	(3)
Appendix 1 Materials	307	(7)
A1.0 Introduction	307	(1)
A1.1 Clay masonry units (clay bricks)	307	(2)
A1.1.1 Sizes	307	(1)
A1.1.2 Classification	307	(1)
A1.1.3 Strength and durability	308	(1)
A1.1.4 Testing	309	(1)
A1.2 Calcium silicate units (bricks)	309	(1)
A1.3 Concrete bricks	310	(1)
A1.4 Stone units (stonework)	310	(1)
A1.5 Concrete units (blocks and bricks)	310	(1)
A1.5.1 Sizes	310	(1)
A1.5.2 Classification	310	(1)
A1.5.3 Density	310	(1)
A1.5.4 Form	310	(1)
A1.5.5 Strength	310	(1)
A1.5.6 Durability	310	(1)
A1.6 Mortars	311	(3)
A1.6.1 Constituents	311	(1)
A1.6.2 Choice of mortar	312	(1)
A1.6.3 Proportioning and mixing	312	(1)
A1.6.4 Testing	312	(2)
Appendix 2 Components	314	(3)
A2.1 Wall ties	314	(1)
A2.2 Damp proof courses	314	(1)
A2.3 Fixings	314	(1)
A2.4 Brick bonds	315	(2)
Appendix 3 Movement joints	317	(7)
A3.1 Movement due to thermal expansion and contraction	318	(1)
A3.2 Movement due to moisture	318	(2)
A3.2.1 Fired clay units	318	(1)
A3.2.2 Concrete and calcium silicate units	319	(1)
A3.3 Movement due to chemical interaction of materials (sulphate attack)	320	(1)
A3.4 Differential movement with dissimilar materials and members	320	(1)
A3.5 Foundation settlement	321	(1)
A3.6 Movement of joints and accommodation of movement	322	(1)
A3.7 Jointing materials and typical details	323	(1)
A3.8 Mortars in assisting movement control	323	(1)
Appendix 4 Provision for services	324	(3)
Index	327