R3 - galvanised to a coating weight of at least 470g/m2 on both sides, in accordance with AS/NZS 4680 R4 - stainless steel grade AS 1449/316 or Think Brick Australia Manual 2, Section 3, The Properties of Clay Masonry Units provides further information on the durability of bricks. Brick Properties Brick Technical Manual 8 Fretting of Brickwork (Salt Attack) Fretting of brickwork is linked to the durability of bricks and directly related to the exposure environment in which they are placed. The fretting (flaking or crumbling) of bricks can be prevented by the adequate maintenance of the wall structure. An extreme case of fretting is shown below. Fretting is caused by the action of salt migration in the walling system. Water which has salt dissolved in it migrates through the brick to the brick surface. As the brick dries, the salt is left behind and forms a salt crystal. The salt crystals grow in the voids within the brick. As more salt is left behind by the evaporation of water, the salt crystal grows larger and larger. The strength of the growing salt crystal can be stronger than the elements that hold the brick together. If this occurs, the brick face begins to crumble and fall away. This is also the case for mortar joints.


y/
c 


y/
c w, pw, 
w
reinforcement indices for flanged sections, computed as for , p, and 
, except that b is the web width, and the reinforcing steel area is that required to develop the compressive strength of the web only Design and Cracking Loads. To prevent an abrupt flexural failure by rupture of the prestressing steel immediately after cracking without a warning deflection, the total amount of prestressed and nonprestressed reinforcement should be adequate to develop a factored load in flexure of at least 1.2 times the cracking load, calculated on the basis of a modulus of rupture r. For normal-weight concrete, this modulus may be taken as
7.5

(9.126) r c and for lightweight concrete as
1.12  7.5

(9.127) r ct c where ct
average splitting tensile strength of lightweight concrete. When the value for ct is not available, the modulus of rupture of lightweight concrete can be computed for sand-lightweight concrete from
6.375

(9.128) r c and for all-lightweight concrete from
5.625

(9.129) r c (PCI Design Handbook, Precast / Prestressed Concrete Institute.) The ACI 318 Building Code requires that prestressed concrete beams be designed to resist diagonal tension by strength theory. There are two types of diagonal-tension cracks that can occur in prestressed-concrete flexural members: flexural-shear cracks initiated by flexural-tension cracks, and web-shear cracks caused by principal tensile stresses that exceed the tensile strength of the concrete. The factored shear force Vu computed from Eq. (9.38) can be used to calculate the diagonal-tension stress. The distance d from the extreme compression surface to the centroid of the tension reinforcement should not be taken less than 0.80 the overall depth h of the beam. When the beam reaction in the direction of the applied shear introduces compression into the end region of the member, the shear does not need to be checked within a distance h/2 from the face of the support. Minimum Shear Reinforcement. The ACI 318 Building Code requires that a minimum area of shear reinforcement be provided in prestressed-concrete members, except where the factored shear force Vu is less than 0.5Vc, where Vc is the assumed shear that can be carried by the concrete; or where the depth h of the member is less than 10 in, 2.5 times the thickness of the compression flange, or one-half the thickness of the web; or where tests show that the required nominal (ultimate) flexural and shear capacity can be developed without shear reinforcement. When shear reinforcement is required, the amount provided perpendicular to the beam axis within a distance s should be not less than Av given by Eq. (9.81). If, however, the effective prestress force is equal to or greater than 40% of the tensile strength of the flexural reinforcement, a minimum area Av computed from Eq. (9.130) may be used. Aps pu s d Av
 (9.130) 80 d b y w where Aps
area of tendons in tension zone pu
ultimate (tensile) strength of tendons y
yield strength of nonprestressed reinforcement s
shear reinforcement spacing measured parallel to longitudinal axis of

Wall Ties Wall ties should be placed every Wall ties should be placed every 5th course for the 76mm Designa Basalt 2nd course for the 162mm Designa Basalt Design Considerations Brick Technical Manual 71 Internal non-loadbearing wall Designa Basalt at 70mm thick cannot be used as a single leaf internal wall. Internal non-loadbearing walls need to satisfy the 0.5kPa lateral load Figure 13 Typical Internal Wall Suspended Slab Detail 470x70x162 FACE Figure 14 Typical Internal Wall Detail 470x70x162 FACE requirements as set out in AS 3700. To satisfy this requirement, Designs Basalt must be constructed as a solid wall combined with a 90mm brick. Typical details are shown below. Design Considerations Brick Technical Manual 72 Internal Wall Design Consult graph 1-5 for the dimensions of the walls. When Designa Basalt is laid as a solid wall For stack bond, only graph 1 Laterally supported combined with regular 90mm bricks in a stretcher top only applies. bond manner, the dimensions of the wall are dictated by the amount of support the wall has. Chart 6 Wall is laterally supported from the top only