Issue 36

H. Zhu, Frattura ed Integrità Strutturale, 36 (2016) 191-200; DOI: 10.3221/IGF-ESIS.36.19 193 Figure 2 : Vertical deformation of concrete under continuous load and drying effect. Shear capacity of steel reinforced concrete structure Before initial cracking, concrete in steel reinforced concrete joints plays a function of shear resistance [12]. As load increases, diagonal crack forms along the diagonal line of joints and then diagonal strut comes into being. Anti-shear capacity of concrete in steel reinforced concrete joints can be expressed as: c j j c V b h f   (1) where f c refers to compressive strength of axis of concrete; generally, joint section height h j is equal to column section height h, i.e., h c = h j ; b j stands for surface width of joint core area; γ stands for an undetermined coefficient which reflects anti-shear capacity of concrete in steel reinforced concrete joints under various constraints. To obtain the specific value of anti-shearing coefficient γ, the following formula is used. t j s sv j j c V V V b h f     (2) where t j V stands for measured ultimate bearing capacity of joints; s V stands for actual strength of material; sv V stands for bearing capacity of section steel web and hooping of joints. F ACTORS INFLUENCING CRACK FORMATION OF STEEL REINFORCED CONCRETE STRUCTURE UNDER STRESS IN CONSTRUCTION PERIOD Construction load onstruction load can be divided into construction dead load, construction live load and accidental load according to action time, and can be divided into vertical loading, horizontal loading, additional vertical load and special load according to action direction. Creep of concrete Creep of concrete refers to plastic deformation of concrete under single-axial stress effect along stress direction as time goes on [13]. Creep is composed of basic creep and drying creep. Ignoring the fact that creep deformation is larger than deformation of dried concrete under loading effect, creep is considered as a kind of deformation which has exceeded free shrinkage under loading effect (Fig. 3). Major factors influencing creep included exerted stress, water cement ratio, curing condition, temperature, humidity, cement composite, aggregate, chemical admixture, geometrical shape of test specimen and loading age. C