Applied Mechanics and Materials Vols. 204-208

Abstract: There have been few reports on shear behavior of reinforced concrete (RC) beams with corroded stirrups, and the influence of stirrup corrosion has yet to be identified. Given this background, experience was carried out to investigate the shear behavior of RC beams containing corroded stirrups. Investigation results indicate that if the percentage local maximum mass loss is below 35%, there is little influence on the load-carrying mechanism. The concrete shear resistance seems to change little and the shear capacity can be calculated by just taking into consideration the reduction in stirrup shear resistance. It is also found that the anchorage conditions of the stirrups have a predominant influence on the shears of RC beams.

Abstract: In order to reflect the tertiary rheological characteristics of hard rocks at the high stress states, a new nonlinear visco-elastic-plastic model is proposed on the basis of linear visco-elastic-plastic model and nonlinear visco-elastic-plasticity. And then the corresponding constitutive model are deduced, which can be used for describing rocks’ long-term strength characteristics and their creep deformational behavior and time-dependent damage under interaction of coupled seepage-stress field in rock engineering. At last, considering the time effect of rock damage in the process of tertiary creep, a coupled seepage -stress creep damage model for investigating the whole creep deformation behavior, including tertiary creep failure process is established, and the related equations governing the evolution of stress, creep damage and rock permeability along with the creep deformation of rock is introduced.

Abstract: Concrete cracking sensitivity made from different aggregates was compared with employment of advanced temperature and stress test machine by tracking thermal and stress development of concrete with age and elements distribution in interfacial transition zone of each concrete was explored by SEM and EDS. Test results indicated that compressive strength of concrete made from basalt and limestone was greater than diorite and natural aggregate and crack resistance of concrete based on cracking sensitivity comparison in terms of cracking temperature varying from minus 0.3°C to minus 2.5°C as diorite, basalt, limestone and natural aggregate. Elements Ca and Mg were apparently accumulated in vicinity of ITZ and some reaction between limestone and cement matrix might have taken place which blurred the boundary between aggregates and cement matrix.

Abstract: In the latter part of concrete small-sized hollow block masonry cracks after using many reasons, including the design factors that are not in place, the material factors, construction factors, climate, natural conditions, factors, etc., in which the age of c concrete small-sized hollow block length of cracks in the masonry of the impact is different. Cracks in the masonry structure will cause adverse effects, affecting the use of construction and durability, this paper field test, to identify non-instars of concrete small-sized hollow block masonry cracks on impact. To reduce or prevent age of concrete hollow block the effects of crack, to strictly control the construction of block wall on the age, age as long as possible, especially in areas influenced by temperature, such as wall, the top wall, should pay attention to blocks of age, in a possible, concrete hollow block age should be greater than 42 days, the best age to block more than 56 days is better.

Abstract: A mechanical model of buried pipeline with frusta was established under the research of being collapse and gulch. A finite cell model of buried pipeline was built by using ANSYS finite cell analysis program. The seismic response of the finite cell model under the action of siesmic waves were simulated in different earthquake intensity，and its stress and distortion under static load and dynamic load of collapse and gulch was given, then the length of pipeline failure was given. the important foundation for the earthquake is provided by the simulated results.

Abstract: Many researchers study the seismic performance of shear wall embedded with reinforced concealed bracings, but not take the shape memory alloy bars concealed bracings into account. Quasi-static tests of a low shear wall with reinforced concealed bracings and a low shear wall with SMA bars concealed bracings are performed to study the seismic performance of the shear walls. Bearing capacity, stiffness, ductility, hysteretic energy and residual deformation of two specimens are researched and analyzed. The experimental results indicate that the SMA bars concealed bracings can increase the strength and ductility of the low shear wall considerably.

Abstract: Drying shrinkage loads are converted into the equivalent temperture,using the model of composite material mechanical analysised layer stresses and interlaminar stresses of the shear wall under the influence of temperture load stress,combined with wind load and weight ,acquired the thermal insulation layer’s stress effect under the combined effect. According the failure criterion of material and adhesive surface, to determined the cracking mechanism and crack control of aerated concrete thermal insulation layer.

Abstract: Abstract. Fiber-reinforced strain-hardening cement composite (SHCC) shows multiple cracking, higher tensile strain capacity and tensile strength than conventional concrete and fiber-reinforced cement composite (FRCC). These characteristics of SHCC materials improve crack-damage mitigation. Current application of SHCC materials includes bridge decks, building dampers, retaining wall, and irrigation channels. During SHCC’s hardening, higher shrinkage occurred because SHCC’s mixture is richer than conventional cement composite. In this study, an expansive admixture was utilized for SHCC mixture to control the shrinkage of SHCC materials. The objective of the study is to investigate the effect of cement composite’s ductility and shrinkage on the flexural and cracking behaviors of reinforced cement composite beams. Test result indicates that cement matrix’s ductility has a significant effect on the flexural and cracking behavior of reinforced cement composite beams and the phenomenon is remarkable for a beam with shrinkage-compensating SHCC replaced a part of cement by expansive admixture.

Abstract: Ultrasonic method is a considerably mature method to test the defects of concrete. As for a certain dam deep crack with merely one test surface, the operations can be done such as drilling holes on both crack sides, filling clean water as coupling agent and finally the crack depth is tested with cross-hole sonic logging, subsequently, the data processing and depth judgment with the test principle of the said method. The result manifests that before grouting treatment, the measured dam crack depth is 1.2~9.0m, and the tested point wave shape has not been obviously abnormal and the criterions of wave amplitude and wave speed against the intact local concrete remain no greater differences and the cracks grout in the tested zone are generally solid after the grouting.

Abstract: Based on the horizontal and vertical components of a set of 30 acceleration records obtained from 10 near-fault earthquakes, the horizontal and the vertical response spectra are established, and have been compared with each other in this study. Statistical analyses show that, for the selected 30 acceleration records, the maximum mean of vertical acceleration spectra is slightly higher than which of horizontal acceleration spectra. That means the near-fault earthquake really have significant vertical effect. Consulting the domestic and international research achievement, the normalized near-fault design spectrum adapted to Chinese seismic design Code (GB50011-2010) is established in horizontal direction. The results show that, within short period range, the horizontal near-fault design spectrum obtained in this paper is obviously higher than which derived from Chinese seismic code. Subsequently, the spectra of horizontal components for the selected 30 records are each scaled to match the horizontal near-fault design spectrum at two periodic points of 1.0 and 1.5 sec respectively, and the corresponding vertical spectra are scaled with the horizontal spectra at the same time. The scaled results reveal that the vertical spectra have much higher discretion than horizontal spectra, hence the study in this paper could initiates the research interest to a new aspect concerned with the randomness of vertical spectra for near-fault ground motions, which would affect the seismic reliability of structures significantly.