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Through the intelligent casting practice of immersed tube of Shenzhen -Zhong shan Link, information means were effectively used to assist construction, and intelligent equipment wholly or partially replaced complicated manual operations. The manual and semi -automatic control of the original concrete pouring is promoted to intelligent equipment and system, which effectively improves the pouring quality, reduces the loss of concrete, greatly improves the work efficiency, saves on-site operators, improves the project management level, and can provide intelligent solutions for the subsequent casting of super large concrete components. [ABSTRACT FROM AUTHOR]

In view of the fact that the water depth at the front of Q27 sheet pile wharf of Ashdod Port is nearly 18 m, it is easy to have the characteristics of poor fluidity, poor segregation resistance, low filling rate and serious pipe blockage in the construction of concrete mattress. Based on the Israeli design code, a mix ratio for the B30 concrete mattress to apply to the bottom protection of deepwater wharf apron was designed. The proportion of raw materials was initially given by considering characteristics of raw materials and European codes. The flow cone trial was used to test the fluidity and segregation performance of different mix proportion groups of concrete. Combined with the field underwater trial of concrete mattress, the flow-ability, filling rate and compressive strength were further tested. It was determined that the rubber hose with diameter of 63 mm and length of 80 m was used to pump the concrete, and the maximum pumping rate should not exceed 25 m3 /h. It can provide references for the practical construction of deep-water concrete mattress. [ABSTRACT FROM AUTHOR]

Shenzhen-Zhongshan Link is a magnificent cluster project integrating bridge, artificial island, immersed tunnel and under-water crossing interchange. The steel shell-concrete composite structure is adopted for subsea immersed tunnel for the first time in China, which is facing a technological gap in the entire industry chain. Based on the regulatory management on construction conditions of the project, we systematically elaborated the overall design of steel shell -concrete immersed tube tunnels in terms of technical standards, overall layout, tube element structure, self -compacting concrete material preparation and working performance, fire prevention system and corrosion protection system. Relevant experience can be used for industry reference. [ABSTRACT FROM AUTHOR]

Taking the self-compacting concrete pouring of steel shell immersed tubes in Shenzhen-Zhongshan Channel as the research background, the workability of the self-compacting concrete mix ratio was verified by the single-bin scale model test, and the location and cause of the defects during the concrete pouring were grasped. The ratio of defect area and volume, the maximum / average defect depth, the main defect distribution and other parameters of the top surface of the concrete pouring were tested by using two-level grayscale processing method and the stone powder filling method, the larger defects are often concentrated near the blanking opening and the back of the top stiffener, which provides data support for the subsequent construction of the steel shell immersed tube self-compacting concrete. [ABSTRACT FROM AUTHOR]

We discussed the history, development drive, properties, mechanism, mixture design and quality inspection test of the self-consolidating concrete (SCC) . With the experience from the design and construction preparation of Hongkong- Zhuhai -Macao Bridge project immersed tunnel closure joint, we discussed the critical issue of SCC in the design and construction of immersed tunnel. The conclusion was drawn that as long as SCC is chosen, the SCC should not just be regarded as a material but as a construction technique, the design -construction contract allows the freedom of utilizing the SCC advantage. [ABSTRACT FROM AUTHOR]

With quasi-static tests, the seismic performance of five precast NC composite shear walls infilling SCC and two precast NC composite shear walls infilling NC were studied. The effects of wall boundary element, axial compression ratio, and insulating layer were considered. The bearing capacity, failure pattern, hysteretic loops, skeleton curves, rigidity degradation curves, ductility and energy dissipation of precast NC composite shear walls infilling SCC were investigated. The two types of composite shear wall were compared infilling SCC and NC. The results indicate that the precast composite shear walls infilling SCC have good seismic behavior. The prefabricated parts and the cast-in-place SCC parts of the composite shear walls with steel support can work together in coordination very well under loading. The carrying capacity of composite shear wall infilling SCC is not lower than that infilling NC. The failure mode, crack distribution, hysteretic curve, energy dissipation capacity and stiffness degradation for two types of composite shear wall are similar. The ductility of the precast composite shear walls infilling SCC is a little better than the precast composite shear walls infilling NC. Increasing axial compression ratio from 0.1 to 0.2 will help improving the carrying capacity of walls. Using the embedded column will improve the whole performance of the precast composite shear walls infilling SCC. [ABSTRACT FROM AUTHOR]

A new composite strengthening method where the RC column was strengthened with serf-compacting concrete filled circular steel jacket was presented. Mechanical properties of two RC columns, two RC columns strengthened by enlarging cross-section method and nine RC columns strengthened with serf-compacting concrete filled circular steel jacket subjected to axial loading were investigated. The influences of loading mode, steel ratio, compressive strength of strengthening self-compacting concrete and interface bond on bearing capacity, stiffness and ductility of strengthened columns were analyzed. Test results show that the bearing capacity and ductility of the composite strengthened columns are significantly better than the columns strengthened by enlarging cross-section and the RC column. The load bearing capacity of composite strengthened columns with loading on only core concrete is slightly better than those with loading on full section. With the steel ratio increasing, composite strengthened columns show a significant increasing trend in the load bearing capacity and ductility. With the compressive strength of strengthening concrete increasing, composite strengthened columns show a slight increasing trend in the load bearing capacity but a decreasing trend in ductility. The mechanical property subjected to axial loading of composite strengthened columns is not affected by interface bond. Based on the results, a formula was proposed to calculate the load bearing capacity of the composite strengthened short columns. The calculating results agree with the experimental results well. [ABSTRACT FROM AUTHOR]

The bond characteristics between serf-compacting concrete and reinforcement are worth researching due to material constitution and no need of vibration. The local bond characteristics between self-compacting concrete and reinforcement were analyzed experimentally and test parameters included self-compacting concrete strength and loading pattern. The tests were conducted on ten specimens under monotonic loading and ten specimens under repeated loading, including sixteen serf-compacting concrete specimens and four common concrete specimens. Reinforcement of all specimens was pulled out by electro hydraulic servo device. The local bond stress between serf-compacting concrete and reinforcement was analyzed including bond stress uneven coefficient and residual bond stress distributions. The bond stress distribution curve shows wavy under repeated while single crest under monotonic load. The bond stress distribution is more uneven with concrete strength increasing but more even with cyclic loading and number of cycles increasing. When each level unloading, the residual bond stress is larger with concrete strength increasing and its distribution range transfers to free end with cyclic load and number increasing. The bond performance between serf-compacting concrete and reinforcement is a little better than normal concrete. Based on the results, the regression equations for local bond stress position function under monotonic loading and repeated loading were obtained and were validated by test results. The regression equations agree with the test results. [ABSTRACT FROM AUTHOR]

Sixteen steel fiber reinforced self-compacting concrete (SFRSCC) beams were tested to investigate the influence of steel fibers and the combined effect of fibers and stirrups on the deflection, ultimate loads, equivalent shear strength and failure mode. The experiment indicates that the shear strength and equivalent shear strength increases clearly with the increasing of fiber content. This study also examined the feasibility of applying the modified compression field theory (MCFT) for the suitable assessment of shear resistance in fiber and steel rebar reinforced self-compacting concrete beams. Compared with the Rilem recommendation TCF162 and CECS 38:2004, the proposed method has a good fit with the test results. So it is suitable for shear analysis and design of SFRSCC beams. [ABSTRACT FROM AUTHOR]