混凝土分部工程施工质量监督中的关键控制要点分析

混凝土分部工程作为建筑工程的重要组成部分,其施工质量直接关系到工程的安全性和耐久性。本文分析了混凝土分部工程施工质量监督中的关键控制要点,探讨了影响混凝土质量的主要因素,并提出了具体的质量控制策略。通过严格控制混凝土配合比、加强原材料的质量管理、完善施工工艺及加强质量检测与监督,能够有效提升混凝土分部工程的施工质量,确保工程的顺利进行和长期使用性能。

混凝土分部工程质量验收常用评定方法分析

对比分析了标准养护试块、同条件养护试块、回弹法、超声回弹法、钻芯法及后装拔出法等常用评定方法验收混凝土分部工程质量的原理及局限性,结合具体工程试验数据,分析常用评定方法的测试精度,提出针对不同工程验收问题,采取合适的验收评定方法,能够进一步强化工程项目验收,保证混凝土质量。

现代工业厂房混凝土分部质量控制

现代工业厂房是现代工业的生产空间和工艺载体,现代工业的新型化、高技术化、高信息化趋势,对厂房结构施工质量提出更高的要求。本文主要对现代工业厂房结构混凝土施工时的质量控制进行了探讨。

Seismic performance of double-skin steel-concrete composite box piers: Part Ⅱ—Nonlinear finite element analysis

An accurate finite element （ FE） model was constructed to examine the hysteretic behavior of double-skin steel-concrete composite box （ DSCB） piers for further understanding the seismic performance of DSCB piers; where the local buckling behavior of steel tubes, the confinement of the in-filled concrete and the interface action between steel tube and in-filled concrete were considered. The accuracy of the proposed FE model was verified by the bidirectional cyclic loading test results. Based on the validated FE model, the effects of some key parameters, such as section width to steel thickness ratio, slenderness ratio, aspect ratio and axial load ratio on the hysteretic behavior of DSCB piers were investigated. Finally, the skeleton curve model of DSCB piers was proposed. The numerical simulation results reveal that the peak strength and elastic stiffness decrease with the increase of the section width to steel thickness ratio. Moreover, the increase of the slenderness ratio may result in a significant reduction in the peak strength and elastic stiffness while the ultimate displacement increases. The proposed skeleton curve model can be taken as a reference for seismic performance analyses of the DSCB piers.

Nonlinear behavior of concrete beams with hybrid FRP and stainless steel reinforcements

The full-range behavior of partially bonded, together with partially prestressed concrete beams containing fiber reinforced polymer （FRP） tendons and stainless steel reinforcing bars was simulated using a simplified theoretical model. The model assumes that a section in the beam has a trilinear moment--curvature relationship characterized by three particular points, initial cracking of concrete, yielding of non-prestressed steel, and crushing of concrete or rupturing of prestressing tendons. Predictions from the model were compared with the limited available test data, and a reasonable agreement was obtained. A detailed parametric study of the behavior of the prestressed concrete beams with hybrid FRP and stainless steel reinforcements was conducted. It can be concluded that the deformability of the beam can be enhanced by increasing the ultimate compressive strain of concrete, unhonded length of tendon, percentage of compressive reinforcement and partial prestress ratio, and decreasing the effective prestress in tendons, and increasing in ultimate compressive strain of concrete is the most efficient one. The deformability of the beam is almost directly proportional to the concrete ultimate strain provided the failure mode is concrete crushing, even though the concrete ultimate strain has less influence on the load-carrying capacity.

Probabilistic Assessment of Pitting Corrosion Effect on Flexural Strength of Partial Prestressed Concrete Structures in a Chloride Environment

Like reinforced concrete （RC） structure, Prestressed concrete （PC） structures cannot escape from corrosion related problems, especially when they are subjected to very aggressive environment, such as chloride environment. The corrosion of PC and RC structures can take place if the concrete quality is not adequate, the concrete cover is less than that specified in the design, poor detailing during design and construction. For RC structures, corrosion in the reinforcing steel generally leads to serviceability problems （staining, cracking and spalling of concrete）. By contrast, for PC structures, corrosion of prestressing strands may initiate structural collapse due to higher stress levels in the steel and smaller diameter of the prestressing steel. Research on corrosion effect on concrete structure has mainly considered the effect of corrosion have on reinforced and full prestressed concrete structure. In this study, a structural framework will be developed to predict the flexural strength of partial prestressed concrete structures in a chloride environment. The corrosion model previously developed for reinforced and prestressed concrete structures will be combined to predict the effect of corrosion has on partial prestressed concrete structures. Note that in partial prestressed concrete structures, both non prestressing steel （passive） and prestressing （active） reinforcement are utilized to carry the load. The framework developed will be combined with probability analysis to take into account the variability of parameters influencing the corrosion process. This approach allows more accurate prediction of service life of partial prestressed concrete structures in a chloride environment.