Problems in Design of Reinforced Concrete Structures

　　1结构体系不合理

　　1. unreasonable structure system

　　钢筋混凝土结构在进行设计时，设计人员需要结合工程结构特点，同时参考抗震等级以及风荷载情况，选择合理的结构体系。但是，如果选择的结构体系不合理，将会影响结构的稳定性，使其结构性能降低，如果设计人员选择的设计指标不科学，也将会降低结构设计的可行性和科学性，导致建筑质量出现问题，甚引发事故。

　　In the design of reinforced concrete structures, designers need to choose a reasonable structure system according to the characteristics of Engineering structures, seismic grade and wind load. However, if the selected structural system is not reasonable, it will affect the stability of the structure and reduce its structural performance. If the design indicators chosen by the designers are not scientific, it will also reduce the feasibility and scientificity of the structural design, resulting in problems in building quality and even lead to safety accidents.

　　2下部结构设计中存在的问题

　　2. Problems in the design of substructure

　　（1）地下室底板设计。由于建筑上部结构受到的荷载致使柱下独立基础和地下室顶板发生沉降变形。设计时如果对这种情况不能引起足够的重视，则会导致地下室顶板承受压力过大，超过极限后极容易发生断裂现象，导致建筑发生倾斜甚结构断裂。（2）地下室底板配筋不合理。地下室作为基础结构的一部分，具有增强建筑物结构的稳定性、承载能力以外，还能削减地震破坏程度。在地下室设计时，若地下室底板配筋不合理，会导致钢筋混凝土结构出现失稳现象，增加建筑物的不均匀沉降量。（3）天然基础设计不合理。在对天然地基中的独立基础进行设计时，采用了不合理的设计，斜面坡度大于1:3，这使得地基混凝土振捣不密实，影响振捣质量，影响地基结构的稳定性。实际施工过程中，常运用人工振捣拍打的方式振捣混凝土，但是振捣质量不易控制，甚不能达到设计要求强度。（4）地下水位的影响。在钢筋混凝土结构设计中，地下水位的影响对其结构的稳定性影响较大，在设计过程中应尤其注意地下水位变化较大的地方，重视建筑防水及降水问题，对建筑工程施工进度以及质量控制有重要的作用。同时，整个建筑基础结构设计中，基础受到上部结构荷载作用，一旦发生沉降变化，地下室顶板和柱子将共同受力。

　　(1) Basement floor design. Because of the load on the superstructure of the building, the settlement and deformation of the independent foundation under the column and the roof of the basement occur. If we do not pay enough attention to this situation in design, it will cause the basement roof to bear too much pressure, and it will easily break after exceeding the limit, leading to the inclination of the building and even structural fracture. (2) The reinforcement of basement floor is unreasonable. Basement, as a part of infrastructure, can not only enhance the stability and bearing capacity of building structure, but also reduce the degree of earthquake damage. In basement design, unreasonable reinforcement of basement floor will lead to instability of reinforced concrete structures and increase the uneven settlement of buildings. (3) The design of natural foundation is unreasonable. In the design of independent foundation in natural foundation, unreasonable design is adopted. The slope is more than 1:3, which makes the vibration of foundation concrete not compact, affects the quality of vibration, and affects the stability of foundation structure. In the actual construction process, manual vibration is often used to vibrate concrete, but the quality of vibration is not easy to control, or even can not meet the design strength requirements. (4) The influence of groundwater level. In the design of reinforced concrete structure, the influence of groundwater level has a great influence on the stability of its structure. In the design process, special attention should be paid to the place where the groundwater level changes greatly, and attention should be paid to the waterproof and dewatering of buildings, which plays an important role in the construction progress and quality control of construction projects. At the same time, in the design of the whole building foundation structure, the foundation is subjected to the load of the superstructure. Once the settlement changes, the basement roof and the pillar will bear the force together.

　　上部结构设计中存在的问题

　　Problems in Superstructure Design

　　在钢筋混凝土结构设计中，上部结构相对与下部结构来说，理论较为成熟，存在的问题也相对较少，主要体现在三个方面：，框架剪力墙设计时，如果设计不合理，则会导致应力较为集中，威胁建筑结构的性，当发生地震时，建筑结构容易出现坍塌，另外，剪力墙分布不均也会增加框架剪力墙连接构件的设计难度，不利于建筑结构的稳定性和可靠性。其次，在以钢筋混凝土结构为主的建筑中，抗侧力主要的构件是钢筋混凝土，因此，钢筋混凝土结构测量位移必须要满足规定的侧向位移限值，如果超过限值，将会导致建筑结构的稳定和受到影响。后，裂缝问题是钢筋混凝土工程中不可忽视的部分，分为构造裂缝和结构裂缝，其中构造裂缝是由于施工技术人员操作不当或者不规范导致的，如混凝土振捣不充分、水灰比不合理、养护不到位，模板位置改变或者过早脱模等均会导致构造裂缝的发生。而结构裂缝出现在钢筋混凝土结构的浇筑过程中，这是由于不同构件之间的刚度存在差异，形成了刚度薄弱区域，导致结构中出现裂缝，常见于楼板顶端或者墙角等位置。

　　In the design of reinforced concrete structures, the theory of superstructure is relatively mature and the existing problems are relatively few, which are mainly reflected in three aspects: first, if the design of frame shear wall is unreasonable, it will lead to more concentrated stress and threaten the safety of the building structure. When earthquake occurs, the building structure is prone to collapse. The uneven distribution of shear walls will also increase the difficulty in the design of frame-shear wall connections, which is not conducive to the stability and reliability of building structures. Secondly, in the building with reinforced concrete structure as the main component, the most important component to resist lateral force is reinforced concrete. Therefore, the measured displacement of reinforced concrete structure must meet the prescribed lateral displacement limit. If it exceeds the limit, the stability and safety of the building structure will be affected. Finally, the problem of cracks is an important part in reinforced concrete engineering, which can be divided into structural cracks and structural cracks. The structural cracks are caused by improper or non-standard operation of construction technicians, such as inadequate vibration of concrete, unreasonable water-cement ratio, inadequate maintenance, change of template position or premature demoulding. The structural cracks occur in the pouring process of reinforced concrete structure, which is due to the stiffness difference between different components, forming a weak stiffness area, resulting in cracks in the structure, often at the top of the floor or corner.

　　4结构抗震设计存在的问题

　　Existing Problems in Seismic Design of 4 Structures

　　钢筋混凝土结构设计时，一定要考虑结构的抗震性能等级，这对建筑的使用具有十分重要的意义。地震是较为常见的自然灾害，其对建筑结构的影响是由内而外的，地震纵波对建筑物结构施加作用力，导致坚固的结构外表出现松动等、裂缝等变化，严重威胁着建筑结构的稳定性。虽然我国不是地震频发的，但近几年几场较大地震灾害的发生以及以往的经验也表明了，具有高抗震等级的建筑物在地震中稳固性和性相对较高，因此，提高建筑物的抗震性能是当前人们关注的。由于钢筋混凝土结构本身具有的特性，使其抗震性能较低，这也是当前需要的问题。

　　In the design of reinforced concrete structures, the seismic performance grade of structures must be considered, which is of great significance to the safety of buildings. Earthquakes are common natural disasters, which affect the structure of buildings from the inside to the outside. The longitudinal wave of earthquakes exerts a force on the structure of buildings, resulting in changes in the appearance of solid structures such as loosening, cracks and so on, which seriously threatens the stability of building structures. Although China is not a country with frequent earthquakes, the occurrence of several major earthquake disasters in recent years and past experience also show that buildings with high seismic grade have relatively high stability and safety in earthquakes. Therefore, improving the seismic performance of buildings is the focus of current attention. Because of the characteristics of reinforced concrete structure itself, its seismic performance is low, which is also a key problem to be solved at present.