FOXBORO 0303440C脉冲输入通道模块

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FOXBORO 0303440C脉冲输入通道模块

在本系统中每个就地操作站都配有一台上位监控机，这台上位机不仅能操作本地站，在一定的授权下还能对其他站进行监视和控制。中控室配有二台上位监控机，他们能同时控制所有四个就地控制站，向其发送命令。这六个上位监控机之间的关系是互为功能备用的，这就是说这六个监控站中只要有一个发生故障，另外的五个监控站通过一定的授权就能代替该站的工作。系统中所有设备的电源均由UPS提供，每个仪表的电源都由开关型端子控制，能独立开关。保证了系统安全性，和调试的方便性。在前几年的住宅建设中,钢筋混凝土预制板是构成砖混结构房屋的重要构件,但是,其本身由于在构造上存在着一些致命的缺陷,即整体性及抗震性差,因此,在近几年的住宅建设中它逐步被钢筋混凝土现浇板所替代,但是,随着钢筋混凝土现浇板在房屋建设中的大量推广与应用,它的裂缝问题也越来越引起人们的注意。二.钢筋混凝土现浇板裂缝原因的分析笔者通过这些年对所接触到的钢筋混凝土现浇板裂缝问题的调查与分析,认为它主要是由以下几个方面的原因造成的:1)混凝土的收缩,2)混凝土的原材料质量,3)施工的质量,4)荷载的作用, 5)设备专业的影响,6)地基的不均匀沉降等.有时候,它的裂缝往往是由几个方面的原因共同作用所致。下面,笔者对这几个方面的原因逐一作简单的分析。 1.混凝土的收缩众所周知,混凝土引起收缩的原因,在硬化初期主要是由于水泥的水化作用,形成一种新的水泥结晶体,这种结晶体化合物较原材料体积小,因而引起混凝土体积的收缩,即所谓的凝缩,后期主要是混凝土内自由水蒸发而引起的干缩.而且,如果混凝土处在一个温差变化较大的环境下,将会使其收缩更为加剧。目前,以我市的住宅建设为例,钢筋混凝土现浇板中的裂缝,大部分是由于混凝土的收缩原因引起的.由于混凝土自身在硬化过程中存在凝缩和干缩,加上我市在一年中的气温相差较大,夏季高气温可超过35OC,而到冬季低气温达-10oC(参考有关资料),相差45o C,而混凝土的膨胀系数为10-5/0C,所以,经过一年的夏冬交替,混凝土的温差应变可达400uε以上,考虑到柱.墙对现浇板的约束系数为0.25---0.35,混凝土的结构温差应变约为60---110uε,因此,钢筋混凝土现浇板在这种情况下,很容易出现裂缝。 2.混凝土原材料的质量在住宅建设中,也有一部分钢筋混凝土现浇板出现的裂缝,是由于用来制作现浇板的原材料质量不合格所造成的.如水泥凝结或膨胀不正常,则产生既短又不规则的裂缝,这种裂缝多产生在混凝土硬化的早期;如果骨料中含泥量过多,则随着混凝土的干燥,会产生不规则的网状裂缝;有时碱----骨料反应,也会引起裂缝. 3.施工的缺陷在住宅建设中,有相当一部分的钢筋混凝土现浇板出现裂缝,是由于施工方面的原因造成的,这些原因包括以下几个方面:混凝土的强度等级达不到设计要求,现浇板的厚度不够,钢筋的放置不到位,配筋量的不足等均会造成现浇板的挠度过大,从而引起它在受弯抗拉处产生裂缝;刚浇筑的混凝土板也会因模板支撑下沉,使楼板挠度加大,拆模后也会出现裂缝;特别是对于阳台.雨蓬.挑檐等悬臂构件,往往由于工人在浇灌混凝土过程中,将板上的负弯矩钢筋踩倒,使构件不能承受负弯矩从而引起裂缝,严重的甚至于引起这些构件断裂。 4.荷载的作用在住宅建设中,也有少部分钢筋混凝土现浇板的裂缝,是由于荷载作用方面的原因引起的.由于设计人员在进行现浇板的配筋计算过程中,通常只是根据其承载能力来确定配筋量的,而往往忽略了对板在正常使用阶段由其承受的荷载而引起的挠度及裂缝宽度的验算,由此而引起裂缝的产生,这些裂缝有时也会超过规范的大允许值,这也应当引起足够的重视. 5.设备专业的影响在住宅建设中,钢筋混凝土现浇板的裂缝也有一部分是受设备专业的影响引起的.目前,在楼房的设计中,设备专业特别是电气专业,大多将照明.有线电视.通讯等所需的管线直接敷设于现浇板中,而且有时集中于某一处现浇板中的管线多达7----8根,并且这些管线的直径多为2---3CM,由此就会使该处的现浇板厚度大大削弱,从而引起现浇板在该处开裂. 6.地基的不均匀沉降在住宅建设中,也有相当一部分的钢筋混凝土现浇板的裂缝,是由于地基不均匀沉降的原因而造成的.以我市为例，我市的建筑场地约80%为软土场地,其层理构造一般为:表面1--1.5米为粘土,第二层为淤泥或淤泥质土.厚度为6--25米,其下为承载力较高的粘土层,故我市大部分四层以上的住宅均采用桩基,但也有相当一部分低于四层的住宅楼采用扩展基础,在我市的这种地质情况下,如果采用这种基础形式,则对于那些相对较长的条式楼来说,要想保正它们沉降均匀是相当困难的，因此,在这种情况下,有时也会由于基础的不均匀沉降,而引起楼房的拉裂和钢筋混凝土现浇板的开裂.In this system, each local operation station is equipped with an upper monitoring computer, which can not only operate the local station, but also monitor and control other stations under certain authorization. The central control room is equipped with two upper monitoring computers, which can simultaneously control all four local control stations and send commands to them. The relationship between the six upper monitoring computers is functional backup, which means that as long as one of the six monitoring stations fails, the other five monitoring stations can replace the work of the station with certain authorization. The power supply of all equipment in the system is provided by UPS. The power supply of each instrument is controlled by switch type terminals and can be switched independently. The system security and debugging convenience are guaranteed. In previous years' residential construction, the reinforced concrete precast slab is an important component of the brick concrete structure house. However, due to some fatal defects in its structure, namely poor integrity and seismic resistance, it has been gradually replaced by the steel reinforced concrete cast-in-situ slab in recent years' residential construction. However, with the massive promotion and application of the reinforced concrete cast-in-situ slab in housing construction, Its crack problem has also attracted more and more attention. II Analysis of the causes of cracks in reinforced concrete cast-in-place slabs The author, through his investigation and analysis of the cracks in reinforced concrete cast-in-place slabs he has been exposed to over the years, believes that they are mainly caused by the following factors: 1) shrinkage of concrete, 2) quality of concrete raw materials, 3) quality of construction, 4) role of load, 5) influence of equipment discipline, 6) uneven settlement of foundation, etc Sometimes, its cracks are often caused by several reasons. Next, the author makes a simple analysis on the reasons of these aspects one by one. 1. The shrinkage of concrete is well known. The reason for the shrinkage of concrete is mainly due to the hydration of cement in the early hardening stage, which forms a new cement crystal. This crystal compound is smaller than the volume of raw materials, thus causing the shrinkage of concrete volume, which is called condensation. In the late hardening stage, it is mainly caused by the evaporation of free water in the concrete Moreover, if the concrete is in an environment where the temperature difference changes greatly, its shrinkage will be more intensified. At present, taking the residential construction in our city as an example, most of the cracks in the reinforced concrete cast-in-situ slab are caused by the shrinkage of concrete As the concrete itself has condensation and drying shrinkage during the hardening process, and the temperature difference in our city is large, the highest temperature in summer can exceed 35OC, and the lowest temperature in winter can reach - 10oC (refer to relevant data), with a difference of 45oC, while the expansion coefficient of concrete is 10-5/0C, so the temperature difference strain of concrete can reach 400u after the alternation of summer and winter in a year ε Above, considering that the restraint coefficient of column and wall to cast-in-place slab is 0.25 -- -0.35, and the temperature difference strain of concrete structure is about 60 -- 110u ε, Therefore, the reinforced concrete cast-in-situ slab is easy to crack in this case. 2. The quality of concrete raw materials In residential construction, there are also cracks in some reinforced concrete cast-in-place slabs, which are caused by unqualified raw materials used to make cast-in-place slabs If the cement setting or expansion is abnormal, short and irregular cracks will be generated, which are mostly generated in the early stage of concrete hardening; If the aggregate contains too much mud, irregular network cracks will occur with the drying of concrete; Sometimes alkali aggregate reaction will also cause cracks 3. Construction defects In residential construction, a considerable part of the cast-in-place reinforced concrete slabs have cracks due to construction reasons, including the following aspects: the strength grade of the concrete does not meet the design requirements, the thickness of the cast-in-place slab is not enough, the reinforcement is not placed in place, and the amount of reinforcement is insufficient, which will cause the cast-in-place slab to deflect too much, resulting in cracks at the bending and tension; The newly poured concrete slab will also sink due to the support of the formwork, which will increase the deflection of the floor slab, and cracks will also appear after the removal of the formwork; Especially for balconies and awnings Cantilever components, such as overhanging eaves, often cause cracks because workers step down the negative moment reinforcement on the slab during concrete pouring, which makes the component unable to bear the negative moment, and even cause these components to break seriously. 4. In residential construction, there are also a few cracks in cast-in-place reinforced concrete slabs due to the load effect During the reinforcement calculation of cast-in-place slabs, designers usually determine the reinforcement amount only according to its bearing capacity, and often neglect the checking calculation of the deflection and crack width caused by the load borne by the slabs in the normal use stage, which leads to cracks. These cracks sometimes exceed the maximum allowable value of the specification, which should also be paid enough attention 5. The influence of equipment profession In residential construction, the cracks of reinforced concrete cast-in-situ slab are also partly caused by the influence of equipment profession. At present, in the design of buildings, the equipment profession, especially the electrical profession, mostly lights and cable TV The pipelines required for communication are directly laid in the cast-in-place slab, and sometimes there are as many as 7-8 pipelines concentrated in a certain cast-in-place slab, and the diameter of these pipelines is mostly 2-3CM, which will greatly weaken the thickness of the cast-in-place slab at this location, thus causing the cast-in-place slab to crack at this location 6. Uneven settlement of the foundation In residential construction, there are also quite a number of cracks in the cast-in-place reinforced concrete slabs, which are caused by the uneven settlement of the foundation. Taking our city as an example, about 80% of the construction sites in our city are soft soil sites, and the bedding structure is generally: the surface is 1 to 1.5 meters of clay, and the second layer is silt or muddy soil The thickness is 6 to 25 meters, and the clay layer with high bearing capacity is below it. Therefore, most of the residential buildings with more than four floors in our city use pile foundations, but a considerable number of residential buildings with less than four floors use extended foundations. Under this geological situation in our city, if this foundation form is adopted, it is quite difficult to ensure the settlement of relatively long strip buildings is uniform. Therefore, in this case, Sometimes, the uneven settlement of the foundation will cause the tension cracking of the building and the cracking of the cast-in-place reinforced concrete slab

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FOXBORO 0303440C脉冲输入通道模块

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