2016年1月6號(hào)
原文：Building types and designA building is closely bound up with people，for it provides with the necessary space to work and live in .As classified by their use ,buildings are mainly of two types :industrial buildings and civil buildings .industrial buildings are used by various factories or industrial production while civil buildings are those that are used by people for dwelling ,employment ,education and other social activities .Industrial buildings are factory buildings that are available for processing and manufacturing of various kinds, in such fields as the mining industry, the metallurgical industry, machine building, the chemical industry and the textile industry. Factory buildings can be classified into two type’s single-story ones and multi-story ones .the construction of industrial buildings is the same as that of civil buildings .however, industrial and civil buildings differ in the materials used and in the way they are used.Civil buildings are divided into two broad categories: residential buildings and public buildings .residential buildings should suit family life .each flat should consist of at least three necessary rooms : a living room ,a kitchen and a toilet .public buildings can be used in politics ,cultural activities ,administration work and other services ,such as schools, office buildings, parks ,hospitals ,shops ,stations ,theatres ,gymnasiums ,hotels ,exhibition halls ,bath pools ,and so on .all of them have different functions ,which in turn require different design types as well.Housing is the living quarters for human beings .the basic function of housing is to provide shelter from the elements ,but people today require much more that of their housing .a family moving into a new neighborhood will to know if the available housing meets its standards of safety ,health ,and comfort .a family will also ask how near the housing is to grain shops ,food markets ,schools ,stores ,the library ,a movie theater ,and the community center .In the mid-1960’s a most important value in housing was sufficient space both inside and out .a majority of families preferred single-family homes on about half an acre of land ,which would provide space for spare-time activities .in highly industrialized countries ,many families preferred to live as far out as possible from the center of a metropolitan area ,even if the wage earners had to travel some distance to their work .quite a large number of families preferred country housing to suburban housing because their chief aim was to get far away from noise ,crowding ,and confusion .the accessibility of public transportation had ceased to be a decisive factor in housing because most workers drove their cars to work .people we’re chiefly interested in the arrangement and size of rooms and the number of bedrooms .Before any of the building can begin, plans have to be drawn to show what the building will be like, the exact place in which it is to go and how everything is to be done.An important point in building design is the layout of rooms ,which should provide the greatest possible convenience in relation to the purposes for which they are intended .in a dwelling house ,the layout may be considered under three categories : “day”, “night” ,and “services” .attention must be paid to the provision of easy communication between these areas .the “day “rooms generally include a dining-room ,sitting-room and kitchen ,but other rooms ,such as a study ,may be added ,and there may be a hall .the living-room ,which is generally the largest ,often serves as a dining-room ,too ,or the kitchen may have a dining alcove .the “night “rooms consist of the bedrooms .the “services “comprise the kitchen ,bathrooms ,larder ,and water-closets .the kitchen and larder connect the services with the day rooms .It is also essential to consider the question of outlook from the various rooms ,and those most in use should preferably face south as possible .it is ,however ,often very difficult to meet the optimum requirements ,both on account of the surroundings and the location of the roads .in resolving these complex problems ,it is also necessary to follow the local town-planning regulations which are concerned with public amenities ,density of population ,height of buildings ,proportion of green space to dwellings ,building lines ,the general appearance of new properties in relation to the neighborhood ,and so on .There is little standardization in industrial buildings although such buildings still need to comply with local town-planning regulations .the modern trend is towards light ,airy factory buildings .generally of reinforced concrete or metal construction ,a factory can be given a “shed ”type ridge roof ,incorporating windows facing north so as to give evenly distributed natural lighting without sun-glare .Assessment of natural radioactivity levels and radiation hazards due to cement industry AbstractThe cement industry is considered as one of the basic industries that plays an important role in the national economy of developing countries. Activity concentrations of 226Ra, 232Th and 40K in Assist cement and other local cement types from different Egyptian factories has been measured by using γ-ray spectrometry. From the measured γ-ray spectra, specific activities were determined. The measured activity concentrations for these natural radionuclide were compared with the reported data for other countries. The average values obtained for 226Ra, 232Th and 40K activity concentration in different types of cement are lower than the corresponding global values reported in UNSCEAR publications. The manufacturing operation reduces the radiation hazard parameters. Cement does not pose a significant radiological hazard when used for construction of buildings.1. IntroductionThe need for cement is so great. That it considered a basic industry. Workers exposed to cement or its raw materials for a long time especially in mines and at manufacturing sites as well as people, that spend about 80% of their time inside offices and homes (Mullah et al., 1986; Parades et al., 1987) result in exposure to cement or its raw materials being necessary reality so we should know the radioactivity for cement and its raw material. There are many types of cements according to the chemical composition and hydraulic properties for each one. Portland cement is the most prevalent one. The contents of 226Ra, 232Th and 40K in raw and processed materials can vary considerably depending on their geological source and geochemical characteristics. Thus, the knowledge of radioactivity in these materials is important to estimate the radiological hazards on human health.The radiological impact from the natural radioactivity is due to radiation exposure of the body by gamma-rays and irradiation of lung tissues from inhalation of radon and its progeny (Papastefanou et al., 1988). From the natural risk point of view, it is necessary to know the dose limits of public exposure and to measure the natural environmental radiation level provided by ground, air, water, foods, building interiors, etc., to estimate human exposure to natural radiation sources (UNSCEAR, 1988). Low level gamma-ray spectrometry is suitable for both qualitative and quantitative determinations of gamma-ray-emitting nuclides in the environment (IAEA, 1989).The concentration of radio-elements in building materials and its components are important in assessing population exposures, as most individuals spend 80% of their time indoors. The average indoor absorbed dose rate in air from terrestrial sources of radioactivity is estimated to be 70 nay h?. Indoors elevated external dose rates may arise from high activities of radionuclide in building materials (Zikovsky and Kennedy, 1992). Great attention has been paid to determining radionuclide concentrations in building materials in many countries (Armani and That. 2001; Rizzo et al., 2001; Kumar et al., 2003; Tortoise et al., 2003). But information about the radioactivity of these materials in Egypt is limited. Knowledge of the occurrence and concentration of natural radioactivity in such important materials is essential for checking its quality in general and knowing its effect on the environment surrounding the cement producing factories in particular.Because of the global demand for cement as a building material, the present study aims to:(1) Assess natural radioactivity (226Ra, 232Th and 40K) in raw and final products used in the Assist cement factory and other local factories in Egypt.(2) Calculate the radiological parameters (radium equivalent activity Read, level index I γ r, external hazard index Hex and absorbed dose rate) which is related to the external γ-dose rate.The results of concentration levels and radiation equivalent activities are compared with similar studies carried out in other countries.2. Experimental technique2.1. Sampling and sample preparationFifty seven samples of raw materials and final products used in the Assist cement factories were collected for investigation. Twenty five samples of raw materials were taken from (Limestone, Clay, Slag, Iron oxide, gypsum) which are all the raw mate選自.投標(biāo)書代寫網(wǎng) yipai178.com rial used in cement industry, 20 samples of final products were taken from Assist cement (Portland, El-Mohandas, White, and Soleplate resistant cement (S.R.C)). For comparison with products from other factories, 8 samples were taken from the ordinary Portland cement from (Helena, Quean, El-kalmia, and Torah) and 4 samples were taken of white cement (Sinai and Helena). Each sample, about 1-kg in weight was washed in distilled water and dried in an oven at about 110 °C to ensure that moisture is completely removed; the samples were crushed, homogenized, and sieved through a 200 mesh, which is the optimum size to be enriched in heavy minerals. Weighted samples were placed in a polyethylene beaker, of 350-cm3 volume. The beakers were completely sealed for 4 weeks to reach secular equilibrium where the rate of decay of the radon daughters becomes equal to that of the parent. This step is necessary to ensure that radon gas is confined within the volume and the daughters will also remain in the sample.2.2. Instrumentation and calibrationActivity measurements were performed by gamma ray spectrometry, employing a 3″×3″scintillation detector. The hermetically sealed assembly with a Nay crystal is coupled to a PC-MCA (Canberra Accuses). Resolution 7.5% specified at the 662 kef peaks of 137Cs. To reduce gamma ray background a cylindrical lead shield (100 mm thick) with a fixed bottom and movable cover shielded the detector. The lead shield contained an inner concentric cylinder of copper (0.3 mm thick) to absorb lead X-rays. In order to determine the background distribution in the environment around the detector, an empty sealed beaker was counted in the same manner and in the same geometry as the samples. The measurement time of activity or background was 43 200 s. The background spectra were used to correct the net peak area of gamma rays of measured isotopes. A dedicated software program (Genie 2000 from Canberra) analyzed each measured γ-ray spectrum.3. ConclusionThe natural radionuclide 226Ra, 232Th and 40K were measured for raw materials and final products used in the Assist cement factory in Upper Egypt and compared with the results in other countries. The activity concentration of 40K is lower than all corresponding values in other countries. The activity concentration of 226Ra and 232Th for all measured samples of Portland cement are comparable with the corresponding values of other countries. The obtained results show that the averages of radiation hazard parameters for Assist cement factory are lower than the acceptable level 370 By kg?1 for radium equivalent Rae, 1 for level index I γ r, the external hazard index Hex ≤1 and 59 (nay h?1) for absorbed dose rate. The manufacturing operation reduces the radiation hazard parameters. So cement products do not pose a significant radiological hazard when used for building construction. The radioactivity in raw materials and final products of cement varies from one country to another and also within the same type of material from different locations. The results may be important from the point of view of selecting suitable materials for use in cement manufacture. It is important to point out that these values are not the representative values for the countries mentioned but for the regions from where the samples were collected.Priestesses ConcreteConcrete is strong in compression, but weak in tension its tensile strength varies from 8 to 14 percent of its compressive strength. Due to such a low tensile capacity, flexural cracks develop at early stages of loading. In order to reduce or prevent such cracks from developing, a concentric or eccentric force is imposed in the longitudinal direction of the structural element. This force prevents the cracks from developing by eliminating or considerably reducing the tensile stresses at the critical misspend and support sections at service load, thereby rising the bending, shear, and tensional capacities of the sections. The sections are then able to behave elastically, and almost the full capacity of the concrete in compression can be efficiently utilized across the entire depth of the concrete sections when all loads act on the structure.Such an imposed longitudinal force is called a prestressing force, i.e., a compressive force that priestesses the sections along the span of the structural element prior to the application of the transverse gravity dead and live loads or transient horizontal live loads. The types of prestressing force involved, together with its magnitude, are determined mainly on the basis of the type of system to be constructed and the span length and slenderness desired. Since the prestressing force is applied longitudinally along or parallel to the axis of the member, the prestressing principle involved is commonly known as linear prestressing .Tension caused by the load will first have to cancel the compression induced by the prestressing before it can crack the concrete. Figure 4.39a shows a reinforced concrete simple-span beam cracked under applied load. At a relative low load, the tensile stress in the concrete at the bottom of the beam will reach the tensile strength of the concrete, and cracks will form. Because no restraint is provided against upward extension of cracks, the beam will collapse.Figure 4.39b shows the same unloaded beams with prestressing forces applied by stressing high strength tendons. The force, applied with eccentricity relative to the concrete centric, will produce a longitudinal compressive stress distribution varying linearly from zero at the top surface to a maximum of concrete stress, =, at the bottom, where is the distance from the concrete centric to the bottom beam, and is the moment of the inertia of the cross-section, is the depth of the beam. An upward camber is then created.Figure 4.39c shows the priestesses beams after loads have been applied. The loads cause the beam to deflect down, creating tensile stresses in the bottom of the beam. The tension from the loading is compensated by compression induced by the prestressing. Tension is eliminated under the combination of the two and tension cracks are prevented. Also, construction materials (concrete and steel) are used more efficiently.Circular prestressing , used in liquid containment tanks , pipes , and pressure reactor vessels , essentially follows the same basic principles as does linear prestressing . The circumferential hoop . or “hugging” stress on the cylindrical or spherical structure , neutralizes the tensile stresses at the outer fibers of the curvilinear surface caused by the internal contained pressure .From the preceding discussion, it is plain that permanent stresses in the priestesses structural member are created before the full dead and live loads are applied in order to eliminate or considerably reduce the net tensile stresses caused by these loads. With reinforced concrete, it is assumed that the tensile strength of the concrete is negligible and disregarded. This is because the tensile forces resulting from the bending moments are resisted by the bond created in the reinforcement process. Cracking and deflection are therefore essentially irrecoverable in reinforced concrete once the member has reached its limit state at service load.The reinforcement in the reinforced concrete member does not exert any force of its own on the member, contrary to the action of prestressing steel. The steel required to produce the prestressing force in the priestesses member actively preloads the member, permitting a relatively high controlled recovery of cracking and deflection. Once the flexural tensile strength of the concrete is exceeded, the priestess’s member starts to act like a reinforced concrete element.Priestess’s members are shallower in depth than their reinforced concrete counterparts for the same span and loading conditions. In general, the depth of a priestess’s concrete member is usually about 65 to 80 percent of the depth of the equivalent reinforced concrete member. Hence, the priestess’s member requires less concrete, and about 20 to 35 percent of the amount of reinforcement. Unfortunately, this saving in material weight is balanced by the higher cost of the higher quality materials needed in prestressing . Also, regardless of the system used , prestressing operations themselves result in an added cost : formwork is more complex ,，since the geometry of priestesses sections is usually composed of flanged sections with thin webs .In spite of these additional costs, if a large enough number of precast units are manufactured, the difference between at least the initial costs of priestesses and reinforced concrete systems is usually not very large. And the indirect long-term savings are quite substantial, because less maintenance is needed, a longer working life is possible due to better quality control of the concrete, and lighter foundations are achieved due to the smaller cumulative weight of the superstructure.Once the bean span of reinforced concrete exceeds 70 to 90 feet (21.3 to 27.4 m), the dead weight of the beam becomes excessive, resulting in heavier members and, consequently, greater long-term deflection and cracking. Thus, for larger spaces, priestesses concrete becomes mandatory since arches are expensive to construct and do not perform as well due to the severe long-term shrinkage and creep they undergo. Very large spans such as segmental bridges or cable-stayed bridges can only be constructed through the use of prestressing .Priestesses concrete is not a new concept, dating back to 1872,when P.H. Jackson ,an engineer from California, patented a prestressing system that used a tie rod to construct beams or arches from individual block. After a long lapse of time during which little progress was made because of the unavailability of high-strength steel to overcome priestess losses, R.E. Dill of Alexandria, Nebraska, recognized the effect of the shrinkage and creep (transverse material flow) of concrete on the loss of priestess. He subsequently developed the idea that successive post-tensioning of unbounded rods would compensate for the time-dependent loss of stress in the rods due to the decrease in the length of the member because of creep and shrinkage. In the early 1920s, W. H .Hewitt of Minneapolis developed the principles of circular prestressing His hoop-stressing horizontal reinforcement around walls of concrete tanks through the use of turnbuckles to prevent cracking due to internal liquid pressure, thereby achieving water tightness. thereafter , prestressing of tanks and pipes developed at an accelerated pace in the United States, with thousands of tanks for water,liquid,and gas storage built and much mileage of priestesses pressure pipe laid in the two to three decades that followed.Linear prestressing continue to develop in Europe and in France, in particular through the ingenuity of Eugene Freyssinet .who proposed in 1923-28 methods to overcome priestess losses through the use of high-strength and high-ductility steels.In1940,he introduced the now well-known and well-accepted Freyssinet system.P.W. Abeles of England introduced and developed the concept of partial prestressing between the 1930s and 1960s . F. Leonard of Germany, V. Mikhail of Russia, and T.Y. Lin of the United States also contributed a great deal to the art and science of the design of priestess’s concrete .Lin's load-balancing method deserves particular mention in this regard, as it considerably simplified the design process, particularly in continuous structures. These twentieth-century developments have led to the extensive use of prestressing throughout the world, and in the United States in particular.Ordinarily, concrete of substantially higher compressive strength is used for priestess’s structures than for those constructed of ordinary reinforced concrete. There are several reasons for this:(1) High-strength concrete normally has a higher modulus of elasticity. This means a reduction in initial elastic strain under application of priestess force and a reduction in creep strain, which is approximately proportional to elastic strain. This results in a reduction in loss of priestess.(2) In post-tensioned construction, high bearing stresses result at the end of beams where the prestressing force is transferred from the tendons to the anchorage fittings, which bear directly against concrete. This problem can be met by increasing the size of the anchorage fitting or by increase the bearing capacity of the concrete by increasing its compressive strength. The latter is usually more economical.Today priestess’s concrete is used in building, underground structures, TV towers, floating storage and offshore structures, power stations, nuclear reactor vessels, and numerous types of bridge systems including segmental and cable-stayed bridges. They demonstrate the versatility of the prestressing concept and its all-encompassing application. The success in the development and construction of all these structures has been due in no small measures to the advances in the technology of materials, particularly prestressing steel, and the accumulated knowledge in estimating the short-and long-term losses in the prestressing forces.二,、譯文建筑類型和設(shè)計(jì)大樓與人民息息相關(guān)，因?yàn)樗峁┍匾目臻g,，工作和生活中。由于其使用的分類，建筑主要有兩種類型：工業(yè)建筑和民用建筑各工廠或工業(yè)生產(chǎn)中使用的工業(yè)大廈,，而那些居住，就業(yè),，教育和其他社會(huì)活動(dòng)的人使用的民用建筑,。工業(yè)樓宇廠房可用于加工和制造各類采礦業(yè)，冶金工業(yè),，機(jī)械制造,，化學(xué)工業(yè)和紡織工業(yè)等領(lǐng)域?？煞譃閮煞N類型的單層和多層的廠房,，民用建筑,，工業(yè)建筑是相同的。然而,，工業(yè)與民用建筑中使用的材料,，在使用它們的方式不同。民用建筑分為兩大類：住宅建筑和公共建筑,，住宅建筑應(yīng)滿足家庭生活應(yīng)包括至少有三個(gè)必要的房間：每個(gè)單位,。一個(gè)客廳，一個(gè)廚房和廁所,，公共建筑,，可以在政治文化活動(dòng)，管理工作和其他服務(wù),，如學(xué)校,，寫字樓，公園,，醫(yī)院,，商店，車站,，影劇院,，體育場(chǎng)館，賓館,，展覽館,，洗浴池，等等,，他們都有不同的功能,，這在需要以及不同的設(shè)計(jì)類型。房屋是人類居住,。房屋的基本功能是提供遮風(fēng)擋雨,，但今天人們需要更他們的住房，一個(gè)家庭遷入一個(gè)新的居民區(qū)知道,，如果現(xiàn)有住房符合其標(biāo)準(zhǔn)安全,，健康和舒適。附近的房屋是如何糧店,，糧食市場(chǎng),，學(xué)校，商店,，圖書館,，電影院，社區(qū)中心，家庭也會(huì)問,。在60年代中期最重要的住房?jī)r(jià)值足夠空間的內(nèi)部和外部,。多數(shù)首選的一半左右1英畝的土地，這將提供業(yè)余活動(dòng)空間單住宅的家庭,。在高度工業(yè)化的國(guó)家,，許多家庭寧愿住盡量盡可能從一個(gè)大都市區(qū)的中心，“打工仔”,，即使行駛一段距離,，他們的工作。不少家庭的首選國(guó)家住房郊區(qū)住房的大量的,，因?yàn)樗麄兊闹饕康氖沁h(yuǎn)離噪音,，擁擠，混亂,。無(wú)障礙公共交通已不再是決定性因素,，在住房，因?yàn)榇蠖鄶?shù)工人開著自己的車上班的人,。我們主要感興趣的安排和房間的大小和臥室數(shù)目,。在建筑設(shè)計(jì)中的一個(gè)重要的一點(diǎn)是，房間的布局,，應(yīng)提供有關(guān)它們目的,，最大可能的便利，在住宅,，布局可根據(jù)三類認(rèn)為：“天”,，也必須注意“和”服務(wù)“。支付提供這些地區(qū)之間容易溝通,。天的房間,，一般包括用餐室,，起居室和廚房,，但其他房間，如一項(xiàng)研究,，可能會(huì)補(bǔ)充說,，可能有一個(gè)大廳，客廳,，通常是最大的,，往往是作為一個(gè)餐廳，也或廚房,，可有一個(gè)用餐涼亭,。“夜”的房間，臥室組成。 “服務(wù)”,，包括廚房,，衛(wèi)生間，儲(chǔ)藏室,，廚房和儲(chǔ)藏室的水廁,。連接天與客房的服務(wù)。這也是必須考慮的前景問題,，從不同的房間,，和那些在使用中最應(yīng)該盡可能最好朝南。,，然而,，它往往很難達(dá)到最佳的要求，同時(shí)對(duì)環(huán)境的考慮和位置,，的道路,。在解決這些復(fù)雜的問題，它也必須遵循當(dāng)?shù)氐某鞘幸?guī)劃與公共設(shè)施,，人口密度,，建筑高度，綠地比例的住房,，建筑線,，一般的外觀有關(guān)的法規(guī)鄰里關(guān)系的新特性，依此類推,。標(biāo)準(zhǔn)化是在工業(yè)大廈內(nèi)的,，雖然這些建筑物仍然需要遵守當(dāng)?shù)氐某鞘幸?guī)劃法規(guī)，現(xiàn)代趨勢(shì)是朝著輕,，通風(fēng)的廠房,。一般的鋼筋混凝土或金屬建筑，工廠可以給出一個(gè)“棚”類型坡屋頂,，將朝北的窗口,，給均勻分布沒有自然采光，陽(yáng)光刺眼,。由于水泥行業(yè)的天然放射性水平和輻射危害的評(píng)估抽象,，被視為水泥行業(yè)的基礎(chǔ)產(chǎn)業(yè)，對(duì)發(fā)展中國(guó)家的國(guó)民經(jīng)濟(jì)中起著重要的作用之一,。 226Ra的活度濃度,，232Th和40K亞西烏特水泥和其他地方的水泥類型，從不同的埃及工廠已經(jīng)使用γ射線光譜測(cè)量,。從測(cè)得的γ射線譜,，具體活動(dòng)進(jìn)行了測(cè)定,。這些天然放射性核素的活度濃度與其他國(guó)家報(bào)告的數(shù)據(jù)進(jìn)行比較。獲得226Ra的,，232Th和40K的活度濃度的平均值,，在不同類型的水泥比報(bào)道科委出版物的全球相應(yīng)值低。生產(chǎn)操作減少輻射危害的參數(shù),。水泥不構(gòu)成重大建筑施工中使用時(shí)的輻射危害,。一、介紹對(duì)水泥的需求是如此巨大,。它認(rèn)為一個(gè)基本的行業(yè),。作業(yè)工人，尤其是在地雷和生產(chǎn)基地以及人們?cè)诤荛L(zhǎng)一段時(shí)間,，大約80％的時(shí)間花在辦公室和家庭內(nèi)（Mullah等人,，1986年。帕雷德斯等人,，1987年水泥或原料曝光水泥或它是必要的現(xiàn)實(shí),，所以我們應(yīng)該知道的水泥及其原料的放射性原料）的結(jié)果。根據(jù)化學(xué)成分和每一個(gè)水力特性,，有許多類型的水泥,。波特蘭水泥是最普遍的一種。中226Ra,，232Th和40K的原材料和加工的內(nèi)容可以有很大的不同取決于其地質(zhì)源和地球化學(xué)特征,。因此，在這些材料中的放射性知識(shí)是重要的,，估計(jì)對(duì)人體健康的放射性危害,。從天然放射性輻射影響，是由于身體接觸輻射伽瑪射線和肺組織的照射吸入氡及其子體,。從自然風(fēng)險(xiǎn)的角度來看,，它是必要了解公眾照射劑量限值和測(cè)量地面，空氣,，水,，食品，建筑內(nèi)飾等提供天然環(huán)境輻射水平,，估計(jì)人體暴露于自然輻射來源（科委,，1988年）。低級(jí)別的伽瑪射線熒光光譜儀是適用于環(huán)境中的伽瑪射線發(fā)射核素（IAEA,，1989）定性和定量測(cè)定。建材及其組件的無(wú)線電元素濃度在人口風(fēng)險(xiǎn)評(píng)估是重要的,，因?yàn)榇蠖鄶?shù)人花費(fèi)80％的時(shí)間是在室內(nèi),。平均室內(nèi)從地面的放射性源的空氣中吸收劑量估計(jì)70 NGY H,？1。室內(nèi)升高,，可能出現(xiàn)的外部劑量率從高建筑材料放射性核素（愛因斯坦和肯尼迪,，1992年）的活動(dòng)。已支付的高度重視,，以確定在許多國(guó)家建筑材料放射性核素濃度（Armani和Tanta,，2001;佐等，2001; Kumar等,。,，2003年。Tortoise等,，2003）,。但這些材料在埃及的放射性的信息是有限的。知識(shí)的發(fā)生與濃度等重要材料的天然放射性是一般檢查其質(zhì)量和對(duì)周圍環(huán)境,，特別是水泥生產(chǎn)工廠明知其效果的關(guān)鍵,。由于全球水泥作為建筑材料的需求，本研究的目的是：（1）評(píng)估在艾斯尤特水泥工廠和在埃及其他地方的工廠使用的原材料和最終產(chǎn)品的天然放射性（鐳,，釷和40K）,。（2）計(jì)算的放射性參數(shù)（鐳Read，水平指數(shù)Iγr,，外部危險(xiǎn)指數(shù)六角和吸收劑量率）,，這是關(guān)系到外部的γ劑量率。與其他國(guó)家進(jìn)行類似的研究,，濃度和輻射相當(dāng)于活動(dòng)的結(jié)果進(jìn)行了比較,。二、實(shí)驗(yàn)技術(shù)2.1,。取樣和樣品制備在艾斯尤特水泥工廠使用的原材料和最終產(chǎn)品的57個(gè)樣品進(jìn)行了調(diào)查收集的,。 25個(gè)樣品取自原材料（石灰石，粘土,，礦渣,，氧化鐵，石膏）,，這是在水泥行業(yè)中使用的所有原材料,，最終產(chǎn)品的樣品取自20艾斯尤特水泥（波特蘭，EL-Mohandas,，白,，耐硫酸鹽水泥（SRC）的）。與其他工廠的產(chǎn)品進(jìn)行比較,，8個(gè)樣品取自普通硅酸鹽水泥（赫勒萬(wàn)基納,，EL-kalmia,，托拉）和白水泥（西奈半島和赫勒萬(wàn)），4個(gè)樣本,。每個(gè)樣品重約1公斤,，蒸餾水洗滌和干燥烤箱約110攝氏度，以確保徹底清除水分,，對(duì)樣品進(jìn)行粉碎,，均質(zhì)，并通過200目,，這是最佳的篩分在重礦物富集的大小,。加權(quán)樣本被放置在聚乙烯燒杯中，體積350立方厘米,。完全密封的燒杯4周,，使氡氣子體衰變率和氡氣氣體相等。這一步是必要的,，以確保樣品中的氡氣和子體也將被局限在體積內(nèi),。2.2。儀器儀表和校準(zhǔn)活度測(cè)量進(jìn)行伽瑪射線光譜儀,，采用3“×3”閃爍探測(cè)器,。密封裝配用的N a I晶體耦合的PC-MCA（坎培拉）。分辨率7.5％,，在662 k e V峰的137Cs指定,。為了減少伽瑪射線背景圓柱底部固定和移動(dòng)蓋屏蔽探測(cè)器。鉛屏蔽含有銅的同心圓筒內(nèi)部,，X射線吸收鉛,。為了確定探測(cè)器周圍環(huán)境中的背景分布，一個(gè)空的密封燒杯計(jì)算以同樣的方式,，在相同的幾何形狀的樣品,。活動(dòng)或背景的測(cè)量時(shí)間為43 200秒,。背景光譜被用來糾正的凈峰面積測(cè)量同位素的γ射線,。一個(gè)專用的軟件程序（2000）從堪培拉精靈分析每個(gè)測(cè)量γ射線譜。三,、結(jié)論在上埃及的艾斯尤特水泥工廠使用,，并與其他國(guó)家的結(jié)果相比，原材料和最終產(chǎn)品的天然放射性核素鐳,，釷和40K測(cè)定,。 40K的活度濃度低于所有其他國(guó)家的相應(yīng)值。硅酸鹽水泥的所有測(cè)量樣品中226Ra和232Th的活度濃度與其他國(guó)家的相應(yīng)值相媲美,。所獲得的結(jié)果表明,，輻射危險(xiǎn)參數(shù)的平均值為艾斯尤特水泥廠的鐳當(dāng)量Read的,，1的水平的指數(shù)I γ r,，外部風(fēng)險(xiǎn)指數(shù)六角≤1和59（NGYĤ低于可接受水平的370貝克公斤1,？ 1）吸收劑量率。生產(chǎn)操作減少輻射危害的參數(shù),。因此,，水泥制品不構(gòu)成重大建筑施工中使用時(shí)的輻射危害。在水泥的原料和最終產(chǎn)品的放射性變化,，從一個(gè)國(guó)家到另一個(gè)內(nèi)同一類型的材料,，從不同的地點(diǎn)。從選擇合適的材料在水泥生產(chǎn)中使用的角度來看,，結(jié)果可能是重要的,。重要的是要指出，這些值不為上述國(guó)家,，但是從那里收集樣品的地區(qū)的代表值,。預(yù)應(yīng)力混凝土具體是在壓縮強(qiáng)勁，但在張力弱：其拉伸強(qiáng)度變化從8至14％,，其抗壓強(qiáng)度,。由于這種低抗拉能力，在裝貨的早期階段彎曲裂縫的發(fā)展,。為了減少或防止來自發(fā)展中國(guó)家如裂縫,，同心或偏心的力量施加在縱向方向的結(jié)構(gòu)元素。這股力量阻止裂縫的發(fā)展,，以消除或大大減少在關(guān)鍵的跨設(shè)備和支持服務(wù)負(fù)載部分拉應(yīng)力,，從而提高了部分彎曲，剪切,，扭轉(zhuǎn)能力,。的部分，能夠表現(xiàn)彈性,，幾乎滿負(fù)荷生產(chǎn)的混凝土在壓縮,，可以有效地利用各地的具體章節(jié)的整個(gè)深度時(shí)，所有負(fù)載結(jié)構(gòu)的行動(dòng),。這種強(qiáng)加的縱向力,，被稱為1預(yù)應(yīng)力，即,，壓縮力,，部分預(yù)應(yīng)力沿跨度的結(jié)構(gòu)型元素之前死和活荷載或暫態(tài)水平活荷載橫向重力的應(yīng)用。涉及的預(yù)應(yīng)力類型,，連同它的大小,，主要取決于系統(tǒng)建設(shè)跨度和所需的細(xì)長(zhǎng)型的基礎(chǔ)上,。由于縱向預(yù)應(yīng)力施加沿著或平行的成員軸，預(yù)應(yīng)力原則通常被稱為線性預(yù)應(yīng)力,。首先,，由負(fù)載引起的緊張局勢(shì)將不得不取消的預(yù)應(yīng)力，才可以破解的具體產(chǎn)生壓縮,。圖4.39a顯示簡(jiǎn)單跨度鋼筋混凝土梁施加載荷下破獲,。在一個(gè)相對(duì)低負(fù)荷時(shí)，在混凝土梁底部的拉應(yīng)力達(dá)到混凝土的抗拉強(qiáng)度,，會(huì)形成裂縫,。因?yàn)闆]有約束對(duì)裂縫向上延伸，光束就會(huì)崩潰,。相同卸載梁與預(yù)應(yīng)力強(qiáng)調(diào)高強(qiáng)度的肌腱作用力,。力，應(yīng)用到具體的質(zhì)心相對(duì)偏心,，會(huì)產(chǎn)生一個(gè)縱向壓應(yīng)力分布,，從零線性變化，在頂面最大的混凝土應(yīng)力,，=,，在底部，是從具體的質(zhì)心的距離在哪里底梁,，橫截面的慣性的時(shí)刻,，是梁的深度。然后創(chuàng)建一個(gè)向上的傾角,。應(yīng)用于預(yù)應(yīng)力梁后負(fù)荷,。負(fù)載引起的光束偏轉(zhuǎn)，創(chuàng)建拉伸應(yīng)力在梁的底部,。從裝載的緊張局勢(shì)是由壓縮引起的預(yù)應(yīng)力補(bǔ)償,。張力下兩個(gè)防止和張力裂縫的組合被淘汰。另外,，建筑材料（混凝土和鋼）更有效地利用,。預(yù)應(yīng)力圓形，液體containment坦克,，管道,，壓力反應(yīng)容器中，基本上遵循相同的基本原則,，如非線性預(yù)應(yīng)力,。環(huán)箍。或“擁抱”的圓柱形或球形結(jié)構(gòu)上的壓力,，中所載的內(nèi)部壓力所造成的曲線表面的外層纖維的拉伸應(yīng)力,。從前面的討論，這是平原之前創(chuàng)建完整的死和活荷載適用于以消除或大大減少這些負(fù)載造成的凈拉伸應(yīng)力,，預(yù)應(yīng)力結(jié)構(gòu)構(gòu)件的永久應(yīng)力,。鋼筋混凝土，混凝土的抗拉強(qiáng)度是微不足道的,，無(wú)視,。這是因?yàn)閺膹澗禺a(chǎn)生的拉力是在加固過程中創(chuàng)建的債券抵制,。開裂和撓度,，因此在鋼筋混凝土的成員基本上是無(wú)法挽回的，一旦在業(yè)務(wù)負(fù)荷已達(dá)到其極限狀態(tài),。在鋼筋混凝土構(gòu)件的加固,，不施加任何成員自身的力量，相反的行動(dòng)預(yù)應(yīng)力鋼,。所需的生產(chǎn)預(yù)應(yīng)力成員的預(yù)應(yīng)力鋼積極預(yù)裝的成員,，允許一個(gè)相對(duì)高的開裂和撓度的控制復(fù)蘇。一旦超過混凝土的彎曲拉伸強(qiáng)度,，預(yù)應(yīng)力成員開始像鋼筋混凝土元素,。預(yù)應(yīng)力成員在深度較淺的比相同跨度和荷載條件下的鋼筋混凝土同行。在一般情況下,，預(yù)應(yīng)力混凝土構(gòu)件的深度通常是等效的鋼筋混凝土構(gòu)件的深度約65至80％,。因此，需要較少的混凝土預(yù)應(yīng)力成員,，加固量的約20％到35％,。不幸的是，這種節(jié)能材料的重量是平衡的預(yù)應(yīng)力需要更高質(zhì)量的材料成本較高,。另外,，無(wú)論系統(tǒng)的使用，預(yù)應(yīng)力行動(dòng)本身在增加成本的結(jié)果：模板更為復(fù)雜,，因?yàn)轭A(yù)應(yīng)力部分的幾何形狀通常薄腹板法蘭部分組成,。盡管這些額外費(fèi)用，如果一個(gè)大型預(yù)制件的數(shù)量足夠制造的,，至少在預(yù)應(yīng)力鋼筋混凝土系統(tǒng)的初始成本之間的差異通常是非常大,。和間接的長(zhǎng)期儲(chǔ)蓄是相當(dāng)可觀的，因?yàn)樾枰^少的維護(hù),，更長(zhǎng)的工作壽命是可能的,，因?yàn)楦玫幕炷临|(zhì)量控制，并實(shí)現(xiàn)更輕的基礎(chǔ)，由于上層建筑的累計(jì)重量較小,。豆大跨度鋼筋混凝土一旦超過70至90英尺,，梁的自重成為過度，造成較重的成員,，因此,，更大的長(zhǎng)期撓度和打擊。因此,，較大跨度預(yù)應(yīng)力混凝土成為強(qiáng)制性的,，因?yàn)楣伴T是昂貴的建設(shè)和不執(zhí)行以及由于嚴(yán)重的長(zhǎng)期收縮和徐變，他們?nèi)缍螛蛄夯虼罂缍刃崩瓨蛑荒芡ㄟ^采用預(yù)應(yīng)力構(gòu)造,。預(yù)應(yīng)力混凝土是不是一個(gè)新概念,，可以追溯到1872年，當(dāng)PH值 杰克遜,，來自加利福尼亞州的一名工程師,，發(fā)明了一種預(yù)應(yīng)力系統(tǒng)，使用拉桿從單個(gè)塊構(gòu)造梁或拱,。經(jīng)過一段時(shí)間的流逝,，在這期間沒有取得什么進(jìn)展，為不能用高強(qiáng)度鋼板,，克服預(yù)應(yīng)力損失,，重新蒔蘿，內(nèi)布拉斯加州,，亞歷山德里亞公認(rèn)的收縮和徐變預(yù)應(yīng)力損失的混凝土材料（橫流）的影響,。隨后，他開發(fā)的想法,，連續(xù)后張無(wú)粘結(jié)棒在棒中的成員,，因?yàn)槿渥兒褪湛s長(zhǎng)度減少由于時(shí)間依賴的壓力損失補(bǔ)償。在20世紀(jì)20年代初,，明尼阿波利斯Whereat循環(huán)發(fā)展的原則預(yù)應(yīng)力強(qiáng)調(diào)圍繞橫向鋼筋混凝土水池的墻壁,，通過螺絲扣的使用，以防止開裂由于內(nèi)部液體壓力,，從而達(dá)到水密性,。此后，預(yù)應(yīng)力開發(fā)步伐的加快在美國(guó)的坦克和管道,，水,，液體的數(shù)千輛坦克，儲(chǔ)氣庫(kù)的建成和預(yù)應(yīng)力壓力管道鋪設(shè)在隨后的二,，三十年的里程,。線性預(yù)應(yīng)力繼續(xù)在歐洲和法國(guó)發(fā)展，特別是通過別出心裁的尤金的Freyssinet，提出在1923年至1928年的方法,，通過使用高強(qiáng)度和高延性steels.In1940克服預(yù)應(yīng)力損失,，他介紹了現(xiàn)在眾所周知和公認(rèn)的Freyssinet系統(tǒng)。P.W.英格蘭abeles引進(jìn)和開發(fā)部分預(yù)應(yīng)力概念20世紀(jì)30年代和60年代之間,。五米哈伊洛夫,，俄羅斯，德國(guó),，哈德和TY美國(guó)林也做出了很大貢獻(xiàn)預(yù)應(yīng)力混凝土設(shè)計(jì)的藝術(shù)和科學(xué),。林的負(fù)載均衡方法值得特別提及的是，在這方面,，因?yàn)樗蟠蠛?jiǎn)化,，特別是在連續(xù)結(jié)構(gòu)設(shè)計(jì)過程中，,。這些20世紀(jì)的發(fā)展,，導(dǎo)致在世界各地，特別是美國(guó)和預(yù)應(yīng)力的廣泛使用,。通常情況下，大幅度提高抗壓強(qiáng)度混凝土用于預(yù)應(yīng)力結(jié)構(gòu)比普通鋼筋混凝土建造的,。這有幾個(gè)原因：（1）高強(qiáng)度混凝土通常有較高的彈性模量,。這意味著應(yīng)用預(yù)應(yīng)力下的初始彈性應(yīng)變的降低和減少蠕變，這大約是成正比的彈性應(yīng)變,。預(yù)應(yīng)力損失減少的結(jié)果,。（2）在后張法施工，高承載強(qiáng)調(diào)在預(yù)應(yīng)力筋轉(zhuǎn)移到直接承擔(dān)對(duì)混凝土的錨固件,，其中梁的最終結(jié)果,。這個(gè)問題可以通過增加錨固件的大小或增加混凝土的承載能力，提高其抗壓強(qiáng)度符合,。后者通常是更經(jīng)濟(jì),。今日建筑用預(yù)應(yīng)力混凝土地下結(jié)構(gòu)，電視發(fā)射塔,，浮式儲(chǔ)油和海上建筑物,，電站，核反應(yīng)堆容器,，橋梁系統(tǒng)的種類繁多,，包括段和斜拉索橋。他們表現(xiàn)出預(yù)應(yīng)力概念及其包羅萬(wàn)象的應(yīng)用程序的通用性,。在所有這些結(jié)構(gòu)的發(fā)展和建設(shè)的成功,，是由于在材料技術(shù)的進(jìn)步不小的措施，特別是預(yù)應(yīng)力鋼，積累的知識(shí),，在估算預(yù)應(yīng)力部隊(duì)的短期和長(zhǎng)期虧損

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