一、輕型鋼架結構形式在平改坡工程中坡屋頂多采用輕型鋼架，輕型鋼架的結構應具有結構外形及屋面坡度滿足使用功能要求，用鋼量省，承載力高，運輸、制作和現(xiàn)場安裝方便等特點。結合城市屋面平改坡的實際情況，給出以下四種結構形式。（1）兩端簡支輕鋼屋架采用兩端兩個較支座作為支撐點的支座連接形式，如圖 1 所示。這種形式的鋼屋架支座約束較少，屋架桿件的內(nèi)力較大，截面較大，用鋼量也較大。由于鋼筋混凝土圈梁僅在房屋外圈布置，所以新增坡屋頂與原結構之間的連接較弱屋面結構的整體剛度有所降低

　　1、 The lightweight steel frame structure is commonly used for sloping roofs in flat to sloping projects. The structure of the lightweight steel frame should have a structural shape and roof slope that meets the functional requirements, with low steel consumption, high bearing capacity, and convenient transportation, production, and on-site installation. Based on the actual situation of urban roof leveling and slope conversion, the following four structural forms are proposed. (1) The simply supported light steel roof truss at both ends adopts a support connection form with two opposite supports as support points, as shown in Figure 1. This form of steel roof truss has fewer constraints on the supports, and the internal forces of the truss members are larger, with a larger cross-section and a larger amount of steel used. Due to the fact that reinforced concrete ring beams are only arranged on the outer ring of the house, the connection between the newly added sloping roof and the original structure is weak, resulting in a decrease in the overall stiffness of the roof structure

　?。?）多點支撐輕鋼屋架是由左、右兩個三角形再分式小架現(xiàn)場組合而成的輕型鋼屋架，如圖 2 所示。這種結構形式的特點是:有利于運輸和現(xiàn)場吊裝。由于平改坡工程的施工現(xiàn)場一般比較狹窄，材料運送和吊裝都很不方便，鋼架采用這種結構形式可以解決上述施工中存在的問題。由于鋼架與新增圈(臥)梁可以設置多個支撐點，因此該屋架可以按多跨支撐架進行內(nèi)力分析。計算結果表明，該鋼屋架用鋼量明顯小于兩點支撐的鋼屋架。但由于鋼屋架的腹桿較多，坡屋面內(nèi)部可利用的空間較小。

　　(2) The multi-point supported light steel roof truss is a lightweight steel roof truss composed of left and right triangular sub frames assembled on site, as shown in Figure 2. The characteristic of this structural form is that it is conducive to transportation and on-site lifting. Due to the narrow construction site of the flat to sloping project, material transportation and lifting are often inconvenient. The use of this structural form for the steel frame can solve the problems encountered during the construction process. Due to the ability to set multiple support points for the steel frame and newly added ring (horizontal) beams, the roof truss can be analyzed for internal forces as a multi span support frame. The calculation results indicate that the amount of steel used in the steel roof truss is significantly less than that of the steel roof truss supported by two points. However, due to the large number of web members in the steel roof truss, the available space inside the sloping roof is relatively small.

　?。?）斜梁式立柱支撐輕型鋼架這種形式的屋面斜梁由 5~9 個圓形立柱支承，立柱間距為2.0m左右。圓形立與下部圈(臥)梁的預埋鋼板連接，如圖 3所示。該鋼架現(xiàn)場組裝簡便、靈活，承載力高，用鋼量省，構造比較簡單，非常適合在平改坡工程中應用。

　　(3) The inclined beam type column supports a lightweight steel frame. This type of roof inclined beam is supported by 5-9 circular columns, with a spacing of about 2.0m between the columns. The pre embedded steel plate connection between the circular vertical and lower ring (horizontal) beams is shown in Figure 3. The steel frame is easy and flexible to assemble on site, with high bearing capacity, low steel consumption, and relatively simple structure, making it very suitable for application in flat to slope engineering.

　?。?）三點支撐輕鋼架是由左、右兩個輕鋼架組合而成的三點支撐輕鋼析架結構形式，如圖4所示。鋼架與下部屋面梁之間設有三個支撐點，斜向架按兩端簡支進行受力分析，桿件受力較為合理。該架的特點是鋼架的構造形式較為簡單，坡屋頂內(nèi)部空間較大，可以在工廠提前制作，減少現(xiàn)場焊接。承載力較高，而且用鋼量較低，同時還可以適用于左右跨度不相等的特殊情況。二、混凝土屋面結構處理措施

　　(4) The three-point support light steel frame is a three-point support light steel truss structure composed of left and right light steel frames, as shown in Figure 4. There are three support points between the steel frame and the lower roof beam. The inclined frame is subjected to force analysis based on simple support at both ends, and the force on the members is relatively reasonable. The characteristic of this structure is that the steel frame has a relatively simple construction form, and the interior space of the sloping roof is relatively large, which can be pre fabricated in the factory to reduce on-site welding. The bearing capacity is high, and the amount of steel used is low. At the same time, it can also be applied to special situations where the left and right spans are not equal. 2、 Treatment measures for concrete roof structure

　　為增加新增坡屋面的整體剛度，保證輕型鋼架與原屋面結構牢固連接，需要在原有平屋頂承重墻上增設現(xiàn)澆鋼筋混凝土圈（臥）梁，對應輕型鋼架支座位置設置預埋件，在外圈增設混凝土檐口。新增加的鋼筋混凝土圈（臥）梁，通過植入原屋頂圈梁的鋼筋實現(xiàn)新、舊兩部分圈梁連接，植筋前需將原屋面防水層及保溫層局部鏟除，在施工完畢后需進行修復，露出原屋面結構，植筋后澆筑作為新增鋼屋架支座的鋼筋混凝土支墩或連系梁，并埋設支座預埋件。新增加的鋼筋混凝土圈（臥）梁與原有的縱橫承重墻的位置重合，當不能重合時需要設架空梁。

　　In order to increase the overall stiffness of the newly added sloping roof and ensure a firm connection between the lightweight steel frame and the original roof structure, it is necessary to add cast-in-place reinforced concrete ring (horizontal) beams on the load-bearing walls of the original flat roof, and set up embedded parts at the corresponding positions of the lightweight steel frame supports. Concrete eaves should be added to the outer ring. The newly added reinforced concrete ring (horizontal) beam is connected to the old and new parts of the ring beam by implanting steel bars into the original roof ring beam. Before planting the steel bars, the original roof waterproof layer and insulation layer need to be partially removed. After construction, they need to be repaired to expose the original roof structure. After planting the steel bars, reinforced concrete support piers or connecting beams are poured as new steel roof truss supports, and pre embedded parts for the supports are buried. The newly added reinforced concrete ring (horizontal) beam coincides with the original longitudinal and transverse load-bearing walls. When it cannot coincide, an overhead beam needs to be installed.

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