Lightweight ribbed reinforced concrete sandwich panels in construction applications

        [Abstract] In this paper, the existing system of construction norms and the specific characteristics, to discuss the main production of prefabricated parts and system construction technology, focusing on in-situ two-way ribbed sandwich panel construction methods for the construction of such systems to provide reference.
        [Keywords:] ribbed sandwich construction construction
          
        A lightweight reinforced concrete structure
        1.1 light-steel structure system
        Light steel structures made from light steel frame, all kinds of light to make the external retaining wall structure, formed by the renovation and decoration of houses. Skeleton is the supporting body of lightweight steel construction with reinforced concrete frame structure, as bear the brunt of all the vertical loads, but also bear the load level and vibration. The supporting components mainly by the thickness of 1.5-5mm thin metal plates were cold-formed or cold-rolled steel and their products of thin-walled molding composition.
        Light steel building features are: light, precise, forming convenient, fast and suitable for mass production, transportation, construction and installation than those of convenience, can greatly shorten the construction period; can be large-scale use of non-professionals; but the construction of high precision, a large quantity of steel, cost is also high; exterior appearance, layout flexibility, light weight structures, seismic performance, in line with environmental protection and sustainable development requirements of China's domestic development of structural systems.
        1.2 Lightweight ribbed sandwich construction of reinforced concrete structural system
        Lightweight ribbed sandwich construction of reinforced concrete structural system of steel-reinforced concrete rib sandwich panel technology as the core, to the kinds of composite panels as the main load-bearing components (wall and floor). Its characteristics similar to the assembly-large panel building system, the difference is that an inner bay (outer) longitudinal walls and transverse walls are composed of several prefabricated parts, prefabricated wall panels of smaller sizes, wall panels to construct between the trabecular , column connections, forming a wall-frame system. Precast slab according to the actual situation can also be cast in place, each room not more than two.
        2 precast production
        2.1 The general requirements for materials
        (1) Production of sandwich panels of cement, sand, stone, steel quality and testing, preparation of concrete shall comply with the current national standard 'of concrete structural engineering construction and acceptance of standards' requirements;
        (2) The production of lightweight aggregate concrete wall, its concrete must be tested in line with the requirements of the relevant technical standards;
        (3) Production of panels used in isolated parts of the agent, the application isolation result is good, does not affect the quality of wall and floor decoration material;
        (4) the use of concrete early strength agent, water reducing agent and other additives should be tested in strict accordance with relevant provisions, in accordance with the need for trial.
        2.2 Sandwich Panel Production Process
        (1) install a good shape mold, laying a thick 5-15mm of concrete, leveling;
        (2) pre-production of a good light-weight thermal insulation material filled with evenly spaced according to the design block placed in the concrete floor above;
        (3) plant bulk solder good (or banding) of the steel skeleton placed in the vertical and horizontal to the multi-ribbed belt, and then coagulating the perfusion vertical and horizontal rib belt to the concrete;
        (4) and then shop in the above 5-15mm thick concrete and leveling. In order to ensure on the concrete under the ribs with a thin-walled and vertical and horizontal connectivity and compactness, in the shop, and when concrete is poured, the application vibrator vibrated dense, stripping to the age of conservation can be.
        The above-mentioned production process, such as shaking table in a large flat-panel production, quality and more reliable. Components prior to production, there must be a complete operational process design, which should include steel, insulation materials, pre-Li cases, insertion tendons, rings, set aside hole mold, such as laying pipes embedded electrical and fixed, the card set method, and equipped with the necessary set pieces of the fixed pieces and cards in order to ensure that the steel bars and buried in the component parts in the correct position, and not a result of watering concrete, vibrated, stripping to change location.
        Fixed parts, the card will be specially designed and manufactured parts, generally dark set bolts can be used, plastic card ring, insert, or other effective fixed fixtures.
        Brushing release agent before the pedestal surface or template surface must be clean, brushing release agent to be uniform, no leakage or accumulation of brush.
        3 sandwich panel building system construction
        3.1 General requirements
        (1) The crane shall be no obstruction within the scope of work, and stacking the appropriate number of elements should be the site of the venue for Transport should set the cis-ring road, road, space should be flat and have a solid and reliable drainage measures;
        (2) by the construction procedure of construction, the installation should work with water, electricity works in close coordination, organization interchange construction;
        (3) The installation of sandwich panel building construction and quality control and inspection shall, in addition comply with relevant provisions of this statute, there should be consistent with existing requirements;
        (4), construction safety, fire, etc., should be based on the characteristics of sandwich construction reference to relevant regulations.
        3.2 Transport and stacking
        (1) The method can be used or flat Yun Li Yun-France France. Load-bearing wall panels should adopt the legislative transportation method, non-load-bearing wall panels, precast slab can be used Ping Yun-law;
        (2) The roads are to be formed a solid, and there is sufficient width and turning radius. In transit should not be driving at high speed should be based on good and bad road speed control, starting, stopping to be steady. Handling and transport at night when the construction site should have adequate lighting facilities;
        (3) interpolation can be used stacked sandwich release method, by release method put peace in France. Load-bearing wall panels should be placed or inserted by release method, tools, special plug suitably placed frame by frame or place;
        (4) sandwich panel construction organization should be provided for the design of layout area, by type, model and stacked in the order lifting the work within a radius of hoisting machinery. Venue to be formed stacking compaction, and drainage facilities;
        (5) sandwich stacked, it can pave the way side wood, branch pad location should be determined depending on board type. By release of the wall to have a certain inclination, wall, between the lifting point location should be placed across wood. Amp wall plug, applications such as wooden wedges would be a fixed solid wall panels, and shelves may not sway frame to be placed a smooth interpolation release. Overlapping blocks stacked flat components according to component strength, the ground bearing capacity, strength and stacking skids, the stability of the determination; reposted elsewhere in the paper for free download http://eng.hi138.com

        (6) The location of components stacked piles should not prevent the observation axis control.

        3.3 Component Installation
        Installation method should be adopted by inter-closed Lifting Method. In order to install the error can be evenly shared, generally from the middle of the building unit or building one end of the second unit started lifting, in accordance with the order of the first interior wall after each and every closure. This method can be hoisting during construction to maintain the integrity of the building to facilitate the temporary fixed, closed the first as the standard rooms, as the basis for lifting the other wall.
        (1) sandwich panel construction flat-line copy
        The four corners of every house should be set standards for the axis control. Coordinates determined in accordance with the theodolite control of not less than two axes (vertical and horizontal direction of each one). On the floor of the control axis of theodolite must be directly upward from the bottom of the axis leads; every house of a standard level of points 1-2, in the first floor wall to determine control of horizontal lines. On each floor level of elevation from the control horizon are cited with the steel ruler measuring up; under the control and control of horizontal axis in turn release the vertical wall panels, horizontal lines and other line of position and elevation line; axis deviation pay-off should not exceed 2mm, pay-off event continuous bias should be considered from the building on both sides of the middle of an axis to adjust.
        (2) Erection
        Load-bearing wall panel installation should be preceded by-line test pendulum, not block board, may be appropriate to adjust the rib pillar width, windows and doors is not enough stack at block board, in-situ concrete wall thickness can be used instead;
        The temporary wall panels fixed to the wall with the scaffolding outside the bar and added some of the support;
        Wallboard in place, calibration work is based on wall panels on both sides of the wall edges and inner horizontal spacing (bay) as the basis. Bighorn four buildings must be from the bottom axis of theodolite calibration. When the wall panels at the bottom of the pop-up wall panels in place and pre-match both sides of the sideline immediately after checking with the vertical degree by foot, and then in order to determine foot pole spacing. Verticality of the adjustment method to solve the tightness of the provisional holder, wall to adjust the location of the error using crowbars toggle wall solution, each crane finished a unit, must be inspected once theodolite axis within the horizontal wall in order to guarantee that wall in place accuracy.
        As the components of production, actinomycetes, installation and so on all errors, so adjust the bias, they should care for people with flat walls and the main rooms and the main stairwell of neat. If a continuous bias, should be considered from the building on both sides of the middle axis to adjust in order to avoid error accumulation.
        (3) Sandwich Panel Installation
        Wallboard installation before leveling, and to ensure uniform wall sat dense plasma, when the local bedding thickness is greater than 30mm, it is desirable use of fine aggregate concrete leveling;
        Wallboard installed on each floor, it should be copied in the wall the top level bullet line, according to design requirements of reinforced concrete with poured pound line (circle) beams, and leveling, leveling error of less than 5mm;
        After the floor in place, adjust the height difference should be adopted when the jack leveling device;
        Wallboard in place, the correction, after fixed placement plate rib reinforced net, not less than C20 board watering ribs and construction of fine aggregate concrete columns can be used sticks or bamboo mini vibrator vibrating compaction.
        (4), structural column, wall rib strength of the concrete to meet the design request, or to take interim stabilization measures and reliable before it can carry out the construction of the upper component.
        (5), structural column, plate ribs on the conservation of coagulation at room temperature 12 hours under the concrete watering should be watered humid days, or to choose film aquasorb, closed in water retention;
        Wall panels, floor construction, the inspection should be carried out covert work and prepare inspection records;
        Non-load-bearing wall panels to install, with reference to light wall standard.
        Lightweight ribbed sandwich construction of reinforced concrete structural system with its many advantages will gradually play to their potential. Of course, the birth of a new structural system, but also over time the test, but also discover many new problems. But there is no doubt that with the continuous progress of science and technology and development, the structure of the system application and development prospects will be extremely broad.
          
        References:
        [1] Zhao Xian. Modern high-rise building structure design. Beijing: China Building Industry Press, 2000.
        [2] China's new building materials group compiled. New building materials construction manual. Beijing: China Building Industry Press, 2000.
        [3] Liu Song-Qing, stone water a long time, Wang Yuanqing and so on. Net framework of the system in the multi-light steel houses in applied research. Industrial buildings, 2002,32 (12).
        [4] Wang Zhuo, Xie Zhijie. On the block building development and characteristics. China Building Materials, 2002. Reposted elsewhere in the paper for free download http://eng.hi138.com

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