隐藏式彩涂压型板屋面渗漏原因分析及解决方法

隐藏式压型板以其美观、抗渗漏、寿命长的优势被越来越多地用于建筑上。但是由于其横向搭接困难,故当建筑屋顶有天窗、风机、气楼等突起构造以及需要与采光带等不同材料组合时,容易产生渗漏。以隐藏式压型板的应用实例,论述其渗漏原因及解决方法。     

Test of screw fastened profiled roofing sheets subject to simulated wind uplift

Screw fastened light gauge steel profiled roofing sheets are predominantly subjected to wind suction, i.e., wind uplift, and may fail locally in the vicinity of screw fasteners under strong or sustained fluctuating wind uplift. A series of static tests was performed on three types of profiled roofing sheets to investigate their structural behaviour and profile effects under simulated wind uplift. The considered sheeting profiles were arc-tangent, trapezoidal and ribbed, and an alternate (or equivalent alternate) sheeting crest fastening system was adopted. It was found that structural behaviour of the roofing sheets under uplift loads was greatly dependent on the sheeting profiles including the shape and height of the crest. Both arc-tangent and trapezoidal type roofing sheets exhibited a large cross-sectional distortion stage and a deflection hardening stage, following a local plastic collapse in the vicinity of the screw fasteners at the central support. The ribbed roofing sheet, however, had a final failure mode of sudden fracture with cracks under the screw fastener head at the central support. The use of cyclone washers with screw fasteners reduced local plastic deformations and, in general, increased initial failure loads of the roofing sheets. Increasing the roofing span only slightly reduced the limit values of the reaction force per fastener at the central support due to the local failure characteristic of the screw fastened profiled roofing sheets.     

带滑动片固定座的压型钢板屋面对檩条的扭转约束

压型钢板与檩条采用固定座连接时,屋面板对檩条的扭转约束作用很大,所以不能忽略。通过ANSYS有限元建模,分析杭萧钢构生产的HXY-478压型屋面板与檩条采用固定座连接时,屋面板对檩条的扭转约束刚度,并提出相应的刚度计算公式。为验证有限元对固定座模拟的准确性,通过考虑次翘曲的约束扭转分析,为固定座的扭转刚度提供理论分析模型,并与有限元模型的计算结果进行比较,两者吻合很好。     

Komplexe Dachformen und ihre Anforderungen an die Unterkonstruktion

Complex roof shapes and the demands they place on the substructure. Over the past two decades the design requirements placed on the shapes of roofs made from roll‐formed aluminium profiled sheet have increased markedly, regardless of whether the sheet has a simple rectangular shape, is curved in a convex or concave manner and cut conically or is tapered or bulged out in a defined manner to produce elliptically or hyperbolically shaped sheets for building envelopes. Thanks to new roll‐forming technologies, it is now possible to produce profiled sheets that are no longer symmetrical with respect to their longitudinal axis and which can be tapered or bulged out, twisted in a planar manner about their broad flutes or curved. Two spectacular building projects completed in recent years clearly illustrate the enormous amount of effort needed for preparation and execution – from the planning of the supporting structure through to its installation and from the substructure and its measurement through to the actual covering of the roof – in order to design, manufacture and process such three‐dimensionally shaped profiled sheets to satisfy the demands made by clients and planners with respect to the aesthetics and function of the aluminium profiled sheets, and thus the building envelope.     

Wet concrete loading of profiled trough girders

Profiled trough girders act as the permanent formwork for reinforced concrete beams, and form a member known as a composite profiled beam. During the construction phase, the pouring of wet concrete may influence the strength and stiffness of the profiled girder. The method of profiled composite construction is thus described herein and the influence of the wet concrete loading of profiled trough girders is studied. A series of three profiled trough girders were tested under wet concrete loads, and their deformations were monitored. A folded plate finite element method is then developed to model the in-plane and out-of-plane deformations that the trough wall is subjected to during this wet concrete loading.     

自攻螺丝连接受力蒙皮体抗剪性能试验研究

受力蒙皮是考虑房屋屋面、墙面的压型钢板与框架、檩条进行可靠连接而共同工作的结构体系。本文对国内常用的V-840型压型钢板采用自攻螺丝连接的受力蒙皮体进行了抗剪试验研究,分析了不同间距自攻螺丝连接的受力蒙皮体的破坏形式及抗剪性能,并提出了不同间距布置的连接件对蒙皮体抗剪性能的影响,以及此类蒙皮体考虑蒙皮效应的条件。     

Schubsteifigkeit zweiseitig gelagerter Stahltrapezbleche

Shear stiffness of trapezoidal steel sheets with two edges fastened. Profiled sheeting is often fastened only at the two edges which are normal to the span of the profiles according to its uniaxial load bearing behaviour for transverse loading and due to high effort in achieving all‐sided fastening. According to available design codes it is not possible to use the shear stiffness of this kind of diaphragms to stabilise beams against lateral torsional buckling. Therefore the effect of unsupported edges parallel to the span is investigated numerically and experimentally. This nonlinear investigation includes the flexibility of the fasteners. The numerical results agree well with the test results up to failure load. A knock‐down‐factor depending upon the a/b‐ratio and the shear stiffness of the diaphragm supported along 4 edges is obtained from the parametric investigations. The application of this knock‐down‐factor to the shear stiffness of the diaphragm supported along 4 edges gives that for the diaphragm supported along 2 edges. All this applies for the design load according to [6]. The ultimate loads of the diaphragms are much higher than these design loads.     

预应力芳纶纤维布加固混凝土梁抗弯性能试验及理论分析

预应力技术是充分发挥FRP复合材料高强性能的一条有效途径。通过对预应力芳纶纤维布加固混凝土梁抗弯的试验,对预应力水平对梁抗弯承载力、刚度、延性的影响进行分析。结果表明:预应力水平为55%~65%时,预应力芳纶纤维布加固梁的开裂、屈服、极限荷载比非预应力芳纶纤维布加固梁分别提高约147%~165%、28%~50%、13%~31%,表明预应力芳纶纤维布能显著地提高混凝土梁的抗弯性能。承载力极限状态时,预应力梁为纤维布的断裂破坏,非预应力梁发生布与混凝土间局部脱粘破坏。在试验研究的基础上,采用弹塑性截面分析法计算梁的承载力,理论计算值与试验值吻合良好。     

恒大山水城酒店圆桌会议厅钢屋架结构设计

本文较详细地介绍了某酒店圆桌会议厅钢屋盖结构的设计过程,该屋盖由4种不同型号的Q345B焊接工字形钢梁和压型钢板组成,保证了整个结构的强度、刚度和稳定性。文中应用MIDAS软件对空间模型进行整体计算,并运用ANSYS软件对梁柱复杂节点进行有限元数值模拟,相关设计方法可供同类工程参考。     

碳纤维布抗震加固开门窗洞口砌体墙片的试验研究与受剪承载力分析

通过对6片开门窗洞口砖砌体墙片在低周往复荷载作用下的抗震性能试验研究,探讨碳纤维布用于抗震加固无筋开洞口墙片的破坏形态、受力特性和加固效果,对比不同碳纤维布粘贴方式对无筋开洞口砌体墙片抗震加固效果的影响,据此建议对地震区开窗洞墙体采用沿洞口周围粘贴碳纤维布并在窗洞角部附加锚固碳纤维布条的有效加固方式,对开门洞墙体采用沿洞口周围粘贴碳纤维布并在宽墙肢上对角粘贴碳纤维布的有效加固方式。同时根据试验研究结果,建立以碳纤维布拉杆机制为基础的碳纤维布加固开洞口砌体墙片的受剪承载力计算模型,计算结果与试验结果吻合较好,说明该计算模型能较好地反映碳纤维布与无筋砌体墙体共同工作的受力机理,可供工程设计参考使用。     

Sandwich‐Dachbauteile für Flachdächer

Sandwich panels for roof covering. Sandwich panels for roof covering, which are currently used, are in principle always equipped with a trapezoidal profiled face. It is because of this geometry that the longitudinal joints of the panels are easy made by overlapping the external metal faces. The bending stiffness of these profiled faces also largely avoid the increasing in deflection caused by creep effects of the core as a result of long‐time loading from snow and self weight. In particular for flat roofs of industrial buildings there are some disadvantages caused by the profiling of the outer faces, e. g. the sealing of openings in the roof. Furthermore the mounting of the profiled panels always have to be realized in the direction of apex to cullis because of the rain water flow conditions. This requirement premises a substructure with purlins. In the described research project sandwich panels with flat faces were developed, where penetrations can be sealed in an easy way and mounting of the panels perpendicular to the roof pitch, from frame to frame (without purlins) is possible. All necessary research was conducted, in particular with regards to creeping effects, sealing of the panel joint and special fixings. On the base of the obtained research results, practice oriented solutions are proposed.     

Beeinflusst die Kornsteifigkeit der Gesteinskörnung im Beton den Degradationsprozess infolge zyklischer Druckbeanspruchung?

Does the Stiffness of Aggregate in Concrete Influence the Degradation‐Process Due to Cyclic Compression Loads? Structures like bridges, cooling and wind towers etc. are not only exposed to environmental influences and constant static loads but also often to cyclic loads. Due to the latter, very fine microcracks can occur due to load cycles leading to a degradation in the microstructure of concrete and to a reduction of stiffness and strength. Up to now it is still uncertain, if and to what extent different aggregates and therefore different aggregate stiffnesses influence this degradation‐process and which consequences may result for the stiffness of concrete. Within the scope of the Collaborative Research Center 398 (SFB 398), lifetime‐oriented design concepts with the aspects of damage and deterioration were developed. In one of the subprojects (A13), the degradation of material properties due to cyclic loading was experimentally investigated. This paper gives an account of the investigations on concrete with different aggregate characteristics under cyclic compressive loading. Thereby aggregates with significant different characteristics (sandstone, basalt, quartzite) were selectively included with furthermore constant concrete composition. Specimens of these concretes were subjected to single stage cyclic loads with lower and upper stresses being constant during the whole test series. During the cyclic loading, the changes in the strains and the stiffness (Young's modulus) of concrete caused by the proceeding degradation in the microstructure were determined. Microscopic analyses at different numbers of cycles were done as well. The results of the investigations showed that the ratio between the stiffness of the coarse aggregates and the hardened cement paste significantly influences the degradation‐process. At the concretes with sandstone the lower stiffness of aggregates led to a comparatively lower reduction in concrete's stiffness and to a increase of microcracks in the concrete's microstructure after defined load cycles in comparison to concretes with quartzite or basalt.     

Web crippling behaviour of laterally restrained cold-formed steel re-entrant profiled deckings

Web crippling failure is often found to be critical in cold-formed steel profiled deckings during construction of composite slabs. Therefore, accurate prediction to the web crippling resistances of profiled deckings over internal supports under hogging moment is highly desirable. This paper presents an extensive experimental investigation into the structural behaviour of laterally restrained re-entrant profiled deckings under concentrated loads. A total of 104 web crippling tests on fully supported re-entrant profiled deckings with nominal yield strengths at 235 and 550 N/mm² are carried out to provide data for direct comparison with design resistances obtained from codified design rules. It should be noted that in the past, little attention has been paid to establish the lateral restraint condition of profiled deckings under concentrated loads in tests. Hence, local section distortion or ‘section spreading’ is often observed in tests but seldom dealt with rigorously during design development. In the present study, effective lateral restraints are provided to the test specimens in order to fully mobilize the web crippling resistances of the profiled deckings. It is found that the measured web crippling resistances are typically 20%–40% higher than those obtained from the codified design rules given in BS5950: Part 6, Eurocode 3: Part 1.3 and the North America Specification, depending on the steel grades and thicknesses, the load bearing lengths as well as the loading conditions.

In general, both BS5950 and Eurocode 3 give conservative web crippling resistances for re-entrant profiled deckings with both low and high strength steel under internal and end loading conditions. Moreover, the corresponding resistance factors determined according to a codified reliability analysis are considerably larger than the required values. Thus, the design rules are reliable and conservative, although they tend to be very conservative for profiled deckings under end loading condition. However, an examination on the design rules given in the NAS shows that only some of them are applicable to predict the web crippling resistances of low and high strength steel re-entrant profiled steel deckings. The design rule for IOF condition always gives both conservative and reliable resistances for both low and high strength steel profiled deckings, compared to the measured values. The design rule for EOF condition is also found to be both conservative and reliable for low strength steel profiled deckings only, but not for high strength steel profiled deckings. The design rules for ITF and ETF conditions are not applicable for both low and high strength steel profiled deckings according to the reliability analyses.

It is demonstrated that a set of new design rules specifically for re-entrant profiled deckings is needed for both improved efficiency and reliability. Moreover, the comprehensive set of test data is readily adopted to calibrate both finite element models and design expressions in subsequent studies.     

波形沥青防水板在坡瓦屋面中的应用

波形沥青防水板作为下覆层在坡瓦屋面中应用,除具防水功能外,同时还能通风、除湿、隔热。本文指出波形沥青防水板在国外可与任一种硬质瓦配合使用,已广泛应用;在国内目前尚无相应的产品技术标准,其抗荷载能力的实验标准与方法亦需完善;实际采用时,应注意产品性能受其生产工艺的影响。     

Buckling analysis of thin-walled sections under general loading conditions

This paper presents an investigation of the buckling behaviour of thin-walled sections subjected to general loading conditions. The semi-analytical finite strip method is used. The existing results are only for sections subjected to a uniform loading, namely: uniform compression, uniform bending and uniform distributed loads, which are applied at the shear centre. For a general loading condition, we proposed the realizing linear analysis first to give longitudinal stresses. The stiffness matrix is provided in the standard manner. Each strip is divided into cells and longitudinal stresses are recorded in these cells. The integrations are performed on each cell domain and the sum of them provides the geometric matrix of the strip.     

金属屋面种植工程技术探讨

金属屋面种植工程要考虑新增恒载和活荷载的允许范围,各构造层次(由下而上)为压型钢板基层、隔汽层、保温层、防水及耐根穿刺层、排蓄水层、植被层,宜选用自重轻、使用寿命长的材料;施工时要考虑女儿墙、落水口、出屋面构件等节点处的防水措施和建成后的屋面养护。此类工程的成功,已为实践所证实。     

沉积软岩强度和变形特征的研究综述

The strength and deformation characteristics of sedimentary soft rock evaluated in relation to several large-scale researc and construction projects in Japan are reviewed.The elastic stiffiness at small non-linearity due to strain and pressure level,and viscous properties are described.The elastic stiffness from triaxial tests using high-quality core samples while measuring stresses and strains accurately is basically the same as the corresponding value from field shear wave velocity.It is necessary to take into account the dependency or stiffness on shear and pressure level,which could be evaluated by relevant laboratory stress-strain tests while referring to results trom relevant field loading tests.Loading rate effects due to the material viscous properties could be simulated by a non-linear three-component model.     

冷弯薄壁型钢檩条两种稳定计算模式的比较

讨论国家规范GB50018-2002《冷弯薄壁型钢结构技术规范》“和欧盟规范EC3-1-3对冷弯薄壁型钢檩条承载能力的两种计算模式的差异：拉条和屋面板对檩条抗扭约束刚度及其整体稳定的重要影响,进行檩条畸变屈曲和翘曲应力的计算,评估工程实践中可滑动的卷边咬合式屋面板对檩条的抗扭约束刚度以及拉条的构造等对檩条的工况作用问题。对工程实践具有重要参考价值。     

网架屋面隔声吊顶做法及施工技术

某影院屋面工程采用网架结构支撑压型板形式,空腔层隔声吊顶采用8层12mm厚纸面石膏板及2层玻璃棉板,中间形成650mm空腔层,空腔层上、中、下有设备管道穿插,施工交叉多,工艺复杂,施工难度较大。通过施工设计方案可行性分析,打破常规,采用一种类似串糖葫芦吊点的做法,即在网架下弦转换层增加槽钢,并改进各吊点细部做法,解决了隔声层施工技术难题。     

Cold-forming effect on stainless steel sections

Stainless steel exhibits greater extent of strain hardening than carbon steel, which leads to significant change in mechanical properties (increase in yield strength and decrease in ductility) of the stainless steel material due to the cold forming process. These changes of the mechanical properties depend mainly on the magnitude of residual stresses and equivalent plastic strain induced by the cold working. This paper presents an analytical model for determining the residual stresses and the corresponding plastic strain by means of Maple software simulating the cold forming process. The analytical model in Maple is validated by the previous numerical and experimental data of cold formed sheets. The increased material properties are determined after cold forming for corners and flat faces of sections considering the residual stresses and plastic strain and validated with the previous test results. For the prediction of the increased yield strength, new material properties with respect to the induced plastic strain based on tests are set for cold bending process in the analytical model. The analysis for the increased yield strength is calculated for four stainless steel grades, i.e., austenitic (1.4404), ferritic (1.4003), lean-duplex (1.4162) and duplex (1.4462) and the results are compared with the previous predictive models of the strength increase.