铝塑复合板幕墙抗风压性能试验研究

为研究铝塑复合板幕墙在风压作用下的抗变形能力,对7组不同规格的铝塑复合板试件进行了抗风压试验研究,得到了铝塑复合板的风压-变形曲线,并将试验结果与规范JGJ133—2001的计算结果进行比较。结果表明:随着风压的增加,铝塑复合板的风压-变形曲线呈明显的非线性关系;现行行业规范中关于铝塑复合板挠度的计算值大于试验值,偏于保守;不同铝材牌号对铝塑复合板的抗风压性能影响不大,但是对其残余变形的影响较大。     

加筋散粒体材料力学性能的大型三轴试验研究

着重研究了风积砂、加筋风积砂、砂砾、加筋砂砾等几种散粒体材料的强度和变形性能,分析了加筋对材料强度和应力-应变关系的影响。研究表明：通过三轴试验可以获得散粒体材料的强度参数c和!;同时,可以拟定材料本构关系的各主要参数。     

碳纤维加固震损混凝土框架节点抗震性能的初步研究

首先对 4个十字形混凝土梁板柱节点进行破损加载 ,模拟中小地震中的损伤 ,然后进行灌缝修复和粘贴碳纤维加固。加固试件和对比试件的低周反复荷载试验结果表明 ,采用的加固修复方法非常有效 ,受损试件加固后的抗震性能要优于对比试件。     

Cyclic behaviour of post-Northridge WUF-B connections

The purpose of this study is to evaluate the cyclic behavior of post-Northridge Welded Unreinforced Flange-Bolted web (WUF-B) connections made using new notch tough welding materials and welding procedures, and a modified access hole. Since no WUF-B connection test results were found which satisfy the minimum design and detail requirements of the 2002 AISC Seismic Provisions for Structural Steel Buildings, this study made three full-scale test specimens of WUF-B connections according to the provisions. The main variable of the specimens was the ratio of the panel zone strength to the connected beam strength (panel zone strength ratio). Quasi-static cyclic testing was conducted. This study found that post-Northridge WUF-B connection specimens having a stronger panel zone experienced more significant slip between the bolted shear tab and the beam web. It was observed that the slip caused stress concentrations in and around the access hole, resulting in connection failure. The WUF-B connection specimen having the weakest panel zone did not, however, experience excessive slip between the bolted shear tab and beam web. Moreover, this WUF-B specimen could not achieve the required beam strength. This study observed that post-Northridge WUF-B connections with a panel zone strength ratio ranging from 0.9 to 1.6 provides a drift ratio exceeding 0.2. This drift ratio is required for satisfactory performance of the connections of Intermediate Moment Frames. Furthermore, this study proposed an analytical model for post Northridge WUF-B connections having different panel zone strength ratios.     

Short-term bacterial community composition dynamics in response to accumulation and breakdown of Microcystis blooms

Short-term bacterial community composition (BCC) dynamics in response to accumulation and breakdown of Microcystis blooms were examined by conducting in situ mesocosm experiments with varying levels of Microcystis sp. biomass, ranging from 15 to 3217 μg/L as measured by chlorophyll-a concentration in the freshwater water column. The BCC was assessed by means of terminal restriction fragment length polymorphism (T-RFLP) of 16S ribosomal RNA genes followed by cloning and sequencing of selected samples. The results showed that the composition of both free-living and particle-attached bacterial communities changed during the accumulation and breakdown phases of a Microcystis bloom, and differences were also evident with different levels of Microcystis biomass. The relative abundance of bacteria affiliated with Micrococcineae and Legionellales increased in general after amendment with Microcystis. Significant correlation between the relative abundance of Micrococcineae and breakdown of Microcystis biomass was also observed. Canonical correspondence analysis (CCA) showed that the changes in the free-living and particle-attached bacterial community were mostly related to the changes in the concentrations of chlorophyll-a, dissolved organic carbon (DOC), dissolved oxygen (DO) and pH, which were mainly induced by the breakdown of Microcystis biomass. Overall, our study revealed the following: i) accumulation of Microcystis blooms and their breakdown have strong impacts on bacterial community composition; ii) there might be saprophytic association between Micrococcineae and decomposition of Microcystis biomass; iii) it is necessary to reveal potential associations between Legionellales organisms and Microcystis blooms in eutrophic freshwater lakes.     

U形预应力预制构件叠合梁受弯性能试验研究

提出一种新型的叠合梁结构——U形预应力预制构件叠合梁，探讨了其结构特点。通过二根叠合梁及一根整浇梁的对比试验，研究分析了此种叠合梁的受力特点、破坏特征和受弯承载力，并提出正截面受弯承载力的设计建议，以促进其在我国的推广应用。     

Experimental study of structural fire behaviour of steel beam to concrete filled tubular column assemblies with different types of joints

This paper presents experimental results of structural fire behaviour of steel beam to concrete filled tubular (CFT) column assemblies using different types of joints. The joint types include fin plate, end plate, reverse channel and T-stub. The structural assembly was in the form of a “rugby goalpost”. In each test, loads were applied to the beam and then the structural assembly was exposed to the standard fire condition in a furnace while maintaining the applied loads. In total, 10 tests were carried out. In eight of the 10 tests, fire exposure continued until termination of the fire test, which was mainly caused by structural failure in the joints under tension when the beam was clearly in substantial catenary action. In the other two tests (one using fin plates and one using reverse channels), fire exposure stopped and forced cooling started when the beam was near a state of pure bending and just about to enter into catenary action. The results of the experiments indicate that even the relatively simple joints used in this study were able to allow the beams to develop substantial catenary action so that the final failure times and beam temperatures of the assemblies were much higher than those obtained by assuming the beams in pure bending. At termination of the tests, the beams reached very high deflections (about span/5), even then failure of the assemblies always occurred in the joints. Therefore, to enable the beams to reach their full potential in catenary action, the joints should be made to be much stronger. The results also indicate that reverse channel connection has the potential to be developed into a robust connection characterised by high stiffness, strength, rotational capacity and ductility. The beams in the two cooling tests developed high tension forces, however there was no structural failure in the assemblies. The principal aim of this paper is to present experimental results of joint behaviour in fire (which until now is lacking) to enable development of better understanding and rational design methods for robust construction of joints to resist extreme fire attack.     

Bending capacity of composite girders with Class 3 section

In this research, the flexural behaviour of composite girders under non-monotonic service loads and the bending capacity of composite girders with Class 3 section were studied through experimental work. Three specimens were fabricated and, through the 4-point flexural test, the stiffness and strength of the composite girder under hogging moments were observed. Test specimens were overhanging simple support beams, in total 6 m long. From the test results, the deflection, stiffness, moment-curvature relationship, and strain distribution of the composite girder section under service and ultimate loading were analyzed. The flexural behaviour under reloading-unloading cycles and tension stiffening effects on the mechanical behaviour of composite girders were discussed. The ultimate strength of composite girders with different Class flange sections and a same Class web section were also studied. Test results were analyzed by design equations in Eurocode 3 and 4 for flexural stiffness and sectional resistances. Also, a new simple design equation for the bending capacity of composite girders with Class 3 sections was suggested.     

Robustness of hollow clay masonry units and seismic behaviour of masonry walls

As the recent experimental investigations indicated, the robustness of masonry units is one among the most decisive parameters which define the behaviour of masonry walls when subjected to seismic loads. If local brittle failure of units occurs, the mechanism of behaviour and known relationships between the strength and ductility properties of masonry walls change. In such a case, the design values of load bearing and energy dissipation capacity of masonry walls are overestimated, although the equations and requirements specified in the codes have been taken into consideration. If brittle units are used for the construction of structural walls, the actual structure will be exposed to an increased level of seismic risk although it has been designed for earthquake loads according to codes. This is especially the case of reinforced masonry, where brittle local failure prevents the transfer of predicted forces from reinforcing steel to masonry units. In order to provide limitations for the use of hollow units with large hole volume ratio and thin shells and webs in seismic areas, a measure to define the qualitative term “sufficient robustness”, specified in Eurocode 8, should be found.