Structural steel and plane frame assemblies under fire action

By means of series of tests carried out on simply supported beams of standard rolled sections subjected to bending, fully analytically formulated calculation values were derived for the temperature-dependent stress-strain relationships of structural steel under fire action from normal temperature to 1000 °C.

Systematic series of investigations carried out on frame assemblies made up from rolled sections with high scale accuracy revealed the characteristic parameters influencing the critical temperatures. The analyses showed good-to-excellent agreement both for the temperature-displacement curves and for the critical temperatures, so that the integrity of the stress-strain relationships could also be verified for combined bending and compressive stress states and for stability-endangered assemblies.

The knowledge gained by the of experiment and computation furnished — in generalized terms — a basic concept for the simple and uniform assessment of the resistance to fire action of single elements and whole assemblies of structural steel subject mainly to bending stresses or endangered in stability. This allows the collapse temperatures of uniformly heated systems to be determined as a function of load utilization factor and system slenderness. These major parameters — load utilization factor and system slenderness ratio — are normal temperature design characteristics and can be determined using conventional methods.     

System reliability considerations in probabilistic risk assesment of nuclear power plants

The frequencies and consequences of severe accidents at nuclear power plants are examined using a systematic procedure called probabilistic risk assessment (PRA). These accidents may be initiated by equipment malfunctions, operator errors or external initiators such as earthquakes, floods and tornadoes. It is in the case of the external events that the structural system reliability concepts are utilized. Taking the seismic risk analysis as an example, this paper discusses the different elements of the analysis — hazard analysis, fragility evaluation, systems analysis and risk quantification — and examines how the structural system reliability methods are applied. Areas requiring further investigation by the PRA analysts are indicated and the data and research needs are identified.     

Problems with the Moscow office

When the new Office Building for the United States Embassy in Moscow was in the final construction stage, visible defects caused work on the building to be suspended; a detailed structural analysis was then carried out by the NBS Center for Building Technology. Its report highlights the problems that can arise both with a structural design — such as guarding against buckling and progressive collapse — and with the detailed execution of that design.     

Simultaneous determination of trace amounts of free cyanide and thiocyanate by a stopped-flow spectrophotometric method

Simultaneous determination of free cyanide and thiocyanate was investigated using a stopped-flow spectrophotometric method. 1,3-dimethylbarbituric acid/isonicotinic acid at pH 5.2 was used as the colour reagent for both cyanide and thiocyanate determinations. The absorption spectrum of the complex formed by cyanide and thiocyanate with the colour reagent has a maximum wavelength at 600 nm, giving a low detection limit of 0.5 μg l⁻¹ for cyanide and 1.5 μg l⁻¹ for thiocyanate. Two proposed processes — 1,3-dimethylbarbituric acid combined with formaldehyde masking cyanide and the ferric-thiocyanate methods — can simultaneously determine free and other simple forms of cyanide and thiocyanate existing at pH 5.2; comparison of results demonstrates that both approaches are in agreement. By taking into account the effect of temperature on colour development and by using the ratio of the regression slopes, one kind of standard solution (thiocyanate) can be used for both cyanide and thiocyanate calibration, thereby avoiding the need to use toxic cyanide standard solutions.     

The energy kernel system

This paper summarizes the deficiencies of the current generation of energy models. A new approach to model construction and maintenance is then described. This is based on the notion of an advanced machine environment — termed the Energy Kernel System (eks) — which employs an object-orientated architecture to manipulate methods and so create models according to templates supplied by a user. The elements of the eks, and the R. & D. planning now underway in Europe and North America, are described.     

Fire detector systems with ‘distributed intelligence’ the pulse polling system

Well over a million fire detectors are currently in use in the Federal Republic of Germany. Provided they are correctly installed and efficiently maintained, they detect fires reliably at a very early stage. At the present time, the false alarm rate equals about 1% of the number of installed detectors per annum. This false alarm rate must be at least proportionately reduced as further detectors are installed.

Since it is scarcely possible to improve tried-and-tested detector designs, the employment of higher-grade detector signal processing methods suggests itself.

However, ‘more intelligent’ detector signal processing using microprocessors calls for an entirely new fire detection system structure: detectors which independently ‘decide’ whether an alarm criterion is met and then initiate an alarm are replaced by sensors which continuously transmit their measured values to the ‘intelligence’ panel for evaluation. Passive panels which simply receive alarm signals from activated detectors and indicate these or transmit them to the fire brigade are replaced by active processors using permanently improved algorithms for the detection of real fires.

A structural change of this type is possible provided the positive — and the customary — characteristics of the conventional technique are not lost, viz. two-wire lines between detector and panel, simple installation and handling, easy detector replaceability, low cost, etc.

The pulse detector technology is described in detail; it combines the simplicity of conventional fire detection systems with new characteristics, e.g. identification of individual detectors, permanent functional check of all connected detectors, automatic notification of maintenance requirement prior to a slowly developing fault (e.g. such as that caused by corrosion or contamination), uniform response sensitivity unaffected by drifting from the operating points of the detectors and, above all, greater protection against false alarms.     

Advances in building energy simulation in North America

Recent advances in building energy simulation in North America are reviewed. Six innovative programs — HVACSIM⁺, GEMS, ENET, TARP, BESA, and BEVA — are described and important new simulation techniques in the areas of functional input, moisture absorption and desorption, interzone airflow, daylighting, and automatic optimization are discussed.     

Bolted joints in glulam and structural timber composites

The widespread adoption of the European design code for timber structures (EC5) will facilitate a number of design options previously unsupported by British Standards. This code uses design equations that need characteristic material data, which exists for solid timber and some sheet materials, but not for the structural timber composites that were evaluated in this research. In this programme high-tensile steel black bolts have been used with solid timber, glulam and two commercially available structural timber composites — Microlam™ and Parallam™. The results suggest that the timber composites offer similar performance to high-density timbers in line with EC5 design guidance.     

提篮式系杆拱桥施工全过程承载力分析

针对跨度为112m的京沪高速铁路九曲河特大桥提篮式系杆拱桥的5种施工方案，考虑结构的非线性和构件的极限承载能力，计人施工过程的变形和应力的叠加效应，用包含梁和索单元的空间组合结构模型，进行了大桥的结构行为分析，着重研究了各方案在施工全过程中的结构整体及构件的承载能力问题。     

Calculation of the displacements and Pacher''s rock pressure curve by the associative law for the fluidity-plastic flow

Expressions are derived for the radial displacements in the upper part of a cylindrical tunnel in a uniform isotropic massive that experiences constant radial pressure. The mathematical conclusions are reached using the associative law for the fluidity-plastic flow and four failure criteria: Mohr-Coulomb's linear criterion, Leon-Torre's parabolic criterion, and Hoek-Brown's new and old criteria. The displacements are determined under the condition that the load on the construction is equal to the rock pressure in the upper part, calculated by the joint Fenner-Talobre's and Caquot-Kérisel's approaches. Three computational examples are given — the metro-tunnel in Munich and the Channel Tunnel. The results obtained are compared with those measured in situ.     

Reviews

THE IMPROVEMENT OF LONDON'S GREEN BELT — A SECOND REPORT (SC 860R) Green Belt Working Group, Standing Conference on London and South East Regional Planning

THE SCHOOL OUTDOOR RESOURCE AREA School Council Project Environment 1970-73 (Longmans 1974: Price £2.95) University of Newcastle Upon Tyne Director — R W Coleton, Deputy Director — R F Morgan

URBAN WASTELAND A report on land lying dormant in cities, towns and villages in Britain by Timothy Cantell 1977 56pp. CIVIC TRUST.     

Technical publications: The design professionals' response

Summarized here are the results of a detailed study for the UK Building Research Establishment to discover how those involved in building design react to and use the technical publications of BRE and others. The results merit wider study; they reveal the types of publication preferred — and why — and also when and how technical publications are consulted. Also of wider interest are the comments elicited about BRE's output and how it could be improved.     

Buckling and postbuckling investigations of imperfect curved stringer-stiffened composite shells. Part B: Computational investigations

Computational investigations of the buckling and postbuckling behaviour of a stringer-stiffened composite wing torsion box employing the finite element method are presented. Perfect and imperfect configurations — considering geometrical imperfections as well as initial stresses - are discussed. Two different loadcases are investigated: pure axial loading and axial loading with a superimposed constant torsion moment. The buckling behaviour is determined by tracing the load-deflection curves using Riks' path following method. Additional investigations, such as accompanying eigenvalue analyses and first-ply failure calculations, are performed for the first loadcase. Special attention is put on the modelling of the stiffened regions, where eccentrically placed layers have to be taken into account due to the bonding of the stiffeners to the inner surface of the box. The results show interesting phenomena, such as additional buckling points in the postbuckling region, which, however, can hardly be detected by simply considering the load-axial displacement path.     

Structural reliability of concrete bridges including improved chloride-induced corrosion models

A structural deterioration reliability (probabilistic) model has been used herein to calculate probabilities of structural failure. New reinforced concrete corrosion initiation, corrosion rate and time-variant load models are proposed. Three durability design specifications are considered in a lifetime reliability analysis of a RC slab bridge. Time-variant increases in loads are considered also. It was found that the application of de-icing salts causes significant long-term deterioration and reduction in structural safety for poor durability design specifications. A reduced cover or increased water-cement ratio increases failure probabilities. When compared to the case of “no deterioration”, it was observed also that the probability of failure only marginally increased for good durability design specifications. The approaches described herein are relevant to other physical infrastructure also.     

The good, the bad and the peculiar: Cultures and policies of urban planning and development on the Gold Coast

As one of the fastest growing regions in Australia, the Gold Coast offers a profusion of competing values, perceptions and interests in the construction of its urban forms and identities. Amidst the profusion and confusion, there are signs that local government is attempting —however falteringly — to move beyond regional stereotypes towards a new paradigm for planning and imagining the Gold Coast.     

Interrupted interface on the cybernetics of digital design process

From the viewpoint of Batesonian cybernetics, ‘conscious purpose’ and ‘artistic process’ are distinct ends of a spectrum of the functioning of ‘self’. The conceptual stage of the design process is essentially an artistic activity unencumbered with accuracy, dimensionality, scale, program or even tectonics, albeit all of these maybe tacitly present at the ‘back of a designer's mind’. Artistic activities involve broad mental processes that are beneath the stratum of consciousness. By definition, consciousness is selective awareness; it is linear in execution and limited in its capability to synthesize complex parameters. One of the central questions of this paper is “if artistic process requires one to abandon, or relinquish conscious purpose at the time of the generation of the work of art, and if the early stages of artistic process is a result of a vast number of ‘unconscious’ forces and impulses, then how can the computer, which demands (and thus propagates) geometric precision, focused operation and rational execution, be part of that process?” This paper will explore how, cybernetically, the computer can be ‘coupled’ with ‘self’ (via a visual interface) and the artistic process. Three specially devised conceptual design exercises—namely BlurrDesign, BlinDesign and BlitzDesign—and three corresponding “interruptive” computer interface modifications were deployed in an introduction to digital media course. The results of this study are now under consideration for their effectiveness in promoting conceptual design using the computer, and how the ‘self’ might form a cybernetic whole with the machine. The findings could have implications in design pedagogy, informatics and interface design.     

国内外焊接残余应力的测试技术和理论分析的综述

本文对当前国内外焊接残余应力的测试方法和理论分析进行了简要综述,并结合工程特点,提出了作者的某些看法。     

An experimental investigation of the flow past hulls at leeway

When a ship is sailing, the hull moves obliquely through the water at a greater angle of leeway than when under power alone. A wind tunnel is used to investigate the flow past a Mariner type hull for the range of leeway angles expected when sailing. Flow visualisation experiments are conducted, and the non-wave-making components of hydrodynamic hull forces are measured.

The hull is a very low aspect ratio lifting body which develops (horizontal) lift to balance sail side force; it does this at the expense of considerable induced drag. The body is slender and fairly streamlined, but flow separation occurs at the bilges and shed vortex sheets roll up to form longitudinal vortices. These vortices, associated with much of the drag penalty, trail downstream near to the hull; they generally maintain their identities, at least for flow distances of the order of the ship's length. There is, however, some merging of vorticity between proximate vortices.

A systematic series of hull-like blocks is similarly tested to investigate the influence of certain parameters such as beam, draft and trim. The flow about these simplified hulls shows the same general features as that about realistic hulls. Specific conclusions for the block hulls indicate that the hydrodynamic repercussions on sailing ship performance of various changes are as follows — An increase in beam is marginally detrimental — An increase in draft is beneficial — Allowing the vessel to heel is beneficial — Trimming the vessel by the stern is beneficial.     

The structural safety of connections with fillet welds

The need to use unsophisticated probability-based approaches and methods in the structural safety analysis of welded connections and joints subjected to extreme loads and other actions is discussed. A limit state criterion of the fillet weld, its normal and shear stresses caused by permanent, sustained and extraordinary variable actions are considered. Stochastic processes and sequences of safety margins of welded connections are analysed. The analysis of instantaneous and time-dependent survival probabilities of welded connections is based on the concepts of conventional resistances and transformed conditional probabilities. The structural safety of beam-to-column connections is analysed and illustrated by a numerical example.