سال:1386 | دوره: | شماره: |تعداد مقالات:8

For load-bearing mineral wool insulations, compressive stress at 10% deformation is an important property which is studied as a function of density. The determination of compressive behavior of insulations is not a simple and fast test procedure. However, it can be estimated with indirect test method of determination of density which is simple and fast.For indirect test of σ10, it is necessary to find the relations of σ10 and ρ for estimation of mechanical behavior of mineral wool insulations without testing or testing them once in a while. Here, the wool structure, organic content, aging effects on compressive stress for glass wool, rock wool and slag wool are investigated.

The nonlinear response of a ten story steel structure with semi-rigid girder connections is studied under conditions of dynamic loading. The dynamic loading used in this study is the north-south component of the may 18, 1940 El Centro, California earthquake. To deal with the complexity of the problem the structure is idealized by a series of equivalent masses, lumped at the floor levels and restrained by weightless members. The physical model used to represent individual members consists of a flexible central beam with springs attached at both ends. All connections have the capability of exhibiting bilinear hysteresis curves.The analysis is accomplished within the general purpose computer program SAP 2000 V 10. Semi-rigid girder connections affect the properties of a structure in three ways: (a) by altering the relative girder to column stiffness, (b) by changing the strength or yield deformation characteristics, and (c) by decreasing the stiffness of the structure. The effects that these variables have on structural response are determined. The ground motion characteristics, intensity, and duration are also investigated.

Graph theoretical force methods are highly efficient for the generation of sparse and banded null bases and flexibility matrices, however, these methods require special considerations when the support conditions are indeterminate. These considerations with special methods are presented in this paper which leads to efficient utilization of graph theoretical force method for indeterminate support conditions with no substantial decrease in sparsity.

Traditional seismic design approach uses initially assessed natural periods as fixed design parameters for any structural system ignoring its dependency on original strength provided to meet elastic strength demand computed on the basis of such periods, divided by the response reduction factor. This implies the consideration of a constant stiffness obtained due to initial period while a varying yield displacement inversely proportional with response reduction factors. However, a series of recent studies shows that the reality being completely otherwise, the yield displacement of any structural system remains almost constant making assigned strength and hence, resulting stiffness both varying inversely with response reduction factor considered in the design. This reality puts a question mark on the validity of the existing approach. The present paper is a limited effort to resolve this issue. To achieve this end, the strength demand, inelastic displacement demand and ductility demand of a large category of systems encompassing all feasible combinations of lateral period and response reduction factors are computed through both the approaches and compared. While computing the inelastic response, elasto-plastic as well as various feasible degrading hysteresis behaviours, have been used. The study indicates that the traditional approach yields a safer estimation of the strength and ductility demand except for system with very stiff periods. On the other hand, inelastic displacement demand is underestimated by this traditional approach, which can be by and large compensated by multiplying this displacement demand by response reduction factor.

Systematic studies are reported for the service load behavior of continuous beams with precast decks. A hybrid procedure recently developed by the authors has been used for carrying out the studies. The procedure accounts for creep, shrinkage and progressive cracking of concrete of the decks. The age of concrete at the time of loading, magnitude of load, grade of concrete, relative humidity and tension stiffening are the parameters whose effects have been studied on the bending moments at the supports and midspan deflections.The relative humidity is found to be the more significant parameter affecting the timedependent changes, in bending moments at supports and midspan deflections.

The subject of pile foundation subjected to lateral cyclic load is an age-old problem confronted by Geotechnical Engineers. The environment prevalent in ocean necessitates the piles supporting offshore and onshore structures to be designed against lateral cyclic loading resulting from the effects of sea waves. Such loading induces remarkable deterioration in the interactive performance of the soil-pile system. This can be manifested as significant loss in pile capacity associated with increased pile head deflection. The work reported herein is aimed towards conducting extensive experimental investigation on model pipe pile in marine clay under lateral cyclic loading, subsequently followed by theoretical analysis using finite difference technique. The experimental results are compared with the theoretical results and reasonably good agreement is noted. This paper presents brief description of the experimentation and theoretical analysis carried out with some typical results and the relevant conclusions drawn therefrom.

Structures for covering large public spaces are more and more designed with innovative shapes involving combinations and/or modified forms of classical simple shapes such as plane, cylinder, sphere, ... etc. These innovative shapes are termed "freeform" and are created through the interaction between practical considerations for the structures and the artistic sense of the designers. Formex algebra and its programming language Formian can be of help in generating the geometry of freeform structures. In particular, there are two formex concepts that are of value in this context. These are the concepts of "pellevation" and "novation". The purpose of the present paper is to discuss the manner in which pellevation and novation can be used for freeform generation. In the paper, to begin with, the concepts of pellevation and novation are explained in terms of some simple examples. The process of freeform generation is then illustrated using a number of examples.

The primary purpose of building design is the creation of an indoor thermal environment, offering adequate living and working conditions for occupants. Thus, the objective is to consider local climatic conditions in the way of designing buildings for regions of the southern Algeria, where the hot and arid climate affects architecture and building materials.