Asian journal of civil engineering
Volume:4 Issue: 2, October 2003

In this paper mechanical modelling of the dynamic load plate test with the Light Falling Weight Device (LFWD) is presented. The LFWD is employed on construction sites to verify the compaction degree of soil layers and to evaluate their bearing capacity. The mechanical models developed are intended to provide simple and efficient formulations, which allow a large number of numerical simulations at low expenses. The motion of the device is characterized by a massspring- dashpot system. Several one-dimensional linear and nonlinear representations of the soil are discussed and evaluated. Different phases of motion of the LFWD - soil interaction system are identified, and corresponding formulations of the equations of motion are given. In appendices efficient solution procedures of the governing equations of motion are proposed.

With the technology development on the compressive strength of concrete over the years, the use of high strength concrete has proved most popular in terms of economy, superior strength, stiffness and durability due to many advantages it could offer. However, strength and ductility are inversely proportional. High strength concrete is a brittle material causing failure to be quite sudden and ‘explosive’ under loads. It is also known that true axial compression of structural concrete columns (axially compressed) rarely occurs in practice. The stress concentrations caused by the eccentric loading further reduce the strength and ductility of high strength concrete. This paper presents results of testing eccentrically loaded columns externally wrapped with different types of materials. The experimental results show that external reinforcement can enhance the properties of high strength concrete columns.

In this paper, a procedure is developed which can be used to identify the natural frequencies and natural modes in vacuum of an Arch-Dam from forced vibration testing data of partially filled reservoir. The effect of hydrodynamic pressure is removed by using an efficient algorithm. To verify the procedure, a simple structure is substituted for the dam with known properties in vacuum. Then a thin SSSF-plate is considered as the retaining wall representing of the dam and a sub-structuring technique is used with regard to a three dimensional linear compressible inviscid fluid body. The calculated resonance in the illustrated example replaces the resonance which in practical in-situ has been measured. Also the effect of the wave absorption at the bottom andbank of the reservoir is considered. The hydrodynamic pressure of the reservoir is calculated using boundary element method. The results which derived by solving an inverse problem, are compared with the exact analytical responses of the plate.

In this article the genetic algorithm is employed to optimize scissor-link foldable structures. The advantage of using GA lies in the fact that the discrete spaces can be optimized without any complexity. Here displacement method is used for analysis with uniplet elements.

After some recent earthquakes that demonstrated the potential seismic vulnerability of some types of steel bridges, many transportation agencies have initiated programs to evaluate the seismic resistance of their existing bridges. However in some regions, the problem will be more severe by the fact that steel bridges have frequently been exposed, for years, to an aggressive corrosive environment, particularly where road de-icing salts have been heavily used, seismic-resistant members frequently appear to be severely corroded. Similar problems occur to other steel structures. To determine whether such rusted members can reliably exhibit stable ductile behavior that is expected during an earthquake, a number of rusted pieces (having up to a 60% loss of cross-sectional area) taken from an old steel bridge, were subjected to some tensionand cyclic bending tests. Non-cyclic tension stress-capacity and ductility did not change significantly due to corrosion. However, cyclic tests showed that, while stable hysteretic behavior comparable to that of unrusted specimen is possible, premature low-cycle fatigue, typically develops. Irregularities along the rusted surface apparently act as crack initiators and precipitate crack propagation throughout the section Keywords: corrosion, steel bridges, seismic resistance, cyclic bending, ductility, low-cycle fatigue, hysteretic energy

Based on worldwide practical experiences, a fully automated CAD/CAM system coveringthe process of design and fabrication for a complete spectrum of steel structures is presented in this paper. The system also supports cooperative planning for geographically distributed engineering offices and fabricators. A number of advantageous aspects of such system are also presented. It is believed that the limited capacity of the building industry in some developing countries is mainly due to its undeveloped planning process, including distributed design and detailing, as well as limitations in the fabrication procedures. Therefore, as the best solution, the paper proposes adaptation of a customised and localised version of this new technology. It is finally concluded that civil and structural engineers must particularly gear up to use such tools for a chance to make a successful transitional move to global markets and to make the local building industry strong enough for the challenges of the near future.

The paper presents a new quay wall design applied in the South Pars Port Project. The quay is constructed of 7 metre diameter circular caissons made of reinforced concrete ring elements stacked upon each other. The method was developed in order to avoid construction of a dry dock needed for casting of conventional caissons. The design conditions, design loads and the stability calculations are explained as well as the from the construction of the quay.

This paper describes current activities in the field of strong motion research in Iran. Theseismotectonics and seismological background is explained and current strong motionmonitoring in Iran is summarised. The Strong Ground Motion Network of Iran started itsactivities since 1973, and has recorded more than 4200 accelerograms. The highest ground acceleration recorded in this network was 1g at Zanjiran station in 1994 Zanjiran earthquake. At present the network consists of 986 digital and 71 analogue accelerograph. ISMN has been installed 92 accelerographs in 54 dams. The geophisical and geotechnical investigations for site geology have been conducted in 100 accelerograph stations.