Applied Mechanics and Materials Vol. 147

Abstract: This paper analyzed natural vibration frequencies and vibration modes of suspend-dome structure with finite element method. Firstly, to get the corresponding vibration mode of each frequency of the structure, understand the distribution of directional stiffness in the structure, and realize the basic natural vibration characteristics, this paper analyzed the natural vibration characteristics of suspend-dome structure. And then, this paper analyzed such four parameters as rise, roofing mass, sectional stiffness of the rods, and prestress in the cables. Through comparison of the four parameters, we can get the similarities and differences among their frequencies and vibration modes, and whether or not the mass and the stiffness are harmonious, and draw some valuable conclusions for structural design.

Abstract: Past earthquake damages to road and highway structures such as bridges and tunnels demonstrate that it can severely disrupt network performance. These types of lifeline damages negatively impact the economy of the region, as well as post-earthquake emergency response and recovery. The seismic performance of these structures is almost difficult to model, because performance is a function of design, age, and local geotechnical conditions. In addition, earthquake intensity is also highly uncertain. Since the vulnerability of transportation network is not a rapidly quantifiable concept, and road networks are vulnerable to many events, many of researchers tried to find acceptable definitions in this regard. This pilot study presents a Seismic Vulnerability Score Assignment Model (SVSA) applying linear regression technique for two types of road structures; namely bridges and tunnels as samples. This model helps the project managers and decision makers rank the road structures based on seismic vulnerability scores easily.

Abstract: The width of effective slab to estimate the beam flexural strength at the beam ends in structures subjected to lateral loading, such as earthquake, is not explicitly addressed in design codes. As a result, designers often ignore the contribution of floor slabs to the lateral load resistance. There is a need for a simple model to assess the slab contribution to beam strength for analysis and design. General expressions for the yield loading and stiffness characteristic of the slab element have been developed which is more sensitively depend on yield line theory beside other parameters such as spacing, yield strength, area of reinforcement, and the span length. A model considering beam growth, bending effects and the slab effect is being considered in the present work. The results of the analytical investigation are compared with experimental results. The slab element model is then used to conduct a parametric study aiming to investigate the effect of the distribution and strength of the slab steel. It is shown that the performance of the unit is directly related to this steel.

Abstract: The inelastic seismic response of an existing multi-span concrete bridge is investigated by performing nonlinear static pushover analysis. The bridge is subjected to lateral forces distributed proportionally over the span of the bridge in accordance with the product of mass and mode shape. The bridge is pushed up to the target displacement and the hinge formations of the bridge in different steps of the pushover procedure in the transverse direction are obtained. The expected capacity of the bridge is evaluated and compared with the displacement demand.

Abstract: To protect downstream of hydraulic structures against erosion and degradation, must dipress water energy. one of the most comon methods to achive this purpose is constructing the stilling basin at the downstream of such structures. In stilling basin, the water energy dissipated by taking place of hydraulic jump. When a hydraulic jump occurs, the hydrodynamic and hydrostatic forces effect on the stilling basin floor slab. These forces include the force due to water weight and the up lift force affected the slab below which these forces are classified in hydrostatic. also the other force is hydrodynamic force due to pressure fluctions below the hydraulic jump. To keep the stilling basin stabillity from liffting up and destruction must the resistant forces be equal to destroyer forces. In this study after discution about the hydraulic jump and its resultant forces, a equation has been offerd to determine the thickness of stilling basin floor slab using buckingham theory andsoftware DATAFIT. Finaly the slab which evaluated by physical model, simulated using mathematical model(software ANSYS 10) and studied. The stress and strain diagrams were extracted. Results showed that physical and mathematical models were matched very good.

Abstract: National effort to recycle construction waste as structural concrete usage of high economic value is ongoing, but performance rate of recycling is a low-level due to a lack of awareness on the recycled aggregates. Accordingly, the goal of this study was to verify the structural applicability of recycled aggregates. This study compared a compressive strength based on the replacement ratio of natural aggregate and recycled aggregate, and analyzed a correlation of wave velocity due to the increase in compressive strength under the same condition. The 『design standard strength – replacement ratio of recycled coarse aggregate』 was set to total 12 combinations by applying 0, 30, 50, 100[%] replacement ratio of recycled coarse aggregate to 21, 27, 35[MPa] to the design standard strength. During the experiment of fracture strength, strength degradation due to the replacement rate of recycled coarse aggregate did not occur, and it was found that the wave velocity also increased along with an increase in strength due to the age of recycled coarse aggregate concrete.

Abstract: In this paper we report the composition, mechanical and fracture properties of eight types of performance-designed high strength concrete. The influences of compositions on the material’s brittleness are explained through the calculated reference size of the Fracture Process Zone (FPZ).

Abstract: Based on wind velocity spectrum generated by CAWS method, the dynamic response of tower is computed by Ansys software. The wind-reduced displacement response, force response and acceleration response are acquired. At the same time, wind load factor based on displacement equivalence and force equivalence is acquired.

Abstract: Large-scale projects have the features that large organization size, complex relationships between the organization and a serious information asymmetry between project participants. This study carries out in-depth economic analysis about large-scale projects organization, based on principal-agent theory and transaction cost theory from the perspective of new institutional economics, at the same time, establish the economic theoretical framework, it has positive significance to the rational design of the project contract and scientific analysis of the construction economic relations.

Abstract: This paper presents a low-power multistage amplifier with a novel Transconductance with Capacitances Feedback Compensation (TCFC) technique. A transconductance stage and two capacitors introduce negative feedback to a three-stage amplifier, which significantly improves the performance such as gain-bandwidth product, slew rate, stability and sensitivity. Implemented in a commercial 0.5-μm CMOS technology and driving 10pF capacitive load, a three-stage TCFC amplifier achieves over 120dB gain, 1.515MHz GBW and 1.3V/μS average slew rate, while only dissipating 380μW under 3.3V supply.