固定海上平台遭受水下爆炸载荷的非线性动态响应

In this paper,the dynamic response of a fixed offshore platform subjected to the underwater explosion(UNDEX)and probable events following it have been investigated.The pressure load due to UNDEX in a specified depth has been applied with a model that considers the effect of blast bubble fluctuations into account.The effect of water on the natural frequency and Fluid-Structure interaction has been modeled as equivalent added mass formulation.The effect of explosion distance on platform response is studied.In this regard,three cases of near,medium,and far-distance explosions are considered.For a case study,a real fixed offshore jacket platform,installed in the Persian Gulf,has been examined.Only the UNDEX pressure load is considered and other dynamic loads such as surface water waves and winds have been neglected.Dead loads,live loads and hydrostatic pressure has been considered in the static case based on the design codes.The results indicated that in near-distance explosions,the UNDEX pressure load can locally damage parts of the platform that are located at the same level as that of explosive material and it can destabilize the platform.In the medium to far distance explosion,a very large base shear was applied to the platform because more elements were exposed to the UNDEX load compared to the near-distance explosion.Therefore,precautionary measures against UNDEX such as risk assessment according to design codes are necessary.As a result of this,member strengthening against explosion may be required.

New Design for Creating Safe Places to Reduce Earthquake Loss and the Best Way to Rescue and Relief People

Immunization and upgrading of structures are for the prevention of physical and financial losses due to earthquake. The importance of structures is not the same regarding the physical and financial losses caused by the earthquake damage, although the responsibility to improve and secure them in terms of providing financing according to the type of ownership is different. The formulation of rules, regulations and necessary letters, the supervision over the various stages of immunization, and the establishment of appropriate facilities are in accordance with the financial and executive capacity of the country, the prioritization and preparation of a major plan for the improvement and securing of government responsibilities. Old buildings in worn-out textures generally have a wall system without vertical and horizontal shafts. The experiences from Boijin Zahra, Tabas, Rudbar and Bam earthquakes indicate that the destruction of such buildings in the time of devastating shakes is definite. The importance of structures is not the same considering the physical and financial losses caused by the earthquake damage. The principal destruction and rehabilitation for prevention of physical and financial losses due to the earthquake in terms of providing financing and according to the type of ownership varies, and this requires a rebuild time and high costs for the employer. Therefore, it is recommended that according to the conditions of the buildings of the country, arrangements and decisions, whether for financial facilities, etc. are considered so that everyone can carry out the executive steps of the safe room according to their existing structures.

Analysis of jacking forces during pipe jacking in granular materials using particle methods

Trenchless technology is often used in congested urban areas or river crossings to install underground pipelines to minimize disturbance to surface traffic or other activities.Pipe jacking is a typical technique applied to jack pipe segments between two working shafts.However,the design of the jacking force is usually implemented using empirical methods.It should be emphasized that the jacking force will change for each site,depending on the magnitude of overcut,lubricants,work stoppages,geology and misalignment.A particle method is proposed to estimate the jacking force along the pipe.The microparameters are calibrated for sandy soils in Shenyang,so that the macroscale material behavior can be reproduced using the particle model.Hence,the normal force around the pipe circumference can be derived in the particle model,after which the interface friction coefficient is applied to evaluate the friction resistance mobilized at the soil-pipe interface.A modified Protodyakonov’s arch model can be used to assess the magnitude of earth pressure acting on the shield face.In the end,the combination of friction resistance and face pressure provides the jacking force.The efficacy of the proposed particle method is demonstrated by comparing calculated jacking forces with those measured in the field for three types of jacking machines in sandy soils under the Hun River,Shenyang.

D-Dimensional Dirac Equation for Energy-Dependent Pseudoharmonic and Mie-type Potentials via SUSYQM

We investigate the approximate solution of the Dirac equation for energy-dependent pseudoharmonic and Mie-type potentials under the pseudospin and spin symmetries using the supersymmetry quantum mechanics. We obtain the bound-state energy equation in an analytical manner and comment on the system behavior via various figures and tables.

Pseudospin symmetry of the Dirac equation for a MSbius square plus Mie type potential with a Coulomb-like tensor interaction via SUSYQM

We investigate the approximate solution of the Dirac equation for a combination of Mobius square and Mie type potentials under the pseudospin symmetry limit by using supersymmetry quantum mechanics. We obtain the bound-state energy equation and the corresponding spinor wave functions in an approximate analytical manner. We comment on the system via various useful figures and tables.

Enhancing compressive strength and durability of self-compacting concrete modified with controlled-burnt sugarcane bagasse ash-blended cements

In sugar industries,the growing amount of sugarcane bagasse ash(SBA),a byproduct released after burning bagasse for producing electricity,is currently causing environmental pollution.The residual ash displays a pozzolanic potential;and hence,it has potential as a cement addictive.This study focuses on enhancing suitability of SBA through incorporating ground blast furnace slag(BFS)in manufacturing self-compacting concretes(SCCs).For this purpose,SBA was processed by burning at 700°C for 1 h,before being ground to the cement fineness of 4010 cm2/g.SCC mixtures were prepared by changing the proportions of SBA and BFS(i.e.,10%,20%,and 30%)in blended systems;and their performance was investigated.Test results showed that the presence of amorphous silica was detected for the processed SBA,revealing that the strength activity index was above 80%.The compressive strength of SCC containing SBA(without BFS)could reach 98%–127%of that of the control;combination of SBA and 30%BFS gets a similar strength to the control after 28 d.Regarding durability,the 10%SBA+30%BFS mix exhibited the lowest risk of corrosion.Moreover,the joint use of SBA and BFS enhanced significantly the SCC’s sulfate resistance.Finally,a hyperbolic formula for interpolating the compressive strength of the SBA-based SCC was proposed and validated with error range estimated within±10%.

Assessment of novel nature-inspired fuzzy models for predicting long contraction scouring and related uncertainties

The scouring phenomenon is one of the major problems experienced in hydraulic engineering.In this study,an adaptive neuro-fuzzy inference system is hybridized with several evolutionary approaches,including the ant colony optimization,genetic algorithm,teaching-learning-based optimization,biogeographical-based optimization,and invasive weed optimization for estimating the long contraction scour depth.The proposed hybrid models are built using non-dimensional information collected from previous studies.The proposed hybrid intelligent models are evaluated using several statistical performance metrics and graphical presentations.Besides,the uncertainty of models,variables,and data are inspected.Based on the achieved modeling results,adaptive neuro-fuzzy inference system-biogeographic based optimization(ANFIS-BBO)provides superior prediction accuracy compared to others,with a maximum correlation coefficient(R_(test)=0.923)and minimum root mean square error value(RMSE_(test)=0.0193).Thus,the proposed ANFIS-BBO is a capable cost-effective method for predicting long contraction scouring,thus,contributing to the base knowledge of hydraulic structure sustainability.