The dynamic response of a prestressed concrete box girder bridge under the impact an over-height vehicle is studied using numerical simulation method. finite element analysis software LS-DYNA used to simulate collision between superstructure and truck. Further, parametric carried out investigate influence six factors, i.e., configuration, speed, mass, angle, strength strand prestress, on both l...

The mechanism uncoupling isoprene emission and photosynthesis under drought was investigated in Populus alba saplings. Isoprene emission, incorporation of 13C into the isoprene molecule, isoprene synthase (ISPS) activity, concentration and gene expression, and photosynthesis were measured as a function of the fraction of transpirable soil water (FTSW) and in plants recovering from drought. Phot...

This paper defines two concepts of rigidity for tensegrity frameworks (frameworks with cables, bars, and struts): prestress stability and second-order rigidity. We demonstrate a hierarchy of rigidity--first-order rigidity implies prestress stability implies second-order rigidity implies rigiditymfor any framework. Examples show that none of these implications are reversible, even for bar framew...

Plectin is a 500-kDa cross-linking protein that plays important roles in a number of cell functions including migration and wound healing. We set out to characterize the role of plectin in mechanical properties of living cells. Plectin(-/-) cells were less stiff than plectin(+/+) cells, but the slopes of the two power laws in response to loading frequencies (0.002-1,000 Hz) were similar. Plecti...

The recovery stress of martensitic shape-memory alloy [SMA] wires can be used to confine concrete, and the confining effectiveness of the SMA wires was previously proved through experimental tests. However, the behavior of SMA wires under recovery stress has not been seriously investigated. Thus, this study conducted a series of tests of NiTiNb martensitic SMA wires under recovery stress with v...

In this paper, we define a general class of tensegrity structures consisting of both compression members (ie bars) and tensile members (ie cables). For a given number N of bars, we define the topological structure which is necessary to establish a tensegrity. Necessary and sufficient conditions for prestress mechanical equilibria of the tensegrity are then provided in terms of a nonlinear funct...