Mega-columns with a solid section area of nearly 20m2 are used in super
high-rise buildings. However, their fundamental mechanical behaviors
are very difficult to be studied with current experiment equipments
and technology. In order to solve this problem, this paper discusses
the elasto-plastic behavior of the mega-columns and establishes the
corresponding simplified models. Firstly, detailed finite element models
of the mega-columns are built up with solid elements based on the general-purpose
finite element program-MSC.MARC. Typical load cases are applied on the
detailed FE model. And then the influences of two widely used yield
criteria (von Mises criterion and Drucker-Prager criterion) of concrete
are discussed. The comparisons indicate that the mechanical characters
of the mega-columns are not sensitive to the yield criteria, and the
confinement will have some influence on the deformation capacity. However
such differences can be ignored in practical use. The methodology to
build up the simplified models of the mega-columns is presented and
the results of the simplified model agree well with the results of the
detailed FE model. The workload of the simplified model is much smaller
than the detailed FE model. So it can be used in global structural elasto-plastic
analysis and collapse simulation.
is a key index to assess whether a structure can be reused or restored
after an earthquake. In this paper, a PC frame has been simulated with
various bonding styles of PS by a fiber model program developed and
validated with test data in this study, and some simple discussions
on the effect on re-centering behavior of the bonding styles of PS have
been given. The results of simulation indicate that, as to PC frames
designed according to codes in existence, the bonding style of PS used
for columns has great influence on the re-centering behavior of PC frame,
while the PS of beams have relatively little effect. According to the
numerical results and considering the entire performance of PC frames,
it should take priority to use the partially debonding style of PS in
the engineering practice.
Abstract:The concept of robustness
of structures is firstly introduced in this paper. And importance with
enough robustness for seismic structures in preventing collapse of the
structures under strong intensity earthquake attack is discussed. Then
the approaches to increase the robustness of seismic structures, including
structural systems, strength and ductility of structure, failure modes
and redundancy, are suggested.
ABSTRACT: A novel distributed tuned liquid damper (DTLD) to reduce the vibration of structures is pro-posed in this paper. Its basic working principle is filling of the empty space inside the pipes or boxes of the cast-in-situ hollow reinforced concrete (RC) floor slabs with water or other damping liquid. Hence these pipes or boxes will work as a series of small TLDs inside the structure. Thus, no additional spaces are needed for TLDs whilst the damping ratio of the whole structure is obviously increased. Numerical simulation with the fluid-structure coupled effect is carried out to evaluate its vibration-reduction effect. The results indicate that distributed TLD can considerably increase the damping of the building and thus reduce the vibration. Some parameters influencing the vibration-reduction are also studied.
Keywords: distributed tuned liquid damper (DTLD), fluid-structure interaction (FSI), vibration reduction, hol-low floor slab
Abstract: Currently cast-in-situ hollow reinforced concrete (RC) floor has been used widely in construction. If the empty space inside the pipes and the boxes embedded in the hollow floor is filled with some cheap liquid (such as water) to build up distributed TLD (tuned liquid dampers), then the total damping of the structure will be increased which results in a reduction of vibration. And this distributed TLD has some more advantages beside vibration control such as low cost and never occupying usable space. So it is believed that distributed TLD inside hollow floor will has a bright future. This paper demonstrates the feasibility of distributed TLD with the fluid-structure coupled simulation ability of common finite element package ANSYS. Parametric discussions are presented to show the factors that may govern the effect of vibration reduction. And the numerical results proved that distributed TLD has obvious effects to reduce the seismic vibration.
Keywords: distributed TLD, fluid-solid
coupled simulation, vibration reduction, hollow floor
strength/performance structural materials and the developments of modern
engineering structures and the design theory
Abstract: This paper firstly presents the latest development of high strength/performance structural materials in recent years. The rational applications and examples of high strength/ performance structural materials in the structural systems to obtain high performance are discussed and presented. The positive functions of high strength reinforcement used in reinforced concrete frame structures, that can enhance the structural performance against earthquake and reduce the structural seismic damage, are investigated in detail with nonlinear pushover analysis and dynamic analysis. The results show that the high seismic performance of the reinforced concrete frames, including a delayed appearance of plastic hinges at the bottom story columns feet, to form a rational failure mechanism under strong earthquake, and a small residual displacement after earthquake that cause an easy retrofitting after earthquake, can be obtained by replacing normal strength reinforcement with high strength reinforcement in the columns. Finally, the development of the safety and design theory for the structures using high strength/performance materials are discussed.
Keywords: High strength/performance concrete; High strength/performance steel; Engineering Structures; Structure safety; Design theory; Accidental event; Earthquake resistance.