Home / Information / Laboratories and Academic Staff / Built Environment Materials and Structural Systems

Built Environment Materials and Structural Systems

Our laboratory is engaged in researches of steel and reinforced concrete structures. Through investigating advantages and disadvantages of steel and concrete, we make proposals to improve structural safety and to reduce environmental load.

The researches comprise of experimental test with scaled models of building columns, beams and walls, and numerical simulation including finite element analysis.

Academic Staff

Yoshio KANEKO

Yoshio KANEKOProfessor (Graduate School of Engineering)

Research Topics

  1. Development of constitutive laws of cementitious composites and high-performance alloys
  2. Development of new joint systems in structures
  3. Smart structures based on damage-controlled mechanism
  4. Development and design application of mechanical models based on constitutive laws

Contacts

Room 485, Bldg. C1, Katsura Campus
TEL: +81-75-383-3285
FAX: +81-75-383-3285
E-mail: kaneko@archi.kyoto-u.ac.jp

Yuichi SATO

Yuichi SATOAssistant Professor (Graduate School of Engineering)

Research Topics

  1. Study on characteristics of crack and bond of cementitious composites
  2. Finite element analyses of building structures and materials

Contacts

Room 488, Bldg. C1, Katsura Campus
TEL: +81-75-383-3288
FAX: +81-75-383-3288
E-mail: satou@archi.kyoto-u.ac.jp

Research Topics

 Development of the damage control design procedure for reinforced concrete building structures

(a) Cementitious Damping Wall

An energy absorption wall with multi-stage destructive mechanism is experimentally investigated. The wall is made by filling gaps between alignments of energy absorption members. The energy absorption members are made by hybrid fiber reinforced cementitious composites and steel bars. Shear test specimens were prepared with two kinds of energy absorption members and subjected to reversed cyclic loading. The test results show that the energy absorption walls clearly give the multi-stage destructive mechanism as well as ductile hysteresis response.

(b) TRIP Alloy

Damage-detection characteristics of Fe–Cr stainless alloy, TRIP (transformation induced plasticity) steels are investigated. Capability of TRIP steels in assessments of structural performance degradation is evaluated through material tests. Magnetic characteristics of TRIP steels under tensile and compressive uniaxial loadings are investigated through the measurement of induced voltage. The stress–strain hysteresis and the associated magnetic alternation of TRIP steels are identified. In addition, plate-bending tests and beam-bending tests are carried out in order to study the damage-detection characteristics. Dual function of TRIP steels, serving as both a high ductility load-carrying member and a sensor to monitor damage accumulation, is finally confirmed.

Fig.1
Figure 1. Umbrella city as disaster prevention system

Retrofit/Rehabilitation of the existing building structures vulnerable to earthquake damage

Steel fibers mixed in fiber reinforced cementitious composites are processed in various shapes with various coatings to improve mixing and bond in mortar. However, these processes increase the costs of the fibers. If sawdust, or steel chips, wasted from lathes in metalwork factories can be used as an alternative of the steel fibers, then they will contribute to reduce the amount of the wastes, the costs, and save the steel resources.

Up to now, the steel chips are regarded as a kind of industrial wastes and subjected to the landfill disposal instead of the reuse. We attempts to use steel chips of “precisely-processed steel plates (PPSL),” whose quantity of production is remarkably increasing. Our tests show that the steel chips of PPSL successfully enhance the strengths and ductility of the cementitious materials without deteriorating the workability.

It is thought that one of the most effective applications of the Steel Chip Reinforced Cementitious Composite (SCRCC) to structural members is base-column joints of steel structures. The structural test shows that the strengthening with the SCRCC is not superior to the SFRCC, but considerably enhance the load comparing to the strengthening with the normal concrete. The ductility is also enhanced so that shear fracture of strengthening parts are prevented.

fig2a.pngfig2b.png
Figure 2. Structural test of base-column joint using SCRCC

Numerical prediction of behaviors of building structures under various loading conditions

In structural analyses of RC using the FE method, all-frame analyses are more often conducted whereas previously, partial analyses of a column, beam, wall, and beam-column joint, etc. were mostly conducted.

For example, nonlinear analyses were conducted of RC structural members with 3D lattice models. The models consisted of diagonal and arch elements in addition to vertical and horizontal elements. The models enable reasonable predictions of seismic behavior of RC columns subject to torsional and biaxial motions.

Other researchers evaluated the potential progressive collapse of an actual 10-story RC structure using experimental and dynamic nonlinear analyses. These analytical results clearly simulated the actual behavior of the structure although the analytical models were composed of simple fiber elements.

More sophisticated analyses were conducted shaking table tests of a one third scale RC multi-story frame model and three dimensional dynamic nonlinear analyses using a FE model composed of eight-node-hexahedral elements. The analytical results clearly simulated the dynamic response and structural damage.

All-frame nonlinear FE analyses possess significant advantages in that (i) the nonlinear behavior of walls can be directly computed and (ii) nonlinear interactions between walls and columns are taken into account. For example, the analysis can consider shear failure of a column shortened by a low-rise spandrel wall. On the other hand, all-frame analyses tend to adopt a coarse mesh discretization due to limited computer resources. The concrete material model used in the FE analyses is usually derived from specimens of 50 mm to 200 mm in size while the element size in a model with coarse mesh discretization is hundreds to thousands of millimeters. The validity of conventional material models to large-size elements is therefore questionable.

Our research tries to enhance analytical accuracy through re-modeling the constitutive material laws to enable the dynamic 3D analysis of full-structure FE models.

fig3.png
Figure 3. FE seismic response analysis of reinforced concrete building