平成２６年 ６月 ２６日
Mechanical and Structural System Engineering

ID

119105AdvisorName

Title

Yulia Hayati

Tomoya Matsui
Taiki Saito

Development of Out-of-plane Strengthening System by Passive Compression for
Masonry Walls（800 words）

Masonry is one of the oldest structural systems and has been widely used over the world
even after engineering materials such as concrete and steel had been introduced in construction.
Brick masonry is still the most popular building component in developing countries due to its
easy handling and cost-effectiveness. Masonry walls typically have low flexural capacities andpossess brittle failure modes when exposed to out-of-plane loads.
The current study focuses on improving the out-of-plane performance of masonry walls.
Field investigation was conducted on damaged buildings in a central region of Aceh province by
the 2013 Aceh, Indonesia earthquake. Building structural systems in the area are roughlyclassified into four types: 1) reinforced concrete, 2) confined masonry, 3) timber, and 4) timberwith masonry spandrel walls. Reinforced concrete and confined masonry suffered from moderate
to heavy damage. On the contrary, damage to timber was none to light. The major cause ofdamage to confined masonry structures was out-of-plane failure of masonry walls. One of thecollapsed buildings was focused to evaluate the minimum seismic resistance of masonry walls in
the out-of-plane direction. As a result, it was found that the masonry wall collapsed because it
could not withstand the intensity of the earthquake that occurred in the area. It shows a need toupgrade the out-of-plane performance of masonry walls to prevent such kind of collapse.
The new out-of-plane loading system for masonry walls is proposed in this study.
Uniformly distributed loads are applied to masonry walls by using a rubber airbag. The test
system was developed aiming at obtaining basic mechanical characteristics of simply supported
masonry walls in the out-of-plane direction. A test with an aluminum plate specimen wasconducted to verify the developed loading system. An easy to handle and lightweight specimen
with dimensions of 190 mm x 10 mm for a cross section and a length of 900 mm was used.
Consequently, the test results clarified good agreements between the experimental measurements
and theoretical estimations.

This study proposes a new out-of-plane strengthening method for masonry walls withpassive compression, which is applied to wall cross-section by restraining axial deformation withsteel rods. The new strengthening system utilizes geometric deformation characteristics ofmasonry as well as the mechanism of conventional post-tensioning system. Outer steel rods areprovided to apply compression to wall cross-section. Compression is passively induced withgeometric axial elongation under out-of-plane loads which is caused by structural characteristicsof masonry itself. The strengthening mechanism is implemented to verify its availability. Threebrick wall specimens were prepared and tested with/without strengthening with dimensions of190 mm x 140 mm x 900 mm in width x thickness x length (height). The M8 steel rods whichwere placed along the wall length and fixed to steel end plates provided on the wall ends are used
for strengthening material. As a result, the proposed method significantly improved the structural
performance of walls in the out-of-plane direction.
Moreover, a theoretical calculation procedure is presented for the performance evaluation.
Verification of the proposed analytical method was conducted through simulating theexperimental results of strengthened masonry walls. As a result, good agreements were observed
between the experimental and analytical results on the performance evaluation of masonry. Thus,
the proposed analytical method can be applied reasonably for estimating the out-of-plane
performance of masonry walls strengthened by the proposed method. Moreover, the performanceof typical masonry wall in Aceh was evaluated by applying the proposed analytical method.
Finally, it was found that the proposed system can effectively improve the out-of-plane
performance of masonry walls.