In recent earthquakes in developing countries, severe damage was observed on reinforced concrete buildings. This study focuses on exterior beamcolumn joints with substandard beam rebar anchorage and seismic strengthening by installing wing walls. First, a series of experiments was conducted to investigate the seismic behavior of exterior joints with substandard beam rebar anchorage representing typical Bangladeshi buildings.Two 0.7-scaled exterior joint specimens were tested, and these specimens showed beam rebar anchorage failure and/or joint shear failure. Prior to strengthening of the joint, a series of pullout tests was conducted on postinstalled bonded anchors in low-strength concrete for strengthening design.Then, an experiment was performed to apply the strengthening method by wing walls to one of the exterior joint specimens to improve the integrity, and this method was intended to prevent the failure of beam rebar anchorage. The strengthening method is proposed to extend the development length of beam longitudinal bars by considering the embedment length along the wing walls. The test results verified the effectiveness and applicability of the proposed strengthening method to upgrade exterior RC beamcolumn joints with deficient beam rebar anchorage. K E Y W O R D Sanchorage failure, developing country, low-strength concrete, reinforced concrete, seismic strengthening, substandard structure

Significant damage to reinforced concrete buildings by the 2009 Western Sumatera Earthquake revealed that deficiencies in design engineering and/or construction practice existed. This indicated that enforcement of building design codes was lacking. The Indonesian government has updated the building design codes which should have been applied in the construction of new buildings. However, enforcement of these codes on design engineering and/or construction practice in Padang city is not clear. In this study, a field investigation was performed to investigate common structural details and deficiencies in newly constructed multi-story reinforced concrete buildings. The investigation was conducted through visiting building construction sites in Padang city area. This study preliminary reports the investigation results on 39 private buildings and 8 government buildings. The common deficiencies found on the investigated buildings were low material quality, small structural dimensions with light longitudinal reinforcement, insufficient transverse reinforcement with poor details, improper location of lap splice of rebar, lack of hoops inside exterior and interior beam-column joints, and deficient anchorage of beam reinforcement to exterior beam-column joints. These investigation results clarify that enforcement of the latest buildings design codes in design engineering and/or construction practice is still lacking in the investigated area.

In Kerinci Regency, especially around areas of Gunung Tujuh and Siulak areas, people generally use materials from Sungai Rumpun quarry and Siulak Deras quarry for the concrete mixture. A preliminary test by organic impurity test showed that the organic substances in the aggregate from the Sungai Rumpun quarry had a high organic content, while the aggregate from the Siulak Deras quarry had a low organic content. Therefore, this study aims to investigate the characteristics of the aggregate from Sungai Rumpun quarry and the Siulak Deras quarry and to determine the effect of the use of coarse and fine aggregate from both quarries on the compressive strength of concrete. This study is an experimental research that is conducted at the Civil Engineering Laboratory of the Padang Institute of Technology (ITP). In this study, the tests for physical properties of coarse and fine aggregates are conducted, then samples for the concrete compressive test are prepared, and the compressive strength test is carried out. Based on the results of this study, it can be concluded that aggregates from the Sungai Rumpun quarry are not recommended to be used for the concrete mixture of normal strength concrete (fc'=20 MPa), because the results of the compressive strength test showed that the average compressive strength does not reach the designed compressive strength (fc'). On the other hand, the aggregates from the Siulak Deras are recommended to be used for the concrete mixture of normal strength concrete because the compressive strength reaches the designed compressive strength.

This paper discusses a feasible application of wide hoop spacing to reinforced concrete (RC) columns using mechanical splices for longitudinal bars to simplify and accelerate practical construction. Twenty-two RC columns with/without wide hoop spacing at mechanical splices were experimentally investigated in terms of the shear performance. First, a series of experiments on the application of the proposed hoop arrangement to shear-critical columns was conducted.The tests indicated that the negative effects of the proposed hoop arrangement on the column shear performance were limited and that the wide hoop spacing reduced the shear strengths by up to 12%. Therefore, two structural indices for evaluating the shear strength of columns with the proposed hoop arrangement were presented and verified based on the experimental results. Consequently, strong agreement was obtained between the experimental shear strengths and the estimations obtained with the proposed shear strength evaluation method. Then, a second series of experiments was performed to apply the proposed evaluation method to practical shear design for ductile columns. Premature shear failure in the ductile columns was successfully prevented, thus verifying the effectiveness of the shear design. Furthermore, the rotation angles at shear failure after flexural yielding could be appropriately estimated for several columns by combining the proposed evaluation method with idealized bending performance.