Today, we are traveling south from Tiachung, basically following route 3. This route follows along the base of the mountain range that borders the eastern edge of the valley in which Tiachung is located. One of the major north-south fault ruptures east of Tiachung surfaces along the base of these mountains. Again, observations are reported chronologically, according to the GPS station identification tags assigned to the site visited. Our first stop is at the Ijiang Bridge at the intersection of Highways 129 and 136. This is an old bridge with relatively short, simply supported, reinforced concrete spans. Two unsymmetrical precast units make up the bridge deck. The spans are apparently supported directly on the concrete bent cap, without either bearings, restrainers or keys. It appears from construction on the site that a replacement bridge was already under construction along the same alignment at the time of the earthquake. Parts of the piers for the new bridge may be seen on either side of the existing bridge   Water flow in the river has come nearly to a complete stop, reportedly due to a large landslide blocking the river upstream. Traffic was currently diverted on to a surface road constructed directly on the river bed. A small temporary metal bridge was under construction upstream of the damaged bridge to accommodate the eventual water flow in the river channel once the landslide is cleared away.   Damage to the bridge again seems due in large part to ground rupturing directly beneath the bridge. In this case, several ruptures appear to break surface near the northern end of the bridge (these ruptures run nearly perpendicular to the bridge, and tend to shorten, rather than skew the bridge). The southern end of the bridge appears to have been shoved northward, dislodging several of the northernmost spans from their supporting piers.   The abutment at the southern end of the bridges shows significant compression damage and permanent displacement. Near one of the apparent ruptures near the northern end of the bridge, one of the piers has tilted. The piers to the right and left of the tilted pier in the photo remain relatively plumb. The spacing between the three piers, however, is no longer equal, consistent with ground movement in this area. As a result, the southern ends of the spans at the northern end of the bridge have been pushed far off of their supporting piers (actually, it is possible that the spans have remained in place and the ground and supporting piers have moved; a combination of actions is likely). The bridge deck spans ended up tilted in various (often at steep angles), since they still generally rested on one pier At the northernmost end of the bridge, the rupture in this area has apparently raised the ground and piers relative to the end abutment, resulting in a large variation in pier heights. The bridge deck at the north end of the bridge has ended up more than 9 meters beyond the end of the abutment The rupture near the end of the bridge continues eastward into and across the river bed and westward into a group of structures. The rupture has also lifted the ground about 3 meters in this area, resulting in damage to nearby structures. Note that the raised portion of earth on the left side of the photo was reportedly at the same elevation as the land on the right side prior to the earthquake. In spite of being tilted at a severe angle, a three story reinforced concrete building is without any structural damage. A portion of a two story reinforced concrete building, situated on the foot wall side of the rupture, has been demolished and is currently being rebuilt. It was damaged due to the earth bank raised by the hanging wall portion of the rupture pushing up against the edge of this large building. Continuing further south, we follow the foothills through small towns that have minor to moderate damage. Entering the outskirts of Dali, we come to a new appearing elementary school. The Jianmin Elementary School appears to be a modern, three story reinforced concrete structures. The school seems to have very little structural damage. However, most of its partitions are made from unreinforced brick. In a few locations these walls suffered moderate to severe damage. The building has also pounded up against a neighboring structure, having similar features, but oriented perpendicular to the damaged building. These other buildings show little evidence of damage and are currently being used for instruction. This difference in damage may suggest a directivity effect in the area. One of the adjacent school buildings show evidence of moderate pounding damage (a separation of less than 10 cm was provided) where it impacted with the first building. The building is being demolished, in spite of the modest amount of nonstructural damage. Entering the main part of Dali, damage appears to be moderate to minor. We observe brick and other debris removed from the interior of many older buildings, suggesting damage to interior partitions. Occasionally, we see the remnants of low rise buildings that have already been demolished or are in the process of demolition. In the heart of the old section of Dali, we note a seven story commercial building that suffered a collapse of the third story. On the southern side of Dali, we note many newer highrise apartment complexes. Some of these have suffered local collapses of one story and have tilted or are shorter than other buildings in the same complex. Most buildings appear to have sustained the earthquake without any damage. Rather than look at these buildings, we decide to continue southward today and visit these and other buildings located closer to Tiachung on Sunday. On the southern side of Dali, we stop at a 10 story reinforced concrete building. Construction appears to have been interrupted quite some time prior to the earthquake. There are several similar buildings in the general vicinity (also with construction interrupted). This building suffered minor structural damage to its moment frame, especially near the base of the ground story columns. Column splices were at the floor level and ties had 90 degree hooks. Cross ties were provided; these had 180 degree hooks. Some joint distress was noted. Generally, joint transverse reinforcement was very light. This building also suffered moderate to major damage to its reinforced concrete architectural partitions. Throughout the Tiachung area it is apparent that most partitions and exterior cladding are constructed from reinforced concrete or brick. It is apparent in most instances that these elements are not considered structural. Reinforced concrete walls consist of thin 10-12 cm wide, reinforced concrete panels (with a single light curtain of reinforcement) cast monolithically with the frame. Single and double wythe brick wall panels are also used. In the building visited, the cladding and interior walls were largely constructed from reinforced concrete. These suffered extensive damage in the lower floor levels. From Dali to Wu Fang a number of reasonably new mid- to high-rise reinforced concrete buildings were noted. While most of these appear to have performed well, an increasing number of them appear to be damaged in comparison to most other areas visited today. Some damaged buildings are tilted and one in downtown Wu Fang has collapsed into the street. Most of the heavily damaged buildings are being demolished rapidly. An elementary school in Wu Fang was inspected. This school complex was made up of a number of 2 and 3 story reinforced concrete buildings. It appears that the various units were constructed at different times. The oldest-looking unit on the site did not suffer any structural or nonstructural damage. The newer-looking buildings suffered a wide range of damage ranging from none to complete collapse. The building in the rear of the photo was essentially undamaged and appeared to be the newest structure in the complex. One unit completely collapsed. The three story building on the right side of the photo lost its ground story. Two other units suffered intermediate amounts of damage. The buildings that suffered complete or partial collapse appear to be constructed consistent with pre-1970s US construction practices. Column splices are at the base of the columns. Column ties are spaced at the minimum dimension of the column. No transverse reinforcement is provided in the joints. Failures are noted in the partially collapsed portions of the building due to insufficient confinement in the columns Captive columns and large diameter drain pipes and aggregate were noted in some columns. The two building units that suffered partial collapse had similar details, but the units were oriented 90 degrees relative to the ones that collapsed completely, and had a number of different architectural details (since they bordered on the front of the school). In some of the buildings around the Wu Fang Elementary School, it was noted that the ground slabs had been removed from apparently otherwise only modestly damaged buildings and new slabs on grade were being constructed. In the Wu Fang school, the slabs on grade were seen to have swelled up possibly as a result of building settlement. No evidence of liquefaction was seen. The soil was cobbly throughout the area. While differential settlement may have been a problem at the building, it was not likely the main reason for the poor behavior of these structures. The next stop was another elementary school a few miles further south, at the mouth of a small valley extending up into the mountains. The Kuang Fu Elementary School was traversed by large rupture, that upheaved the ground in some locations by about 3 meters. In other locations, the rupture appears to have separated into 2 or more smaller branches. The school complex consisted of a number of buildings including 2 and three story classroom wings, a large auditorium (apparently undamaged), sports complex (undamaged) and so on. Much of the worst damage on the site is due to relative ground displacements under the buildings resulting from the ground rupture. A relatively new classroom structure, running roughly perpendicular to the rupture trace, suffered only minor damage. These classroom structures were relatively narrow (one room wide) and long (several classrooms, separated by brick partitions). Damage in this newer appearing building consisted of cracking at the ends of some of the reinforced concrete beams and columns as well as working of the brick infilled walls. The most highly damaged infills have already been repaired and the building was back in use. Temporary class rooms were constructed in tents and in the sports complex . An older-looking, three-story reinforced concrete classroom unit running parallel to the one described in the previous paragraph was heavily damaged as a result of ground shaking. Damage to the ground story columns was severe; orientation of the damage was consistent with longitudinal movement of the building. Column details were similar to those described earlier; large spacing between ties, 90 degree hooks, no special confining reinforcement, splices at floor level, and captive column effects. Columns shortened by partial height infill partitions, accentuated column damage in the longitudinal direction compared with damage to unshortened columns Cracking in many of the transverse running brick walls was also severe. Several buildings were located astride the rupture. One of these buildings was parallel to, and configured similarly to, the one described in the previous paragraph. Most of this building collapsed. One of the rupture traces going through the building can be seen in the photo. One portion of the building immediately adjacent to the rupture, on the foot wall side, remained standing. However, like the portion of the Ijiang Bridge that straddled a rupture, the spacing between the supporting columns was reduced in this section. The next section along the building (and a three story tall covered walkway next to it) collapsed (weak first story mechanism). Other buildings astride the rupture were severely damaged, but did not collapse at this site. Many buildings in the Tiachung area have water storage tanks on their roofs. In most cases, these are not damaged, but a variety of damage was observed. At the Kuang Fu School, one of these tanks buckled and the supporting structure was damaged.   The next stop was a pair of parallel reinforced concrete bridges on Route 3 crossing the Wu River.   These bridges were severely damaged at the north end where a rupture trace passed under the bridges at a skew.   As a result of the skew, the bridges tended to shorten, resulting in the southern spans pushing the northern spans off their seats, and moderate compression damage and permanent displacement to the abutments was noted. Two spans at the north end of the north bound traffic bridge collapsed. Because of the skew of the rupture under the bridge, it appears that the eastern bridge also moved west relative to the western one (where the piers for the two bridges at the same distance along the bridge sit on different sides of the rupture). It appears that the contact (and shaking) resulted in a severe inclined crack consistent with motion to the west. The older and considerably larger piers supporting the eastern bridge did not crack, except in the area where the rupture appears to have passed directly under the edge of the damaged pier. All of these piers have very light longitudinal reinforcement (less than 1%) and small amounts of transverse reinforcement, consistent with the formation of a single concentrated crack. A new bridge down stream from the damaged bridges described above on Route 63 appear to be in good shape. These are considerably newer and were not traversed by the rupture. A typical elevated viaduct on Route 63 is shown. No damage or working of the pier shaft in the ground was noted. An electrical power transmission tower about a kilometer upstream from the damaged bridge was seen to be tilted noticeably. The tower was a steel truss supported on a reinforced concrete frame. The legs of the concrete frame appear to have suffered differential settlement. It was not possible to get access to the tower to do a more detailed inspection.   The team attempted to inspect damages in Nantou prior to sunset. However, traffic in the older part of town prevented this prior to nightfall. The team returned to Tiachung. Steve Mahin